Description
WELLPLAN, Release 2000.0 Training Manual copyright © 2001 by Landmark Graphics Corporation Part No. 157853 March 2001 Copyright © 2001 Landmark Graphics Corporation All Rights Reserved Worldwide This publication has been provided pursuant to an agreement containing restrictions on its use. The publication is also protected by Federal copyright law. No part of this publication may be copied or distributed, transmitted, transcribed, stored in a retrieval system, or translated into any human or computer language, in any form or by any means, electronic, magnetic, manual, or otherwise, or disclosed to third parties without the express written permission of: Landmark Graphics Corporation 15150 Memorial Drive, Houston, TX 77079, U.S.A. Phone: 281-560-1000 FAX: 281-560-1401 Internet: www.lgc.com Trademark Notice Landmark, 3DVIEW, ARIES, Automate, BLITZ, BLITZPAK, CasingSeat, COMPASS, Contouring Assistant, DecisionSpace, Decision Suite, Decisionarium, DepthTeam, DepthTeam Explorer, DepthTeam Express, DepthTeam Extreme, DepthTeam Interpreter, DESKTOP-PVT, DESKTOP-VIP, DEX, DFW, DIMS, Drillability Suite, DrillModel, DSS, EarthCube, EdgeCa$h, Fast Track, FZAP!, GeoDataLoad, GeoLink, GRIDGENR, I2 Enterprise, iDIMS, LogEdit, LogPrep, MathPack, OpenBooks, OpenExplorer, OpenJournal, OpenSGM, OpenVision, OpenWorks, PAL, Parallel-VIP, PetroWorks, PlotView, Point Gridding Plus, Pointing Dispatcher, PostStack, PostStack ESP, PROFILE, ProMAX, ProMAX 2D, ProMAX 3D, ProMAX 3DPSDM, ProMAX MVA, ProMAX VSP, RAVE, Reservoir Framework Builder, RMS, SafeStart, SeisCube, SeisMap, SeisModel, SeisWell, SeisWorks, SigmaView, StrataMap, Stratamodel, StratAmp, StrataSim, StratWorks, StressCheck, SynTool, SystemStart, SystemStart for Clients, SystemStart for Servers, SystemStart for Storage, T2B, TDQ, TERAS, TOW/cs, TOW/cs The Oilfield Workstation, Trend Form Gridding, VIP, VIP-COMP, VIP-CORE, VIP-DUAL, VIP-ENCORE, VIP- EXECUTIVE, VIP-Local Grid Refinement, VIP-POLYMER, VIP-THERM, Wellbase, Wellbore Planner, WELLCAT, WELLPLAN, ZAP! and Z-MAP Plus are trademarks of Landmark Graphics Corporation. All other trademarks are the property of their respective owners. Note The information contained in this document is subject to change without notice and should not be construed as a commitment by Landmark Graphics Corporation. Landmark Graphics Corporation assumes no responsibility for any error that may appear in this manual. Some states or jurisdictions do not allow disclaimer of expressed or implied warranties in certain transactions; therefore, this statement may not apply to you. Landmark WELLPLAN Training Manual Contents Introduction ....................................................................................................................... 15 What is WELLPLAN? ................................................................................................. 15 Training Course and Manual Overview ....................................................................... 15 Single User and Network Installations ........................................................................ 16 Basics ................................................................................................................................... 17 Overview............................................................................................................................. 17 Getting Started .................................................................................................................... 18 Starting WELLPLAN .................................................................................................. 19 Projects, Wells, and Cases .................................................................................................. 20 What is a Project, Well and Case? ............................................................................... 20 Database ....................................................................................................................... 20 Creating a Project, Well and Case ............................................................................... 21 Saving and Deleting Cases, Wells, and Projects ......................................................... 22 Main Window Layout ......................................................................................................... 25 Title Bar ....................................................................................................................... 25 Menu Bars .................................................................................................................... 26 File Menu ............................................................................................................... 27 Edit Menu .............................................................................................................. 28 Modules Menu ....................................................................................................... 28 Case Menu ............................................................................................................. 29 Parameter Menu ..................................................................................................... 29 Deviation Menu ..................................................................................................... 29 Wellbore Menu ...................................................................................................... 30 String Menu ........................................................................................................... 30 View Menu ............................................................................................................ 30 Tools Menu ............................................................................................................ 31 Window Menu ....................................................................................................... 32 Help Menu ............................................................................................................. 32 Tool Bars ...................................................................................................................... 32 Wizard .......................................................................................................................... 34 Helpful Features.................................................................................................................. 35 Online Help .................................................................................................................. 35 Configuring Units ........................................................................................................ 35 Tubular Properties ........................................................................................................ 37 Grade ...................................................................................................................... 37 Material .................................................................................................................. 38 Class ....................................................................................................................... 39 Halliburton Cementing Tables ..................................................................................... 39 March 2001 Contents iii WELLPLAN Training Manual Landmark Sound Effects ............................................................................................................... 39 Entering Case Data ............................................................................................................. 40 Two Common Entry Forms ......................................................................................... 40 Entering General Well Information ............................................................................. 40 Designating an Offshore Well ..................................................................................... 41 Defining the Wellbore Geometry ................................................................................ 42 Wellbore Menu ...................................................................................................... 43 Using Catalogs ............................................................................................................. 43 Using a Library ............................................................................................................ 44 Defining a Work String ................................................................................................ 45 Managing Deviation (Survey) Data ............................................................................. 46 Entering Survey Data ............................................................................................. 47 Importing Survey Files .......................................................................................... 47 Setting Survey Options .......................................................................................... 48 Viewing Surveys w/Interpolation .......................................................................... 49 Viewing Surveys w/Tortuosity .............................................................................. 49 Define Fluid Properties and Rheological Model ......................................................... 50 Defining Drilling Fluids ......................................................................................... 50 Define Cement Slurries Tab .................................................................................. 52 Select the Fluid You Want to Use in the Analysis ................................................ 52 Specify Circulating System Equipment ....................................................................... 52 Enter Pore Pressure Data ............................................................................................. 54 Enter Fracture Gradient Data ....................................................................................... 54 Enter Undisturbed Temperature Data .......................................................................... 54 Catalogs .............................................................................................................................. 56 Creating a Catalog ....................................................................................................... 56 Configuring the Workspace ................................................................................................ 58 Windows ...................................................................................................................... 58 Window Panes ............................................................................................................. 58 Tabs .............................................................................................................................. 59 Toolbars ....................................................................................................................... 59 What are Data Status Tooltips and Status Messages ................................................... 60 Viewing Data and Analysis Results.................................................................................... 62 Viewing Well Schematics ............................................................................................ 62 Viewing Survey Plots .................................................................................................. 62 Printing and Print Preview ........................................................................................... 63 Plot Properties..................................................................................................................... 64 Changing Curve Line Properties .................................................................................. 64 Changing the Scale ...................................................................................................... 65 Configuring the Axis ................................................................................................... 66 Changing the Grid ........................................................................................................ 66 Changing the Axis Labels ............................................................................................ 67 Changing the Font ........................................................................................................ 67 Changing the Line Styles ............................................................................................. 68 Using Data Markers ..................................................................................................... 68 Configuring the Legend ............................................................................................... 69 iv Contents March 2001 Landmark WELLPLAN Training Manual DEX and File Importing and Exporting ............................................................................. 70 Torque Drag Analysis................................................................................................... 71 Overview............................................................................................................................. 71 Torque Drag Analysis: An Introduction ............................................................................. 72 Starting Torque Drag Analysis .................................................................................... 72 Available Analysis Modes ........................................................................................... 73 Using Normal Analysis....................................................................................................... 74 Purpose and Use ........................................................................................................... 74 Entering Case Data ...................................................................................................... 74 Selecting Analysis Models and Options ...................................................................... 75 Why Use Bending Stress Magnification Factor? ................................................... 76 Defining Operating Conditions .................................................................................... 77 Defining Multiple Fluids ............................................................................................. 77 How does Fluid Flow Change the Forces and Stresses on the Workstring? ......... 78 Using Friction Reduction Devices ............................................................................... 79 Analyzing Results ........................................................................................................ 80 Plots ....................................................................................................................... 80 Tables ..................................................................................................................... 84 Reports ................................................................................................................... 85 Calibrating Coefficients of Friction from Field Data ......................................................... 87 Purpose and Use ........................................................................................................... 87 Starting the Calibrate Friction Analysis Mode ............................................................ 88 Entering Actual Loads ................................................................................................. 88 Calibrating Coefficients of Friction ............................................................................. 88 Using Drag Charts .............................................................................................................. 90 Purpose and Use ........................................................................................................... 90 Start Drag Chart Analysis ............................................................................................ 90 Defining Operating Conditions and Analysis Interval ................................................ 90 Displaying Actual Loads ............................................................................................. 91 Analyzing Results ........................................................................................................ 91 Measured Weight Chart ......................................................................................... 91 Torque Point Chart ................................................................................................. 92 Using Top Down Analysis.................................................................................................. 94 Purpose and Use ........................................................................................................... 94 Selecting Top Down Analysis ..................................................................................... 94 Defining Operating Conditions .................................................................................... 94 Analyzing Results ........................................................................................................ 95 Tables ..................................................................................................................... 95 Reports ................................................................................................................... 96 Plots ....................................................................................................................... 97 Using Stiff String Analysis ................................................................................................. 99 Purpose ......................................................................................................................... 99 When to Use the Stiff String Model ............................................................................ 99 Activating Stiff String Model ...................................................................................... 99 March 2001 Contents v WELLPLAN Training Manual Landmark Analyzing Results ........................................................................................................ 100 Plots ....................................................................................................................... 100 Analysis Mode Methodology.............................................................................................. 102 Normal Analysis .......................................................................................................... 102 Calibrate Friction Analysis .......................................................................................... 104 Drag Chart Analysis ..................................................................................................... 105 Top Down Analysis ..................................................................................................... 107 Supporting Information and Calculations........................................................................... 110 Additional Side Force Due to Buckling ....................................................................... 110 Sinusoidal Buckling Mode ..................................................................................... 110 Helical Buckling Mode .......................................................................................... 110 Axial Force .................................................................................................................. 111 Buoyancy Method .................................................................................................. 112 Pressure Area Method ............................................................................................ 112 Bending Stress Magnification (BSM) .......................................................................... 113 Buoyed Weight ............................................................................................................ 114 Critical Buckling Forces .............................................................................................. 116 Straight Model Calculations .................................................................................. 116 Curvilinear Model .................................................................................................. 117 Loading and Unloading Models ............................................................................ 118 Drag Force Calculations .............................................................................................. 119 Fatigue Calculations .................................................................................................... 121 Establish A Fatigue Endurance Limit For The Pipe .............................................. 122 Derate The Fatigue Endurance Limit For Tension ................................................ 123 Friction Factors ............................................................................................................ 125 Models ......................................................................................................................... 126 Pipe Wall Thickness Modification Due to Pipe Class ................................................. 126 Sheave Friction ............................................................................................................ 127 Side Force for Soft String Model ................................................................................. 128 Soft String Model ......................................................................................................... 130 Stiff String Model ........................................................................................................ 130 Stress ............................................................................................................................ 132 Von Mises Stress ................................................................................................... 132 Radial Stress .......................................................................................................... 133 Transverse Shear Stress ......................................................................................... 133 Hoop Stress ............................................................................................................ 133 Torsional Stress ...................................................................................................... 133 Bending Stress ....................................................................................................... 133 Buckling Stress ...................................................................................................... 133 Axial Stress ............................................................................................................ 134 Stretch .......................................................................................................................... 135 Stretch due to axial load ......................................................................................... 135 Stretch due to buckling .......................................................................................... 135 Stretch due to ballooning ....................................................................................... 136 Tortuosity ..................................................................................................................... 137 Torque .......................................................................................................................... 137 vi Contents March 2001 Landmark WELLPLAN Training Manual Twist ............................................................................................................................ 139 Viscous Drag ................................................................................................................ 140 References........................................................................................................................... 143 General ......................................................................................................................... 143 Bending Stress Magnification Factor .......................................................................... 143 Buckling ....................................................................................................................... 143 Fatigue ......................................................................................................................... 144 Sheave Friction ............................................................................................................ 144 Side Force Calculations ............................................................................................... 144 Stiff String Model ........................................................................................................ 145 Hydraulics Analysis ...................................................................................................... 147 Overview............................................................................................................................. 147 Hydraulics Analysis: An Introduction ................................................................................ 148 Starting Hydraulics Analysis ....................................................................................... 148 Available Analysis Modes ........................................................................................... 148 Using Pressure: Pump Rate Range Analysis Mode ............................................................ 150 Select Pressure Pump Rate Range Analysis Mode ...................................................... 150 Entering Case Data ...................................................................................................... 150 Define Fluid Properties and Rheological Model ......................................................... 151 Fluid Selector Tab .................................................................................................. 151 Specify the Undisturbed Temperature Profile ............................................................. 152 Eccentricity .................................................................................................................. 152 Specify Circulating System Equipment ....................................................................... 153 Define Pump Rate Range ............................................................................................. 155 Specify Nozzle Configuration ..................................................................................... 156 Set ECD Calculation Depths ........................................................................................ 158 Analyzing Results ........................................................................................................ 158 Plot ......................................................................................................................... 159 Report Options ....................................................................................................... 159 Report ........................................................................................................................... 160 Using Pressure: Pump Rate Fixed Analysis Mode ............................................................. 161 Starting Pressure Pump Rate Fixed Analysis Mode .................................................... 161 Entering Case Data ...................................................................................................... 161 Enter Pore Pressure Data ............................................................................................. 162 Enter Fracture Gradient Data ....................................................................................... 162 Define Pump Rate to Analyze ..................................................................................... 162 Analyzing Results ........................................................................................................ 163 Plots ....................................................................................................................... 163 Using Annular Velocity Analysis Mode............................................................................. 166 Select Annular Velocity Analysis Mode ..................................................................... 166 Entering Case Data ...................................................................................................... 166 Define Pump Rates to Analyze .................................................................................... 167 Analyzing Results ........................................................................................................ 167 Plots ....................................................................................................................... 167 March 2001 Contents vii WELLPLAN Training Manual Landmark Table ...................................................................................................................... 169 Using Swab/Surge Tripping Schedule ................................................................................ 171 Starting Swab/Surge Tripping Schedule Analysis ....................................................... 171 Entering Case Data ...................................................................................................... 171 Specify Circulating System Equipment ....................................................................... 172 Define Analysis Constraints ........................................................................................ 172 Analyzing Results ........................................................................................................ 173 Report Options ....................................................................................................... 173 Report ..................................................................................................................... 173 Using Swab/Surge Pressure and ECD Analysis Mode ....................................................... 175 Starting Swab/Surge Pressure and ECD Analysis Mode ............................................. 175 Entering Case Data ...................................................................................................... 175 Specify Circulating System Equipment ....................................................................... 176 Defining Operations Constraints ................................................................................. 176 Analyzing Results ........................................................................................................ 177 Plots ....................................................................................................................... 177 Report Options ....................................................................................................... 178 Report ..................................................................................................................... 178 Using Graphical Analysis Mode......................................................................................... 179 Starting Graphical Analysis Mode ............................................................................... 179 Entering Case Data ...................................................................................................... 179 Specify Circulating System Equipment ....................................................................... 179 Enter Pump Specifications ........................................................................................... 180 Analyzing Results ........................................................................................................ 180 Plots ....................................................................................................................... 180 Using Optimization Planning Analysis Mode .................................................................... 188 Selecting Optimization Planning Analysis .................................................................. 189 Entering Case Data ...................................................................................................... 189 Specify Circulating System Equipment ....................................................................... 189 Specify Solution Constraints ....................................................................................... 190 Set ECD Calculation Depths ........................................................................................ 191 Analyzing Results ........................................................................................................ 191 Report Options ....................................................................................................... 191 Reports ................................................................................................................... 192 Using Optimization Well Site Analysis Mode ................................................................... 193 Starting Optimization Well Site Analysis .................................................................... 193 Enter Case Data ........................................................................................................... 193 Enter Analysis Dialog .................................................................................................. 194 Using Weight Up Analysis Mode ....................................................................................... 195 Starting Weight Up Analysis ....................................................................................... 195 Enter Case Data ........................................................................................................... 195 Enter Analysis Data and Calculate Data ...................................................................... 195 Using Hole Cleaning Operational Analysis Mode ............................................................. 197 Starting Hole Cleaning Operational Analysis .............................................................. 197 Enter Case Data ........................................................................................................... 197 Enter Analysis Data ..................................................................................................... 198 viii Contents March 2001 Landmark WELLPLAN Training Manual Analyzing Results ........................................................................................................ 198 Plot ......................................................................................................................... 198 Report ..................................................................................................................... 200 Using Hole Cleaning Parametric Analysis Mode ............................................................... 202 Starting Hole Cleaning Parametric Analysis ............................................................... 202 Enter Case Data ........................................................................................................... 203 Entering Transport Analysis Data ................................................................................ 203 Analyzing Results ........................................................................................................ 204 Plots ....................................................................................................................... 204 Supporting Information and Calculations........................................................................... 207 Backreaming Rate (Maximum) Calculation ................................................................ 207 Bingham Plastic Rheology Model ............................................................................... 207 Bit Hydraulic Power .................................................................................................... 211 Bit Pressure Loss Calculations .................................................................................... 212 Derivations for PV, YP, 0-Sec Gel and Fann Data ...................................................... 212 ECD Calculations ........................................................................................................ 213 Graphical Analysis Calculations .................................................................................. 214 Hole Cleaning Methodology and Calculations ............................................................ 215 Bit Impact Force .......................................................................................................... 221 Nozzle Velocity ........................................................................................................... 222 Optimization Planning Calculations ............................................................................ 222 Optimization Well Site Calculations ........................................................................... 223 Power Law Rheology Model ....................................................................................... 226 Pressure Loss Analysis Calculations ........................................................................... 231 Pump Power Calculations ............................................................................................ 232 Pump Pressure Calculations ......................................................................................... 233 Shear Rate and Shear Stress Calculations .................................................................... 233 Swab/Surge Calculations ............................................................................................. 234 Tool Joint Pressure Loss Calculations ......................................................................... 236 Weight Up Calculations ............................................................................................... 237 References........................................................................................................................... 238 General ......................................................................................................................... 238 Bingham Plastic Model ................................................................................................ 238 Coiled Tubing .............................................................................................................. 238 Hole Cleaning .............................................................................................................. 238 Herschel Bulkley Model .............................................................................................. 239 Optimization Well Site ................................................................................................ 239 Power Law Model ........................................................................................................ 239 Rheology Thermal Effects ........................................................................................... 239 Surge Swab .................................................................................................................. 240 Tool Joint Pressure Loss .............................................................................................. 240 Well Control Analysis................................................................................................... 241 Overview............................................................................................................................. 241 Well Control Analysis: An Introduction............................................................................. 242 March 2001 Contents ix WELLPLAN Training Manual Landmark Starting Well Control Analysis .................................................................................... 242 Available Analysis Modes ........................................................................................... 243 Using Expected Influx Volume Analysis Mode ................................................................. 244 Starting Expected Influx Volume Analysis Mode ....................................................... 244 Enter Case Data ........................................................................................................... 244 Specify Choke and Kill Line Use ................................................................................ 245 Enter Temperature Profile for Well Control Analysis ................................................. 245 Determining Type of Kick ........................................................................................... 247 Estimating Influx Volume ........................................................................................... 248 Analyzing Results ........................................................................................................ 250 Influx Volume Estimation Results Tab ................................................................. 251 Plots ....................................................................................................................... 251 Using Kick Tolerance Analysis Mode................................................................................ 252 Enter Case Data ........................................................................................................... 252 Specify Circulating System Equipment ....................................................................... 253 Enter Pore Pressure Data ............................................................................................. 253 Enter Fracture Gradient Data ....................................................................................... 253 Specify Kill Method, Choke/Kill Line and Slow Pumps Data .................................... 253 Enter Choke/Kill Data ........................................................................................... 253 Select Kill Method and Enter Operational Data .................................................... 254 Enter Kill Rate, Kick Data ........................................................................................... 254 Analyzing Results ........................................................................................................ 255 Plots ....................................................................................................................... 255 Animation .............................................................................................................. 260 Using Kill Sheet Analysis Mode ........................................................................................ 262 Enter Case Data ........................................................................................................... 262 Enter Kill Sheet Data ................................................................................................... 263 Enter Kick Analysis Parameters ............................................................................ 263 Enter Mud Weight Up Data ................................................................................... 263 Enter Annular Volumes ......................................................................................... 264 Enter String Volumes ............................................................................................. 265 Select Kill Pump Speed ......................................................................................... 265 Analysis Results ........................................................................................................... 266 Plots ....................................................................................................................... 266 Reports ................................................................................................................... 267 Analysis Mode Methodology.............................................................................................. 268 General Assumptions and Terminology ...................................................................... 268 Initial Influx Volume ............................................................................................. 268 Influx Properties Assumptions ............................................................................... 268 Influx Annular Volume and Height ....................................................................... 269 Choke Pressure and Influx Position ....................................................................... 269 Kill Methods .......................................................................................................... 269 Expected Influx Volume .............................................................................................. 270 Kick Tolerance ............................................................................................................. 271 Kill Sheet ..................................................................................................................... 275 Supporting Information and Calculations........................................................................... 276 x Contents March 2001 Landmark WELLPLAN Training Manual Allowable Kick Volume Calculations ......................................................................... 276 Estimated Influx Volume and Flow Rate Calculations ............................................... 276 Gas Compressibility ..................................................................................................... 278 Influx Circulation Model for Kick While Drilling or After Pump Shutdown ............. 280 Influx Circulation Model for Swab Kicks ................................................................... 284 Kick Classification ....................................................................................................... 289 Kick While Drilling ............................................................................................... 289 Kick After Pump Shutdown ................................................................................... 290 Swab Kick .............................................................................................................. 290 Kick After Pump Shut Down Influx Estimation .......................................................... 290 Kick While Drilling Influx Estimation ........................................................................ 293 Kill Sheet ..................................................................................................................... 296 Pressure at Depth of Interest ........................................................................................ 301 Pressure Loss Analysis ................................................................................................ 301 Steady State Circulation Temperature Model .............................................................. 302 Viscosity and Compressibility of Methane .................................................................. 305 References........................................................................................................................... 308 General ......................................................................................................................... 308 Estimated Influx Volume and Flow Rate .................................................................... 308 Gas Compressibility (Z Factor) Model Calculations ................................................... 308 Steady State Temperature ............................................................................................ 308 Surge Analysis ................................................................................................................. 309 Overview............................................................................................................................. 309 Surge Analysis: An Introduction ........................................................................................ 310 What is the Surge Module? .......................................................................................... 310 What is the Difference Between a Transient and Steady-State Model? ...................... 310 When Should I use the Transient Surge Model? ......................................................... 311 Workflow ............................................................................................................................ 313 Using Surge Analysis Mode ............................................................................................... 316 Starting Surge Analysis ............................................................................................... 316 Entering Case Data ...................................................................................................... 316 Define Fluid Properties and Rheological Model ......................................................... 317 Formation Properties .................................................................................................... 317 Cement Properties ........................................................................................................ 318 Eccentricity .................................................................................................................. 318 Specifying Surge Operations and Analysis Parameters ............................................... 319 Analysis Details ..................................................................................................... 321 Calculating Results ...................................................................................................... 324 Specify Diagnostic File Usage ............................................................................... 325 Analyzing Results ........................................................................................................ 326 Plots ....................................................................................................................... 326 Miscellaneous Plots ............................................................................................... 335 Report ..................................................................................................................... 336 Supporting Information and Calculations........................................................................... 337 March 2001 Contents xi WELLPLAN Training Manual Landmark Methodology ................................................................................................................ 337 Pressure and Temperature Behavior of Water Based Muds ........................................ 337 Viscosity Correlations of Oil Based Muds .................................................................. 338 Surge Analysis ............................................................................................................. 338 Two Analysis Regions ........................................................................................... 338 Connecting the Coupled-Pipe/Annulus and the Pipe-to-Bottomhole Regions ...... 341 Open Annulus Calculations ......................................................................................... 342 Mass Balance ......................................................................................................... 342 Momentum Balance ............................................................................................... 342 Coupled Pipe Annulus Calculations ............................................................................ 343 Pipe Flow ............................................................................................................... 343 Annulus Flow ......................................................................................................... 344 Pipe Motion ............................................................................................................ 344 References........................................................................................................................... 346 Transient Pressure Surge ............................................................................................. 346 Validation ..................................................................................................................... 346 Pipe and Borehole Expansion ...................................................................................... 346 Frictional Pressure Drop .............................................................................................. 346 Pressure and Temperature Fluid Property Dependence ............................................... 347 Cementing-OptiCem Analysis ................................................................................. 349 Overview............................................................................................................................. 349 Cementing Analysis: An Introduction ................................................................................ 350 What is Cementing? ..................................................................................................... 350 Workflow ............................................................................................................................ 351 Using Cementing Analysis Mode ....................................................................................... 353 Starting Cementing Analysis ....................................................................................... 353 Entering Case Data ...................................................................................................... 353 Define Fluids Used During the Cement Job ................................................................ 353 Defining Muds and Spacers ................................................................................... 354 Defining Cement Slurries ...................................................................................... 354 Define Job Information ................................................................................................ 356 Specify the Volume Excess % ..................................................................................... 356 Specify the Standoff or Calculate the Centralizer Placement ...................................... 357 Define the Cement Job ................................................................................................. 359 Define Temperatures, Depths of Interest and Offshore Returns Information ............. 364 Specify Additional Analysis Parameters ..................................................................... 366 Analyzing Results ........................................................................................................ 366 What is the Circulating Pressure Throughout the Cement Job? ............................ 367 Is There Free Fall? ................................................................................................. 368 What is the Surface Pressure? ................................................................................ 369 Automatically Adjusting the Flowrate ................................................................... 370 Using Foamed Cement ........................................................................................... 372 References........................................................................................................................... 380 xii Contents March 2001 Landmark WELLPLAN Training Manual Critical Speed ................................................................................................................... 381 Critical Speed Course Overview......................................................................................... 381 Critical Speed: An Introduction .......................................................................................... 382 What is the Critical Speed Module? ............................................................................ 382 Why Use the Critical Speed Module? .......................................................................... 382 Critical Speed Limitations ........................................................................................... 383 Workflow ............................................................................................................................ 384 Using Critical Speed ........................................................................................................... 386 Starting the Critical Speed Module .............................................................................. 386 Opening the Case ......................................................................................................... 386 Entering Case Data ...................................................................................................... 386 Specify the Finite Element Mesh ........................................................................... 386 Defining Analysis Parameters ..................................................................................... 388 Specify the Boundary Conditions .......................................................................... 389 Calculating Results ...................................................................................................... 390 Analyzing the Results .................................................................................................. 390 What are the Critical Rotational Speeds? .............................................................. 390 Where in the BHA are the Large Relative Stresses Occurring? ............................ 391 What Kind of Stress is Causing the Large Relative Stress? .................................. 392 How Do I View the Large Relative Stress at Any Position on One Plot? ............. 393 Supporting Information and Calculations........................................................................... 394 Structural Solution ....................................................................................................... 394 Vibrational Analysis .................................................................................................... 394 Mass Matrix ................................................................................................................. 397 Damping Matrix ........................................................................................................... 397 Excitation Factors ........................................................................................................ 398 References........................................................................................................................... 401 Bottom Hole Assembly ............................................................................................... 403 Bottom Hole Assembly Course Overview.......................................................................... 403 Bottom Hole Assembly Analysis: An Introduction............................................................ 404 What is the Bottom Hole Assembly Module? ............................................................. 404 Why Should I Use the Bottom Hole Assembly Module? ............................................ 404 Bottom Hole Assembly Module Limitations ............................................................... 405 Workflow ............................................................................................................................ 406 Using Bottom Hole Assembly Analysis Mode................................................................... 407 Starting Bottom Hole Assembly Analysis ................................................................... 407 Entering Case Data ...................................................................................................... 407 Specify the Finite Element Mesh ........................................................................... 407 Analyzing a Static Bottom Hole Assembly ................................................................. 408 Defining Analysis Parameters for Static Analysis ................................................. 408 Analyzing Results for the Static (in-place) Position .............................................. 411 Predicting How a Bottom Hole Assembly Will Drill Ahead ....................................... 418 Defining Analysis Parameters for Drillahead Analysis ......................................... 418 Analyzing Drillahead Results ................................................................................ 419 March 2001 Contents xiii WELLPLAN Training Manual Landmark Supporting Information and Calculations........................................................................... 422 Analysis Methodology ................................................................................................. 422 Three Fundamental Requirements of Structural Analysis ..................................... 422 Defining the Finite Element Mesh ......................................................................... 422 Compute the Local Stiffness Matrix and the Global Stiffness Matrix .................. 423 Degrees of Freedom ............................................................................................... 428 Boundary Conditions ............................................................................................. 428 Constructing the Wellbore and Bottom Hole Assembly Reference Axis .............. 431 Calculating the Solution ......................................................................................... 432 Bit Tilt and Resultant Side Force ........................................................................... 432 Drillahead Solutions .............................................................................................. 435 Bit Coefficient ........................................................................................................ 436 Formation Hardness ............................................................................................... 437 References........................................................................................................................... 438 Notebook ............................................................................................................................. 439 Overview............................................................................................................................. 439 Starting Notebook ........................................................................................................ 439 Notebook Analysis Modes ........................................................................................... 440 Miscellaneous Mode ........................................................................................................... 441 Linear Weight .............................................................................................................. 441 Blockline Cut Off Length ............................................................................................ 441 Leak Off Test ............................................................................................................... 442 Fluids Mode ........................................................................................................................ 443 Mix Fluids .................................................................................................................... 443 Dilute /Weight Up ........................................................................................................ 443 Fluid Compressibility .................................................................................................. 444 Hydraulics Mode................................................................................................................. 445 Pump Output ................................................................................................................ 445 Annular ........................................................................................................................ 445 Pipe .............................................................................................................................. 446 Nozzles ......................................................................................................................... 446 Buoyancy ..................................................................................................................... 447 Calculations ........................................................................................................................ 448 Block Line Cut Off Length .......................................................................................... 448 Dilute/Wt Up Fluid ...................................................................................................... 448 Fluid Buoyancy ............................................................................................................ 448 Fluid Compressibility .................................................................................................. 449 Leak Off Test ............................................................................................................... 449 Mix Fluids .................................................................................................................... 449 Pump Output ................................................................................................................ 450 Nozzle Area ................................................................................................................. 450 xiv Contents March 2001 Chapter 1 Introduction What is WELLPLAN? WELLPLAN is a drilling engineering software system to assist with solving engineering problems during the design and operational phases of drilling and completing wells. WELLPLAN 1998.7 is comprised of several modules including Torque Drag Analysis, Hydraulics, Well Control, Surge and Notebook. WELLPLAN can be used in the office or at the well site. WELLPLAN can be installed on a network for use by several individuals, or on an individual “stand alone” computer. Regardless of the installation location or type, data can be transferred between installations. In addition, WELLPLAN is compatible with other LANDMARK software and data can be transferred between a variety of LANDMARK software packages. Training Course and Manual Overview The purpose of this manual is to provide you a reference for entering data and performing an analysis during the class. Perhaps more importantly, you can refer to it after the class is over to refresh your memory concerning analysis steps. This manual contains technical information concerning the methodology and calculations used to develop this software. If you require more technical information than what is presented in this manual, please ask you instructor. The on-line help is very useful, and may assist you while using the software. This training class is designed to be flexible to meet the needs of the attendees. In this manual, there may be information regarding a module that you do not have. Generally, a training course begins with a quick introduction. Following the introduction, time will be spent covering the “Basics”. The basics are common to all of the modules. In this section you will learn how to navigate the system, enter data, and produce output. After the “Basics” have been reviewed, you will begin to look at the individual modules (Torque Drag, Hydraulics, Well Control, Surge and Notebook.) Landmark WELLPLAN 15 Chapter 1: Introduction Single User and Network Installations WELLPLAN can be installed standalone for a single user or site, or installed centrally on a network for multiple users. A typical installation at the rigsite is standalone with all modules installed on a single hard disk drive. Additionally, a backup computer may have WELLPLAN installed on it for use if the main computer becomes unavailable. In the office, a network installation enables most components to be shared centrally on a network drive. A minimum local directory structure is used for storing WELLPLAN data, user unit sets, catalogs and custom report formats. WELLPLAN is licensed software, and requires some form of license in order to operate. For standalone installations, a bitlock may be used. A bitlock is a special hardware device that is plugged into the parallel port (LPT1) of the computer. Network installations can use Network Licensing. Network Licensing uses a lock file configuration to track the number of users using the varies software modules. Network licensing uses a first come-first served principle and users can access WELLPLAN modules if licenses are available. If a license to any WELLPLAN module is not available, a warning message will appear. A license must become available before the module can be used. 16 WELLPLAN Landmark Chapter 2 Basics Overview In this section of the course, you will become familiar with the basic functionality common to all WELLPLAN modules. You will learn how to enter data, generate and print tables, plots, and reports, manage catalogs, configure units, design your workspace, and many other features that will enable you to use the WELLPLAN engineering modules efficiently. To reinforce what you learn in the class lecture, you will have the opportunity to complete exercises designed to prepare you for using the program outside of class. The information presented in this chapter can be used as a study guide during the course and can also be used as a reference for future WELLPLAN use. Landmark WELLPLAN 17 Chapter 2: Basics Getting Started WELLPLAN is installed with several tools and documentation to assist you with using the product. These tools and documentation can be found by using the Start Menu. The default installation will create a program group titled ‘Landmark Drilling & Well Services’. From this group, select ‘Planning’ then ‘WELLPLAN’. From here, you can select the Documentation sub-group, or the Tools sub-group. Using the Documentation sub-group, you may select: l Help - Use to launch the online help. The online help is also accessible from all windows, and dialogs in WELLPLAN. l Install Guide - The installation guide for WELLPLAN can be viewed using this option. l Landmark Home Page - This option can be used to access Landmark Graphics internet home page. l Release Notes - The Release Notes provide useful information about the current release, including: new features, bug fixes, known problems, and how to get support when you need it. l User Guide - The User Guide contains information about using the software. Using the Tools sub-group, you may select: l Bitlock Status - This tool can be used to view the settings of the bitlock installed on the parallel port. l Crpkey Licensing - This tool can be used to view the status and settings of the Crpkey licensing. l Netsecure Licensing -This tool can be used to view the status and settings of the Netsecure licensing. l Report Manager - Use to view or print reports generated using WELLPLAN’s Report Manager utility. l Unit System Upgrade Wizard - Use this tool to upgrade unit systems from earlier versions of WELLPLAN. 18 WELLPLAN Landmark Chapter 2: Basics l WELLPLAN 5 Catalog Import - Use this tool to import catalogs developed using WELLPLAN 5.X. Starting WELLPLAN You can start WELLPLAN in two ways: l Use the Start Menu. Select ‘WELLPLAN’ using Landmark Drilling and Well Services→Planning→WELLPLAN. l Double-click on any desktop shortcut you have configured. After WELLPLAN launches, a splash window appears that displays licensing and version information. Shortly after the display of the splash window, the first WELLPLAN window will appear. The first window to appear when you start WELLPLAN looks similar to the following. At this time, the window contains few menu options, and most of the toolbar buttons are not available for use. You can select an item from the menu using the mouse or the keyboard quick keys. To use the quick keys to select an item, press and hold the ALT key while pressing the underlined character in the menu item. For example, to open the File menu, press ALT F. To use the mouse, click on the menu item. You must select or define a new Case to expand the menu bar options or to activate additional toolbar buttons. The next section in this manual describes how to define the Project, Well and Case you want to analyze. After the Case is defined, we will examine the window more closely. Title Bar Menu Bar Toolbars Landmark WELLPLAN 19 Chapter 2: Basics Projects, Wells, and Cases What is a Project, Well and Case? Projects, wells, and cases are used to logically group related well information. A project is the highest level of organization. A project can refer to a field, company (if you do work for several companies), or another type of grouping you find useful. A well is the next level of grouping, and is usually used to define a well that is to be analyzed. You may want to think of a well as the familiar ‘well file’. It may contain data for the entire well including all hole sections and associated data. However, you are free to use this level of grouping in way you choose. Just as a project can have many wells associated with it, a well can have many associated cases. Cases are used to group within a well. Case data includes a well definition (wellbore, workstring, fluid, etc.), and operating parameters for analysis. For example, you may choose to define a case for each hole section, or for a certain BHA you are analyzing. A case can also be used for sensitivity analysis. You may have two cases that are identical except for the coefficients of friction defined in the wellbore. Database All project, well and case data is saved together in a database. The database file is ‘Wellplan.mdb’ and can be found in the ‘Database’ 20 WELLPLAN Landmark Chapter 2: Basics folder of the folder where you installed WELLPLAN. The database, and storing the information by Project/Well/Case is a major change from WELLPLAN 5.3x versions. Because the database contains all the information you have entered, you should back up your database on a regular basis. If something unfortunate happens to the database you are using, it is always a relief to have a current backup of your database to use to restore your data. Creating a Project, Well and Case Use File →Project to create a project. You can use this dialog to create new projects, to edit the project name and descriptions for existing projects, or to delete existing projects. You can also see the number of wells that are associated with existing projects. Click on the New button to create a project. Give the project any description you want. Close the project dialog. Existing Projects Click New to create a project. The next step is to create a well associated with the project. To create a well, use File →Well. Click on the New button to create a new well. Landmark WELLPLAN 21 Chapter 2: Basics Enter the well name. Select a project with Detail Well Information is which to associate the optional. case. Enter the name and description of the well. Don’t forget to select the correct project from the project drop down list. This step will associate the well with the appropriate project. Although we will be using an existing case, you could create a new case by using File →New Case. On the dialog displayed, select the project and the well you want to associate the case with. This training course uses a Case titled ‘9 5/8”casing’ in the Project ‘Guided Tour’ and Well ‘Tour #1’. Open this case using File→Open Case. Select the project associated with the case you want to open. Select the well associated with the Double-click the case case you want to you want to open. open. Saving and Deleting Cases, Wells, and Projects When a case is created, it will be assigned a default name. In order to assign the case a meaningful name you must save the case. 22 WELLPLAN Landmark Chapter 2: Basics There are two ways to save a case. If a case has been saved before, you can use File →Save to save the case with the same name it was previously been saved with. Use File →Save As to specify the case name. Using this method, you must provide a name for the case. If you try to use File →Save with a case that has not already been saved you will be prompted to enter a meaningful case name. Projects, and wells are saved when they are created. To delete a project, use File →Project. When you delete a project, the associated wells and cases will not be deleted. You must delete the wells and cases separately. Select the project Click Edit to edit the you want to edit or selected project delete. name or description. Click Delete to delete selected project. To delete a well, use File →Well. A dialog listing all wells in the database will be displayed. Highlight the well you want to delete and click the Delete button. All cases associated with this well will also be deleted. Select the well Click Edit to edit the you want to edit or selected well’s delete. name or description. Click Delete to delete selected well. You can delete a case by deleting the well it is associated with or you can use File →Delete →Case. Highlight the case you want to delete and click the Delete button. Landmark WELLPLAN 23 Chapter 2: Basics Select the case you want to delete. Click Delete to delete selected case. 24 WELLPLAN Landmark Chapter 2: Basics Main Window Layout WELLPLAN is designed using a Microsoft Windows MDI (multiple Document Interface) area. The WELLPLAN Main Window is shown below. In this window, a well schematic is currently displayed. In many cases, data entry and reviewing analysis are performed in separate windows that you can view simultaneously within the Main Window. There are several distinct areas within the Main Window as shown in the following figure. Title Bar Menu Bar Module Toolbar Standard Toolbar Graphic Toolbar Wizard Toolbar Window Title Bar Tabs Status Bar Title Bar The Title Bar is located at the top of the Main Window and displays the name of the current project, well and case. Notice the case name that has been assigned. Landmark WELLPLAN 25 Chapter 2: Basics To move the application frame to another part on the screen, drag the title bar using the mouse. To toggle the application frame between its maximized and restored states, double-click the title bar. Individual windows also have Title Bars. They behave much like the application’s title bar in that they contain similar menus and buttons. You can use them to move the window to a different location on the screen. Menu Bars After a case has been created or opened, the menu bar has more selections. We will begin to look at these options more closely. 26 WELLPLAN Landmark Chapter 2: Basics File Menu Use the File Menu to manage data, create new projects, wells, cases and catalogs, delete projects, wells, cases and catalogs, access import/export functions, access print functions, and exit WELLPLAN. { { Display, add, delete or edit projects. Display, add, delete or edit wells. Create a new case. Open an existing case. Creates a new catalog. Open an existing catalog. Access the centralizer editor to add a new centralizer or edit an existing. Close or save the active case or catalog. Create and place on your desktop a shortcut file for the current case. Manage workspace templates. Delete cases and catalogs. Import or export using DEX. Export or import the active project, well, catalog or case data. Export Metafile graph data. Print, preview print or set page formats. View or edit properties of the active case or catalog. Open the most recently closed case or catalog files. Landmark WELLPLAN 27 Chapter 2: Basics Edit Menu Use the Edit Menu to modify the currently open Case. Use the Report Header Setup option to specify the title to use on the output, and to specify the logo (bitmap) to place on the output. Auto-Calculation is an option on the Edit Menu. (You can also find the Auto-Calc and Calculate buttons on the Standard Toolbar. The Calculation button looks like a calculator.) When auto-calculation is turned on, WELLPLAN automatically calculates any new values entered in a dialog after you click OK or Apply. When auto-calculation is turned off, you will need to click the Calculate button when you want data calculated so that you can have accurate results in your views. Remove data or an object you selected and save it to the Clipboard. Paste (insert) the contents of the Clipboard at the location you select Return to the prior version of data on a spreadsheet one change at a time. Add a new row to the active spreadsheet. Copy data or an object you selected and save it to the Clipboard. Customize the currently active pane. Select every row in the active Configure report headings. spreadsheet or table for cutting or Toggle on and off pasting. WELLPLAN’s automatic calculation feature. Use Calculate to calculate when Remove one or more rows from the desired if Auto Calculation is active spreadsheet not turned on. Modules Menu Use the Modules Menu to access the various WELLPLAN modules, including: Torque Drag, Hydraulics, Well Control, Surge and Notebook. 28 WELLPLAN Landmark Chapter 2: Basics Select the engineering module you want to use from the menu. Case Menu Use the Case Menu to enter data specific to the currently opened Case. The contents of the Case Menu will vary depending on the Module chosen. The Case Menu has dialogs and spreadsheets for gathering information pertaining to the case you are defining. Most of the information entered in this menu’s options will be used for many or possibly all modules and module analysis modes. Some Case menu options are only available for gathering information pertaining to specific WELLPLAN modules. Also, the menu options available may vary by analysis mode. You must enter information on all dialogs visible in the Case menu for the selected analysis mode before you can proceed with the analysis. The contents of the Case Menu changes depending on the analysis module selected. Parameter Menu Use the Parameter Menu to enter analysis parameters for the chosen analysis mode. The contents of the Parameter Menu vary depending on the analysis mode chosen. Deviation Menu The Deviation Menu is only available when the Survey Editor is active. Use this menu to import or export surveys to the library. Landmark WELLPLAN 29 Chapter 2: Basics Use the Deviation menu to import or export survey data to/from libraries. Wellbore Menu The Wellbore Menu is only available when the Wellbore Editor is active. Use this menu to display catalog details about the highlighted section of the wellbore, and import or export wellbore data to or from the libraries. The Wellbore Menu is only available when the Wellbore Editor is active. String Menu The String Menu is only available when the String Editor is active. Use this menu to display catalog details or specific information about a workstring component, and to import/export string data to/from the libraries. The String Menu is only available when the String Editor is active. View Menu Use the View Menu to view analysis results, including reports, tables, and plots. Some calculations are also performed using this menu. You can use this menu to toggle on or off toolbars and tabs. From this menu, you can control the use of tips and calculation status messages. 30 WELLPLAN Landmark Chapter 2: Basics The Setup section has options used to display and remove toolbars from view; add, rename, arrange, and delete window tabs; display engineering analysis errors as tooltips; and display a status message window. This section is available for all modules and analysis modes. The Analysis Output section has submenu options used to display plots, tables, and reports for the current analysis mode. The submenus and the options available vary by module and its active analysis mode. The Schematic and Survey Plots section has submenu options used to display wellbore schematics, fluid plots, and survey plots. This section is available for most modules and analysis modes. Setup section Analysis Output section. The contents of this section vary depending on analysis module and mode active. Schematic and Survey Plots section Tools Menu The Tools Menu is used to add, remove, edit, and select unit systems. You can also use this menu to specify grade, material, and class tubular properties. Add, remove, edit, and switch unit systems Specify grade, material, and class tubular properties Click Halliburton Cementing Tables to access an online version of the “Redbook”. Check to turn on sound effects. Landmark WELLPLAN 31 Chapter 2: Basics Window Menu Use the Window Menu to select and arrange windows. Enlarge one of the split window panes so that it fills the entire area. Return back to the original split window configuration after maximizing one of the split window panes. Arrange any windows not minimized in an overlapping fashion. Arrange any windows not minimized horizontally or vertically in non-overlapping tiles. Arrange the icons of any minimized windows to their default positions at the lower left of the window or desktop. Split the active window into four separate panes. Switch between well files when you have two or more open. There will be a check mark beside the active Case or Catalog name. Help Menu Use the Help Menu to view tips, access help, or to view information concerning the version of the WELLPLAN software in use. Help Menu Tool Bars After a case has been created or opened, you can see that the toolbar choices have also been expanded. Toolbars have buttons you can use to 32 WELLPLAN Landmark Chapter 2: Basics quickly perform common operations, such as file management commands and engineering functions. There are several toolbars. Each toolbar is outlined by a single line, so you can tell what is included in each toolbar. Toolbars are normally found just below the menu bar, but they can be “undocked” and moved to other areas within the application window. They can also be removed from view using View →Toolbars. Toolbar buttons are grayed out when they are not applicable to what you are currently doing. The Standard Toolbar provides easy access to common file management and printing commands. Save active Auto Case or Print Priview Cut Calculate Catalog Calculate Undo New Case Open Case Print Paste Maximize/Restore Copy Help The Module Toolbar provides access to the engineering modules. You can also access the engineering modules by using the Modules Menu. Well Control OptiCem - Cementing Torque Drag Surge Bottom Hole Assembly Hydraulics Notebook Critical Speed The Graphics Toolbar provides access to graphical functions and is only available when a plot is active in the current window. If the Graphics Toolbar is grey, click once on the plot and the toolbar selections will become available. Landmark WELLPLAN 33 Chapter 2: Basics turns off the functions enabled Data Reader Legend by some Graphics Swap Axis toolbar buttons Properties Rescalae Grid View Line Highlighting Wizard The Wizard Toolbar provides access to analysis modes, and data entry forms. Mode drop-down list to select desired Wizard Drop-down analysis mode. list to guide you through data entry Previous and Next buttons 34 WELLPLAN Landmark Chapter 2: Basics Helpful Features Online Help The Help Menu has several available options. Help can be accessed by pressing the F1 key, selecting Help from the Menu bar, or by clicking the Help button available on many dialogs. Tip of the Day is a series of brief, helpful tips that are displayed when you start WELLPLAN. If you don’t want to see the tips, turn them off using this menu option. Contents displays the online help topics grouped together in a logical format. If you choose ‘Search for Help on...’ you can view an index of the help. For example, to find help on the toolbars, type toolbar in the first line, and then select toolbars. You can find help on any of the WELLPLAN toolbars using this help screen. Use About WELLPLAN 1998.7 to determine what version and build number you are using. This is very helpful information if you are contacting WELLPLAN support. Click to access the help Configuring Units WELLPLAN is distributed with two units systems (API and SI). Each unit system is on a separate tab. You can not edit or change the API or SI units systems. However, you can use these unit sets as the basis for a new unit system you are defining. At any time, you may change the Landmark WELLPLAN 35 Chapter 2: Basics display units, and the value will automatically be converted without lose of data quality. Units systems are selected or edited using the Tools→Units System Editor tabs. On each tab, you can see the unit each parameter will use in the analysis. Changing units is easy. Launch the Unit Editor, select a unit system (API, SI, or custom defined), and then click a Unit Class on the left side of the tab. Choose from a list of units from that class on the right side of the tab. Click on the unit you want to use. You can make as many changes as you need. When you are finished making changes, click OK to apply the changes. The name of the active unit system is displayed in the lower right side of the Status bar. This unit system is currently being used in the analysis. Holding the cursor over the status bar will display the description of the selected unit system. Double-clicking the unit system name in the status bar will activate the unit systems editor, or you can use Tools→Units System Editor and click on the tab for the desired system and click the OK button. In WELLPLAN, only some units are meaningful for expressing unit types. For this reason, Unit Class (sets of units for a particular unit type) are defined. Examples of unit classes are: diameters, depth, and dogleg severity. Each data entry field in WELLPLAN belongs to a Unit Class and its value is displayed in the unit defined for that class. Variables that belong to different classes do not need to be represented in the same type of units. For example, while Hole Diameter might be represented in inches (API), Hold Depth might be represented in meters (SI). 36 WELLPLAN Landmark Chapter 2: Basics Click the New button to create a Active unit set is the unit system tab displayed on top of other tabs. Click on the tab to Click the Edit activate it. button to edit a unit set you have created. You can not edit the API or SI unit sets. Click the Delete button to delete a unit set that you have created Tubular Properties Tubular properties can be changed using the Tools menu. Tubular properties include material, grade and class. These properties are used to describe the well tubulars and other components used in the wellbore and workstring editors. You can add additional properties, edit existing properties, or delete entire rows as you can with any spreadsheet in the system. Grade Grade is used to define the strength of the tubular or component. Landmark WELLPLAN 37 Chapter 2: Basics Select the section type from the drop down list You must enter data in each column to define a tubular grade To delete an item, click on the row number of the selection that you want to delete, then click the Delete button To insert a row, you can add to the bottom of the existing list. You can also select the row below where you want to insert a row and then click the Insert button. Material Material is used to define the density of the material, Young’s modulus and Poisson’s ratio for tubular and other components. Select the section type from the drop down list You must enter data in each column to define a material To delete an item, click on the row number of the selection that you want to delete, then click the Delete button To insert a row, you can add to the bottom of the existing list. You can also select the row below where you want to insert a row and then click the Insert button. 38 WELLPLAN Landmark Chapter 2: Basics Class Class is used to define the wall thickness percentage of tubulars. The percentage of wall thickness is used to calculate the existing outside diameter of the tubular. You must enter data in each column to define a tubular class To delete an item, click on the row number of the selection that you want to delete, then click the Delete button To insert a row, you can add to the bottom of the existing list. You can also select the row below where you want to insert a row and then click the Insert button. Halliburton Cementing Tables Click on Halliburton Cementing Tables to access an online version of the traditional Redbook. You can use the Cementing Tables to determine hole capacities, tubular/casing displacements, tubing/casing stregth and dimensions, volumes between tubing and casing, etc. Sound Effects This menu option lets you toggle (on or off) any sound effects related to Wellplan program operation. When the menu option is checked, sound effects are ON. When the menu option is unchecked, sound effects are OFF. Landmark WELLPLAN 39 Chapter 2: Basics Entering Case Data The Case menu (a selection on the menu bar) is used to enter data defining the well including the wellbore, workstring, fluid, etc. The contents of the Case menu will change depending on the type of analysis you have selected because analysis types require different information about the well. Later on we will see the Parameter menu which is used to enter analysis parameters specific to the analysis type you are performing. It is recommended that you begin entering data in the first menu item available on the case menu and work your way down the menu selections. You can also use the Wizard Toolbar to enter data in the proper order. Two Common Entry Forms Dialogs and spreadsheets are the two types of data entry forms used in WELLPLAN. When a dialog is active, you can not enter data anywhere else in the program until the dialog is closed. Spreadsheets are used for repeating sets of data. Much of the functionality of these data entry forms will be intuitive to you because it is similar to other Windows applications. However, if you have a question concerning the use of these data entry forms, refer to the online help. Entering General Well Information The Case →General dialog contains three tabs. On the first tab, you specify the well’s total depth, vertical section definition, reference elevation, and whether the well is offshore or deviated. On the second tab, you can specify information about the cementing job. This information is optional. You may enter comments about the well on the third, but this information is optional. 40 WELLPLAN Landmark Chapter 2: Basics Check box to specify Specify the Well offshore well Measured Depth Check box to specify a TVD is calculated deviated well Select the well Specify the Vertical depth reference Section point from the drop down list The Elevation is the height of the reference point above MGL for an onshore well or MSL for an offshore well. For an offshore well, the RKB elevation along with the water depth entered on the Offshore dialog will determine the mudline depth. This field will be disabled and assigned a value of 0 if the reference depth is MGL or MSL. Note: Depths based on a given elevation are not automatically re-computed if the elevation is changed. For example, the hanger, shoe, and TOC fields are not automatically changed to reflect a change in the elevation field. The Job Information tab is used to enter additional information about the job, including pipe size, job type/description, and date. This information is optional and pertains primarily to the OptiCem- Cementing module. Designating an Offshore Well The Case →Offshore dialog is used to specify the water depth and well type (platform or subsea) for an offshore well. You can not access this dialog unless you have indicated that the well is an offshore well on the General Dialog. Landmark WELLPLAN 41 Chapter 2: Basics Click radio button to select Platform or Subsea well Defining the Wellbore Geometry The Case →Wellbore dialog is used to define the wellbore geometry, including casing, drillpipe, open hole, riser, or tubing sections for the current case. Wellbore Menu Each row defines a wellbore section For cased sections, specify the effective hole diameter of the hole into which the casing is inserted. (Do NOT enter the casing OD.) This diameter is used for surge calculations to compute the elastic properties. For open hole sections, the effective hole diameter is used to represent the actual size of the hole. Volume Excess % is calculated based on effective hole diameter. Since a project can have multiple cases, you need to enter data in this spreadsheet to define the well profile and well depth of a particular case for analysis. From this data, you can define the components of the wellbore and the material properties of the components. The wellbore configuration is common for all modes and is available across all WELLPLAN modules. You must enter the wellbore information from the surface down to the bottom of the well. When you make a selection from a Section Type cell 42 WELLPLAN Landmark Chapter 2: Basics (other then Open Hole), a dialog specific to that section type appears. You must fill in the data in the dialog in order for that section type to be recorded in that cell. You also must fill in all editable cells in the spreadsheet row. NOTE: For cased sections, specify the effective hole diameter of the hole into which the casing is inserted. (Do NOT enter the casing OD.) This diameter is used for surge calculations to compute the elastic properties. For open hole sections, the effective hole diameter is used to represent the actual size of the hole. Volume Excess % is calculated based on effective hole diameter. If you import a caliper log into Wellplan, you should double- check the values for any rows labeled Open Hole. The Import Caliper Log function takes the number of blocks specified by the user and creates the same number of rows in the spreadsheet, averaging the individual measured hole diameters into each section described in the spreadsheet. Logs that start at the bottom of the casing may not continue all the way to the top of the well, in which case the first geometry may need to be added to the top of the outer geometry table after performing the import. Washed out portions of a well may cause the caliper to record values such as - 999.0, which represents an unknown value. If any value is blank, you must enter an appropriate diameter by typing it into the spreadsheet. Wellbore Menu When the Wellbore Editor is visible, the Menu Bar has an additional menu option available. This menu option titled Wellbore is used to access the catalog and to import to or export from the library. The wellbore and survey editors have similar menu items when active. Using Catalogs Catalogs contain data that you can use to create a workstring or wellbore. There is a different catalog for each component type, and thirteen default catalog types are included with the system that contain many tubular and tool components. Default catalogs for each type are distributed with WELLPLAN, but you can create your own catalog to include a component that may not be available in the default catalogs. We will create a new catalog later in the course. Landmark WELLPLAN 43 Chapter 2: Basics Catalogs do not belong to a particular case. You can use the same catalogs for all projects, wells and cases you create. You can export catalogs to other users of WELLPLAN. Most catalogs require you to select an item by choosing one descriptive item from several columns of data. In order to select an item from the column, you must double click on the item. Select the catalog type from the drop down list. Select one item from each column by double clicking the left mouse button on the item. Using a Library Libraries are used to copy wellbores, workstrings and fluids between cases. You can create a library by exporting the desired wellbore, workstring or fluid. A copy is made in the library. To use a library entry in another case, you must import it into your workstring, wellbore, or fluid editor. After the library is imported, you can edit it as you need. A common use of libraries would be to create a library of several frequently used bottom hole assemblies. BHAs are typically tedious to enter, and utilizing the library feature can significantly reduce the required time to enter a BHA into the workstring editor. Do not confuse libraries with catalogs. A catalog contains a selection of data that you may use to create a workstring or wellbore. After a workstring or wellbore is created, you may want to export it to the library for use in other cases. 44 WELLPLAN Landmark Chapter 2: Basics Defining a Work String The Case → String spreadsheet is used to define all types of tubular work strings and their components. Casing, liner, tubing and drill strings are all defined using this spreadsheet. Strings can be entered from the top down or from the bottom up. String depth is an important item on this form, and indicates the bit depth used in many of the analysis modes. Workstrings can be entered entirely, or can be based on a string stored in a library. To import a string from the library, use String →Import From Library. Select the project and well containing the string you want to import, and then select the desired string. String menu Edit menu Select string type. Enter string depth. It will be used in many analysis modes. Select string entry order To edit or view information concerning a particular component, click on any data cell pertaining to the component and then use String →Data. Landmark WELLPLAN 45 Chapter 2: Basics Use Tools →Tubular Properties to edit the tubular material types, material properties, grades, or class. You can change much of the information describing the component on the Data dialog, however these changes are not made to the catalog entry corresponding to the component. You must use File →Open Catalog to change the catalog entry. On the component data dialog there are some material property cells that can not be edited. This information is related to the grade and material selected for the component from the drop down lists. Use Tools →Tubular Properties to add or edit component material types, grades, or class. Managing Deviation (Survey) Data The Case →Deviation menu item has a submenu. Use these menu choices to enter survey data, apply tortuosity to the surveys, define survey calculation methods, and import survey information from another source. There are two deviation menus. One is available from the Case Menu, and the other is available on the Menu Bar when the Survey Editor is active. The Deviation menu on the Menu Bar contains import to and export from library functions. Deviation menu 46 WELLPLAN Landmark Chapter 2: Basics Entering Survey Data Use Case →Deviation → Survey Editor to enter survey data points. You must specify measured depth, inclination and azimuth. The rest of the information displayed in the non-editable cells will be calculated for you. Survey data is calculated using the minimum curvature method. Deviation menu on Menu Bar is used to import or export survey data to/from libraries. Enter MD, INC, and AZ. The remaining fields are calculated Importing Survey Files You can also import survey data points using Case →Deviation →Import Survey File. This is useful if you have survey data from a source other than another Landmark software product. A survey file must meet the following requirements to be imported using this option. • The data must be in ASCII format or reside in the Windows Clipboard. If you are using the Clipboard to import from Excel, use ‘Tab’ as the column delimiter. • The data must be in columns, each separated by a comma, tab, or blank space. • Each row must have the same format. • The measured depth, inclination and azimuth must be in a supported unit. If you are importing data from Compass, you would use the Clipboard. To import data from DIMS or another Landmark product, you should use DEX import. The DEX import will be discussed later. Landmark WELLPLAN 47 Chapter 2: Basics Specify data order Specify data units Import from a file or from the clipboard Setting Survey Options You can add tortuosity to survey data points. Tortuosity is designed to apply a “rippling” to a planned wellpath to simulate the variations found in actual wellpath surveys. Tortuosity should never be applied to actual survey data. The three tortuosity methods available are sine wave, random inclination dependent azimuth, and random inclination and azimuth. The sine wave modifies the inclination and azimuth of the survey based on the concept of a sine wave shaped ripple running along the wellbore. The random methods apply random variation to the inclination and azimuth. This method is based on SPE 19550. Click one radio The magnitude is button to select the maximum tortuosity method variation of angle that will be applied to the inclination For the Sine Wave and azimuth of the method this is the native (untortured) wavelength of the survey. ripple. For the Random methods, the Angle Change Period is used to normalize the measured depth Survey data will be calculated at the interval specified. distance between survey points. 48 WELLPLAN Landmark Chapter 2: Basics Viewing Surveys w/Interpolation The survey data displayed using Case →Deviation → Surveys w/Interpolation is a read-only view of the interpolated survey data set. If interpolation is not applied in the Survey Options dialog, a default interval of 30 ft will be used. Interpolated survey data is added to the surveys specified in the survey editor. Most cells in this spreadsheet are read only. Viewing Surveys w/Tortuosity Case →Deviation → Surveys w/Tortuosity data is only available if tortuosity has been applied using the Survey Options dialog. This spreadsheet displays a read-only view of the surveys that have had tortuosity applied. Landmark WELLPLAN 49 Chapter 2: Basics Most cells in this spreadsheet are read only. Define Fluid Properties and Rheological Model Defining Drilling Fluids Use the Case→Fluid Editor→Standard Fluids tab to define drilling fluids. There are three rheological models to choose from, including: Power Law, Bingham Plastic, and Herschel Bulkley. For each model you can choose to enter PV/YP data or Fann data. You may also choose to export a fluid to a library, or input a fluid from the library. However, the library functions are not accessed via the main menu, but by clicking buttons directly on the dialog. 50 WELLPLAN Landmark Chapter 2: Basics Click New to define a new fluid. You will be prompted to enter a name for the fluid. Library import and export buttons Use the fluid list box to display data defining an existing fluid, remove an existing fluid or to rename an existing fluid. To display data defining an existing fluid, highlight the fluid name. To delete a fluid, highlight the fluid name and click the Delete key. To rename an existing fluid, click the fluid name and then click again. Type over the existing name to provide a new name. Click the New button to add a test data for a new temperature. Click on an existing temperature to edit or view test data for that temperature. Click Plot Rheology Tests to plot rheology tests for all temperatures. Click Save Fann Defaults to save the Fann defaults when you plot rheology tests. Tuned spacer is not available in the commercial version of WELLPLAN. Shear rates and shear stresses are calculated directly from the Fann data specified. Shear rate and shear stress data. Company and Field are optional. Specify the density of the fluid. Select the fluid type from the drop down list. Choose the rheology data you want to enter from the drop down list. Specify whether the fluid is oil or water based. Select the rheology model. Type rheology test data. Landmark WELLPLAN 51 Chapter 2: Basics Define Cement Slurries Tab The Case→Fluid Editor→Cement Slurries tab is only available when using the Cementing-OptiCem module. This tab is discussed in the Cementing-OptiCem section of this course. Select the Fluid You Want to Use in the Analysis Use the Case→Fluid Editor→Fluid Selector tab to select the fluid you want to use in a Torque Drag, Hydraulics or Well Control analysis. If you are performing another type of analysis, this tab is not applicable. Select the fluid you want to use from the drop down list. Only fluids that have been defined are listed in the drop down list. Select the fluid you want to use in the analysis from the drop down list. Specify Circulating System Equipment Use the two tabs on the Case →Circulating System dialog to specify surface equipment and mud pumps data. On the Surface Equipment tab, you may choose one of four pre-defined surface equipment configurations. 52 WELLPLAN Landmark Chapter 2: Basics Click the Specify Pressure Loss radio Enter the rated button to enter the maximum working expected pressure pressure loss through the surface equipment. Select the category of surface equipment Or, you can calculate that you want to use the surface equipment from the drop down pressure loss by list. You don’t need clicking the Calculate to select or specify a Pressure Loss radio surface equipment button. configuration if you specify the pressure If you want to loss. calculate the pressure loss, you must select/specify the surface equipment configuration. Use the Pumps tab to enter information pertaining to all pumps available. You may indicate which pump(s) are currently active by clicking the Active check box. Check box to specify active pump Insert a new row by entering data in the next empty row, or by highlighting a row and pressing the Insert key on your keyboard. Delete a row by highlighting it and pressing the Delete key on your keyboard. Landmark WELLPLAN 53 Chapter 2: Basics Enter Pore Pressure Data Use the Case →Pore Pressure spreadsheet to define the pore pressure profile as a function of vertical depth. You may enter either pressure or EMW (ppg) for a vertical depth and the other value will be calculated based on vertical depth. You may enter several rows of data to define many pore pressure gradients. Enter Pore Pressure, and EMW will be calculated, or enter EMW and Pore Pressure will be calculated Enter Fracture Gradient Data Use the Case →Frac Gradient spreadsheet to define the fracture pressure profile as a function of vertical depth. You may enter either pressure or EMW (ppg) for a vertical depth and the other value will be calculated based on vertical depth. You may enter several rows of data to define many fracture gradients. Enter Frac Pressure, and EMW will be calculated, or enter EMW and Frac Pressure will be calculated Enter Undisturbed Temperature Data Use the Case →Undisturbed Temperature tabs to define the undisturbed temperature profile as a function of depth. The Standard tab 54 WELLPLAN Landmark Chapter 2: Basics is used to specify basic formation temperature data. The well temperature at total depth can be specified, or it can be calculated from a gradient. Click here to specify temperature at TD Click here to specify a gradient to use to calculate temperature The Additional tab can be used to add temperatures to characterize a non-linear formation or seawater profile. These temperatures must be entered on a true vertical depth basis. Intermediate temperatures are linearly interpolated between specified points. Enter temperatures based on TVD Landmark WELLPLAN 55 Chapter 2: Basics Catalogs Creating a Catalog We have used the catalog to design a wellbore and workstring. However, if a necessary tubular or component is not in the default catalogs distributed with WELLPLAN you must create a new catalog. The required component can be added to the new catalog. There are two ways to create a catalog that you can add components to. You can create a completely new catalog using File→New Catalog or you can save one of the default catalogs using a new name. Saving with a new name creates a new catalog containing all items in the default catalog. Renaming a default catalog, and then editing that catalog is the most common method. To rename a catalog, you must first open the catalog using File→Open Catalog. Select the catalog type Select the catalog you want to open After the catalog is open, use File→Save As. At this point you can give the catalog a name, and a short description. Specify name of catalog After the catalog is renamed, all data cells become editable, and you can add, edit or delete as needed. Don’t forget to save the file again after you make the necessary changes. 56 WELLPLAN Landmark Chapter 2: Basics To access the new catalog, add a component as you normally would to the wellbore or the workstring. First select the component type you want to add. From the dialog that appears, select new catalog from the drop down list of catalogs. Select desired catalog from drop- down list. Landmark WELLPLAN 57 Chapter 2: Basics Configuring the Workspace Windows Each open case occupies one window, and each window belongs to one case. A window can contain one or more screen layers, which are selected using the tabs along the bottom edge of the window. Each layer contains one or more window panes, and each pane can contain different contents. In addition, each pane may contain scroll bars, which become active when the contents are too large to fit inside the frame. The frame governs the amount and location of the screen space taken up by each window. It is the thin gray border around each pane and around the window. Windows always exist in one of three states: • Maximized: the window takes up all of the available space within the application frame • Minimized: an icon within the application frame • Restored: original size and position If a window is in its restored state, it will have a Title Bar. The Title Bar is the thick colored band along the top of the window. The center of the title bar contains the name of the active spreadsheet, table, plot, or schematic, and the name of the case to which the window belongs. The left edge of the title bar contains the Window Control Menu, and the right edge contains three buttons. The first is the Minimize button, the second is the Maximize button, and the third is the close button. At any given time there is one and only one active window, and it belongs to the active case. A colored title bar denotes the active window; all others are gray. Window Panes Each window contains one or more layers, and each layer can contain different information. A pane frames information, such as a well schematic, spreadsheet, table or plot. Light gray dividers denote panes. By default, each layer contains only one pane, but you can split this into 58 WELLPLAN Landmark Chapter 2: Basics up to four panes using the window splitters located at the ends of the scroll bars. To vertically split the screen, the splitter is in the lower left corner of the windowpane. To horizontally split the screen, the splitter is in the upper right corner of the windowpane. Tabs Each window contains one or more layers (tabs), and each layer can contain different information. Only one layer is visible at any given time. To switch between layers, simply select the tab with which it is associated using the mouse. Tabs are arranged along the lower left edge of the window, a region that they share with the window’s horizontal scroll bars. You can control the amount of space allocated to each using a splitter. As you drag this splitter left and right, the amount of room available in which to display tabs grows and shrinks. If there is not enough room to display all of the tabs, you can scroll through them using the tab scroll buttons. Note that you can add, delete, rename and re-order tabs using the View Menu Tabs Option dialog. You can also double click on the tab, and the Rename Tab dialog will appear. Tab configuration can be saved using File→Workspace→Save Template option. Toolbars Use View→Toolbars command to enable or disable the Standard, Module and Graphics toolbars. To enable or disable a toolbar, simply click on the appropriate check box, which will either add it or remove it from the screen. By default, all toolbars are normally displayed directly below the menu bar. Although the print preview toolbar will not be displayed until you select File→Print Preview. However, all toolbars are dockable, which means they can be moved around the screen and adjusted to fit your needs. To induct a toolbar, click anywhere on the toolbar’s light grey border and drag it away from its original position. After you release the mouse button, the toolbar resides in a palette window which “floats” above the application frame. After a toolbar has been undecked, it can be moved Landmark WELLPLAN 59 Chapter 2: Basics to another portion of the screen by clicking anywhere in its light gray border, or title bar and then dragging it. To re-dock an undocked toolbar, simply drag it to any edge of the application frame. When the toolbar approaches a valid docking position, its border will suddenly change. At this point, you can release the mouse button. After you release the mouse button, the positions of any overlapping toolbars will be adjusted to accommodate the new toolbar. Click to turn on the toolbar. What are Data Status Tooltips and Status Messages On the View menu, click on this option to toggle the functionality between active and inactive. If the option is active, a check mark will be visible beside the option. If this option is active, the last engineering analysis error (if any) will be displayed as a tooltip when the mouse is placed over a calculated field in a Quick Look section of a dialog. If the dialog doesn’t have a Quick Look section, this option does not apply. When View→Status Messages is active, a message window at the bottom of the active window indicating any error messages generated from analysis results. 60 WELLPLAN Landmark Chapter 2: Basics Status messages and Tool Tips indicate that Pump Pressure can not be zero. Tool Tip Status Message Landmark WELLPLAN 61 Chapter 2: Basics Viewing Data and Analysis Results Viewing Well Schematics The Schematic is a tool to display a graphical image of the active wellbore and workstring defined using the case menu. On the Schematic, the workstring components will be defined, and casing shoes will be indicated. By default the well schematic is displayed when you open a case. Riser Casing Open hole section Viewing Survey Plots Several different survey plots are available, regardless of the engineering analysis you are performing. These plots include: • Vertical section • Plan view • Dogleg severity • Inclination • Azimuth • Absolute tortuosity • Relative tortuosity • Build-plane curvature • Walk-plane curvature 62 WELLPLAN Landmark Chapter 2: Basics Printing and Print Preview Printing or preview printing of output is very similar to other software you are probably familiar with. Landmark WELLPLAN 63 Chapter 2: Basics Plot Properties This section describes how to configure, and customize plots. There are seven property tabs containing many different configuration options. You may also customize a line or curve on the plot by moving the cursor over the line, and clicking the right mouse button. When you click the right mouse button on the plot (but not over a line) a list of the associated plots, maximize/minimize options, graph/grid and an option to access plot properties will appear for your selection. You can access plot properties using Edit→Properties or by clicking on the plot, and then selecting the properties button on the plot toolbar. Plot toolbar Properties button The properties dialog contains several tabs to categorize the available options. Changing Curve Line Properties To alter the appearance of a curve on the plot, click the right mouse button when the cursor is on the curve line. Using the menu that appears, you can hide the line, freeze the line, or change the appearance of the line. When you hide a line, it disappears from the plot. Freeze line is a 64 WELLPLAN Landmark Chapter 2: Basics useful feature for sensitivity analysis. When you freeze the line, and then alter some of the analysis data that the plot is based on, the frozen line will be displayed along with the analysis data. Use line properties to change the color, line width and style. Changing the Scale This Scale tab is used to define axis limits. Click this option button to allow the axis range to be calculated based on the limits of the data being displayed. This is the default. Click this option button to specify a fixed number of units per inch (or cm) on the printed page for the X and Y axis. Click this option button to specify range limits. Mark this check box to choose the largest of the two specified (X and Y) scales, and use this scale for both axis. Landmark WELLPLAN 65 Chapter 2: Basics Configuring the Axis Use the Axis tab to define how and where the axis will be displayed. Click this option button to keep the axis lines at the edges of the graph. Changing the Grid Use the General/Grid Tab to define the grid, tick marks, and graph border. Mark this check box to display a grid on the plot. Specify the number of minor tick marks. Specify the spacing of the major tick marks when printing the plot. Mark this check box to include a thin black line around the outside of the plot area. 66 WELLPLAN Landmark Chapter 2: Basics Changing the Axis Labels Use to specify axis labels (text). Type in a label for the X axis and Y axis in their respective fields. Changing the Font Use the Font tab to specify fonts for axis labels, and tick labels. Click on Axis Label button to specify axis label font. Click on Tick Label button to specify tick font. Click on Data Labels button to specify data label font. Landmark WELLPLAN 67 Chapter 2: Basics Changing the Line Styles Use the Line Styles tab to specify color, style and width of lines used for the axis and the grid. You can specify a set Click on ... to display of lines for displaying available colors on the screen and another set for printing. For best results, use Using Data Markers Use the Markers tab to specify the use, size and frequency of data point markers. Mark this check box to turn on data markers or symbols. The default setting is unchecked (no data symbols). Click this option button to specify the frequency of the data markers. You must specify a numeric value to indicate the frequency to place data markers. Mark this check box to assure the last point on the curve always has a marker even if the frequency specified means the point would not have a marker. 68 WELLPLAN Landmark Chapter 2: Basics Configuring the Legend Use the Legend tab to specify whether a legend should be displayed, and to customize legends, including title, font, and location. Mark this check box to display a legend. Specify the number of columns the legend box should use. This is only relevant if several curves are represented in the legend. Use this text box to specify the title displayed in the legend. Click this command button to customize the font used for the legend. Mark this check box to specify that all lines should be shown. Landmark WELLPLAN 69 Chapter 2: Basics DEX and File Importing and Exporting Use File→Data Exchange to access the Data Exchange (DEX) menu. DEX is a way to transfer data between several Landmark products. Several Landmark products are built with the DEX Toolkit (Import, Export, and Browse), such as WELLPLAN, StressCheck, CasingSeat, DrillModel, DFW, COMPASS, and WellCat. Use the DEX Import command (File/Data Exchange/Import) to load pertinent data into your active software product. Once loaded, the data is merged into the software product’s data set. You can then change the data, analyze the data and save it. Using File→Import→Transfer File and File→Export→Transfer File you can transfer data between WELLPLAN 1998.7, 1998.2, and 1998.5 installations. This is different than the DEX transfer. This method deals strictly with transferring data between WELLPLAN versions specified. When you export data, you can export the data for a project, well or a case only. Using File→Import→WELLPLAN 5.3 you can import data from a WELLPLAN 5.3 version of the software. However, you can not import WELLPLAN 6, or WELLPLAN 1998.7 data into a WELLPLAN 5.3 installation. 70 WELLPLAN Landmark Chapter 3 Torque Drag Analysis Torque Drag Analysis can be used to predict and analyze the torque and axial forces generated by drill strings, casing strings, or liners while running in, pulling out, backreaming and/or rotating in a three-dimensional wellbore. The effects of mud properties, wellbore deviation, WOB and other operational parameters can be studied. Overview In this section of the course, you will become familiar with all aspects of using the Torque Drag Analysis module. You will also become familiar with the data presented on reports, and plots. To reinforce what you learn in class, you will complete several exercises designed to prepare you for using the program outside of class. The information presented in this chapter can be used as a study guide during the course, and can also be used as a reference for future torque and drag analysis. At the end of this chapter you will find the methodology used for each analysis mode. The methodology is useful for understanding data requirements, analysis results, as well as the theory used as the basis for the analysis. Supporting calculations and references for additional reading are also included in this chapter. Landmark WELLPLAN 71 Chapter 3: Torque Drag Analysis Torque Drag Analysis: An Introduction The Torque Drag Analysis module can be used to predict the measured weights and torques to expect while tripping in, tripping out, rotating on bottom, rotating off bottom, slide drilling, and backreaming. This information can be used to determine if the well can be drilled, or to evaluate hole conditions while drilling a well. The module can be used for analyzing drillstrings, casing strings, and liners. The Torque Drag Analysis module includes both soft string and stiff string models. The soft string model is based on Dawson’s cable model. In this model, the work string is treated as an extendible cable with zero bending stiffness. Friction is assumed to act in the direction opposing motion. The forces required to buckle the string are determined, and if buckling occurs, the mode of buckling (sinusoidal, transitional, helical, or lockup) is indicated. The stiff string model includes the increased side forces from stiff tubulars in curved hole, as well as the reduced side forces from pipe wall clearance. Starting Torque Drag Analysis There are two ways to begin the Torque Drag module: l Select Torque Drag from the Modules menu, and then select the appropriate analysis mode. l Click the Torque Drag button and then select the appropriate analysis mode from the drop-down list. The contents of the Case and Parameter menu varies depending on the analysis mode you select. 72 WELLPLAN Landmark Choose Torque Drag Analysis from Module menu, or by clicking the Chapter Torque Drag 3: Torque Module Drag Analysis button. Select desired Torque Drag Analysis mode from submenu, or from Mode drop-down list. Available Analysis Modes The Torque Drag Module has four available analysis modes. Each analysis mode will be covered in this course. • Normal Analysis: Calculate the forces, torques, and stresses acting on the work string while the bit is at a particular depth in the wellbore for a number of common drilling load conditions. This analysis calculates surface loads based on bit forces you input. • Calibrate Friction: Calculate the coefficient of friction for cased and open hole sections using actual load data acquired while drilling. The calculated coefficient of friction can be used in another torque and drag analysis. • Drag Chart: Graph the surface torque and measured weight from drilling operations while the bit traverses a range of depths in the wellbore. • Top-Down Analysis: Calculate string forces from loads and torque applied at the surface or at the bottom of the work string. You can also specify if the string is rotating, and reciprocating during tripping operations. (When loads are applied at the bottom of the work string, this analysis is very similar to the Normal Analysis but there is more flexibility over movement and end conditions.) If the surface loads are input, the bit forces are calculated and vice versa. Landmark WELLPLAN 73 Chapter 3: Torque Drag Analysis Using Normal Analysis Purpose and Use Normal Analysis calculates the torque, drag, normal force, axial force, buckling force, neutral point, stress and other parameters for a work string in a three-dimensional wellbore. With a Normal Analysis, all calculations are performed with the bit at one position in the wellbore, and with one set of operational parameters. You may choose to perform the analysis using either the soft or stiff string model. However, for now use the soft string model. Normal Analysis mode calculates the forces acting along the string and at the surface for several operating conditions, including: l Tripping in (with and without rotating) l Tripping out (with and without rotating) l Rotating on bottom l Rotating off bottom l Backreaming l Sliding drilling Based on the API material specifications of pipe class, material, and grade, the following special load cases are also calculated. l Maximum weight on bit to avoid sinusoidal buckling l Maximum weight on bit to avoid helical buckling l Maximum overpull to not exceed yield with the utilization factor while tripping out of hole Entering Case Data All Torque Drag analysis modes use the information input on the Case menu. Depending on the analysis mode selected, additional information may be required to be input using the Case menu. For Normal Analysis, 74 WELLPLAN Landmark Chapter 3: Torque Drag Analysis additional input on the case menu is required using the Torque Drag Setup dialog. For discussion on the Case menu items that are common to all WELLPLAN modules, please refer to the Basics chapter (2) of this manual. The common Case menu options include the General, Offshore, Wellbore Editor, String Editor, Fluid Editor, and Deviation menu. Case Menu options for Normal Analysis mode Selecting Analysis Models and Options The Case→Torque Drag Setup dialog is used to configure the analysis specifications for a torque drag analysis. This dialog is used to specify the use of either the soft or stiff string model in the analysis. Use this dialog to indicate inclusion of sheave friction and other calculation options. The Mechanical Limitations calculations are a convenient means to determine the weight on bit to initiate buckling, or the maximum overpull allowable using a specified percentage of yield. Landmark WELLPLAN 75 Chapter 3: Torque Drag Analysis Check box to include sheave friction in all measured weight calculations. If you want to enable this model, you must also specify the Lines Strung and the Mechanical Efficiency values. Check box to use Bending Stress Magnification corrections. The Stiff String model computes the additional side force from stiff tubulars bending in a curved hole as well as the reduced side forces from pipe straightening due to pipe/hole clearance. Check box to select the viscous fluid torque and drag model. The viscous fluid effects cause differing torque and drag on the string depending on the pipe rotation and trip speeds. The magnitude depends strongly on the fluid rheology model chosen in the fluid editor. Specify the length that you want the contact forces reported. Check boxes for limitations you are interested in. Why Use Bending Stress Magnification Factor? In both tensile and compressive axial load cases, the average curvature between the tool joints is not changed, but the local changes of curvature due to straightening effects of tension or the buckling effects of compression may be many times the average value. Therefore to accurately calculate the bending stress in the pipe body requires the determination of these local maximum curvatures. The quantity bending stress magnification factor (BSMF) is defined as the ratio of the maximum of the absolute value of the curvature in the pipe body divided by the curvature of the hole axis. This factor can be applied as a multiplier on the bending stress calculations to more accurately calculate the bending stress in a work string that has tool joints with outside diameters (OD) greater than the pipe body. This modified bending stress is then used in the calculation of the von Mises stress of the pipe. BSMF is useful because when a drill string with tool joint OD greater than the body OD is subjected to either a tensile or compressive axial load, the maximum curvature of the drillpipe will 76 WELLPLAN Landmark Chapter 3: Torque Drag Analysis exceed that of the hole axis curvature. The drillpipe sections conform to the wellbore curvature primarily through contact at the tool joints. BSMF is applied to the calculated bending stresses when you mark the Use Bending Stress Magnification check box on the Case→Torque Drag Setup dialog. Defining Operating Conditions Use the Mode Data dialog to specify many of the analysis constraints required to perform a Normal Analysis. You may specify which operating mode you want to analyze by checking the appropriate box. The operating modes available include tripping in, tripping out, rotating on bottom, rotating off bottom, sliding, and backreaming. Depending on the operating modes selected, you will be required to specify operating parameters related to that operating mode. The operating parameters may include WOB or Overpull, torque at bit, tripping speed, or rotational speed while tripping. Specify the operating mode you want to analyze by checking the appropriate box or boxes. Trip speed is not used unless a non-zero RPM is entered. Specify the coefficient of friction you want to use. Defining Multiple Fluids The Fluid Columns tabs are used to define the density of the fluids in the annulus and the string. Data entered on these tabs overrides data entered on the Case→Fluid Editor. You can also define a surface pressure to apply to the annulus. If you are not applying pressure at the surface, and you are using one fluid in the string and annulus, enter the fluid information on the Fluid Editor. Landmark WELLPLAN 77 Chapter 3: Torque Drag Analysis Use the Fluid Columns tabs if: l There is more than one fluid in the annulus l There is surface pressure applied to the annulus l The fluid density in the annulus and string are different Tabs for entry of fluid columns in string and annulus. Define a surface pressure to be applied to the annulus. Define a flow rate. This flow rate will be applied to all analysis modes. How does Fluid Flow Change the Forces and Stresses on the Workstring? Fluid flow changes the forces and stresses on the work string in three ways. l The calculated Pump Off Force is an additional compressive force at the end of the string caused by the acceleration of fluid through the bit jets. The calculations for bit impact force are used to determine this force. l Forces and stresses in the drill string are caused by the differential pressure between the pipe and annulus fluid pressures as a result of motor pressure losses. l Fluid and shear forces act on the work string as a result of shear stresses caused by the frictional flow in the pipe and annulus. 78 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Using Friction Reduction Devices Use the Friction Reduction Devices dialog to describe friction reduction devices. You must check the box indicating the use of friction reduction devices, even if you have device(s) entered into the table. You can model both rotating and non-rotating devices. The model assumes that accurate placement of the devices has been determined so that the drillstring does not contact the wellbore in the interval where the friction reduction devices are used. Wellbore to string friction in sections where friction reduction devices are used is relative. For example, assume the wellbore friction (input using Case→Wellbore Editor) is 0.2. If the friction reduction device friction is 0.5, then the friction factor used in the calculations would be 0.2 X 0.5 = 0.1. This approach allows for accurate friction determination when using drag charts and moving the string between cased and open hole sections with different wellbore friction factors. Enter data regarding friction reduction device placement and operating parameters in the table. Each row of the table refers to a single type of friction reduction device placed on consecutive sections of pipe. If more than one type of device is used, define each type on a separate row in the table. Use Frequency columns to specify the number of devices per joint. (A unit is a joint.) Check box if you want to use friction reduction devices. Each row of the table refers to a single type of friction reduction device placed on consecutive sections of pipe. If more than one type of device is used, define each type on a separate row in the table. The unit weight is added to the string weight for analysis purposes. Landmark WELLPLAN 79 Chapter 3: Torque Drag Analysis Analyzing Results Results for a Normal Analysis are presented in tables, plots, and reports. All results are available using the View Menu. In many cases, the same analysis results are presented in more than one form. For example, string tension data can be found in reports, plots, and tables. In general, the plots or tables present the data in a clearer, more concise format than the reports do. Depending on the number of operating modes selected, the reports can get very long and difficult to read unless you print them. Because of time restraints, this course does not discuss every available report, table and plot. If you have specific questions about a plot, table or report, refer to the online help for more detail. View Menu contents for Normal Analysis Plots There are several plots containing analysis results for a normal analysis. These include: • Effective tension • True tension • Torque • Side Force • Fatigue Graph • Stress • Position (only available if using stiff string model) 80 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Effective and True Tension Plot Effective tension plot True tension plot Effective Tension Plot The Effective Tension plot displays the tension in all sections of the work string for the operating modes specified on the Normal Analysis Mode Data dialog as calculated using the buoyancy method. The graph includes data for measured depths from the surface to the string depth specified on the String Editor. The effective tension can be used to determine when buckling may occur. On the plot are curves indicating the loads required to buckle (helical or sinusoidal) the work string. When the effective tension load line for a particular operation mode crosses a buckling load line, the string will begin to buckle in the buckling mode corresponding to the buckling load line. The plot also indicates the tension limit for the work string component at the corresponding measured depth. If the effective tension curve for a particular operating mode exceeds the tension limit curve, the work string is in danger of parting at that point. True Tension Plot The True Tension plot displays the tension in all sections of the work string for the operating modes specified on the Normal Analysis Mode Data Dialog as calculated using the pressure area method. The graph Landmark WELLPLAN 81 Chapter 3: Torque Drag Analysis includes data for measured depths from the surface to the string depth specified on the String Editor. This data should only be used for stress analysis. If you want to determine when a worksting will fail due to tension, refer to the Effective Tension Graph. Torque Graph Component with zero torque limit should be edited using the String Editor to represent the actual component torque limit. Fatigue Plot The View→Fatigue plot presents the bending or buckling stress as a ratio of the fatigue limit. 82 WELLPLAN Landmark Chapter 3: Torque Drag Analysis High level of bending or buckling stresses Landmark WELLPLAN 83 Chapter 3: Torque Drag Analysis Tables Tables are a very useful form of viewing analysis results. Tabular results are organized in a way that makes it easy to quickly find the information you are looking for. Summary Loads Table The View→Table→Summary Loads table contains information pertaining to all sections of the work string. The Summary Loads table is a good place to begin your analysis. This table contains a load summary for the operating modes specified on the Normal Analysis Mode Data dialog. For similar information, view the Summary Report. For each operating mode, the following information is provided: stress mode indicator, buckling mode indicator, torque at rotary table, windup, surface measured weight, total stretch, and neutral point. Stress Column. An S indicates Buckling Column. An H VonMises stress failure, a T indicates indicate helical buckling and an exceeding make-up torque and an F S indicates sinusoidal indicate fatigue. buckling. What are the Loads For a Particular Operating Mode? Use View→Table→Load Data and select a particular operating mode for information for an individual operating mode. For similar information, view the Detail Report. Information presented on the table includes measured depth, component type, distance from bit, internal pressure, external pressure, axial force (pressure area and buoyancy method), drag, torque, twist, stretch, sinusoidal buckling force, helical buckling force, buckling mode flag, and stress mode flag. 84 WELLPLAN Landmark Chapter 3: Torque Drag Analysis What are the Stresses For a Particular Operating Mode? Use View→Table→Stress Data and select a particular operating mode for information for an individual operating mode.This table contains information pertaining to all sections of the work string. Data for each operating mode is specified on a separate table. This table contains information similar to the Stress Graph, including measured depth, component type, distance from bit, hoop stress, radial stress, torsional stress, shear stress, axial stress, buckling stress, bending stress, BSMF, von Mises stress, von Mises stress ratio, and fatigue ratio. Reports Reports are another form of presenting normal analysis results. However, if you will be analyzing more than one operating mode, using plots or tables is an easier way to view the results. Report Options The Report Options dialog is used to specify what additional information will be included on the report. Using this dialog, you can specify to include or exclude much of the information defining the case you are analyzing. Check boxes pertaining to the information you want to include Detailed Report Most of the information presented on the Detailed report is available on tables, or in graphical form on plots. However, the Detailed Report also includes the operating parameters and case data (as specified on the report options dialog) used in the analysis. Plots and tables do not include this information. When you are generating a report for an analysis of several operating modes, the information for each operating mode is separate from all Landmark WELLPLAN 85 Chapter 3: Torque Drag Analysis other operating modes. For example, all tripping in analysis is kept separate from the tripping out analysis. Because there is a lot of data presented on the Detailed Report, it is recommended that reports be limited to analysis of one or two operating modes at a time. Otherwise the reports can get very long and difficult to read. 86 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Calibrating Coefficients of Friction from Field Data Purpose and Use You can calculate the coefficient of friction along the wellbore from actual data collected while drilling. This provides a means of calibrating the model against actual field results. In order to use this analysis mode, you must collect a series of weights and torques at the wellsite. Some of this data is obtained with the string inside the casing shoe, and other information is obtained in the open hole section. When gathering actual field data, it is best if friction reduction devices are not being used. Over the sections where the devices are used, the effects of the friction devices must included in the calibrated friction factors. You must calculate the coefficient of friction in the casing section first, then the open hole. This is required because data recorded in the open hole section includes the combined effects of friction between the string and the casing as well as the friction between the string and the open hole. Therefore, the coefficient of friction for the cased hole must be determined before that of the open hole. The reliability of the data collected is important. Spurious values for any weight may prevent calculating a solution, or may result in an inaccurate solution. It is important that the drillstring is completely inside the casing shoe when you are recording weights for calculating the coefficient of friction inside the casing. It is also important that the string is not reciprocated while recording rotating weights, and vice versa. You may not want to rely on one set of data, but make a decision based on a number of weight readings taken at different depths inside the casing and in the open hole section. It is important to realize that hole conditions may also effect the coefficient of friction calculated. If the actual weights recorded include the effects of a build up of cuttings, the BHA hanging up downhole, or other hole conditions. Because the recorded weights include these effects, the calculated coefficient of friction will also. Landmark WELLPLAN 87 Chapter 3: Torque Drag Analysis Starting the Calibrate Friction Analysis Mode Select Calibrate Friction from Mode drop-down list. Entering Actual Loads Use the Actual Loads dialog to record actual load data encountered at certain depths. This information can be used to calculate coefficients of friction using the Calibrate Friction analysis or it can be displayed in the Drag Chart analysis graphs to compare actual values with calculated values. The actual load data consists of rows or information with one row per measured depth. You can record data for any measured depth. It may be useful to record this information just inside the casing shoe, or at total depth just prior to setting casing. It is not necessary to specify all values for each row. However, the measured depth must always be specified, and must always increase. The trip in, trip out measured weights, and rotating off bottom torque values are required to calibrate the coefficient of friction. Other values are input for plotting actual load data on applicable plots. Required input for calibrating coefficient of friction Calibrating Coefficients of Friction Use the Calibration Data dialog to specify parameters required to calibrate the coefficients of friction. You may calculate the coefficient of friction by two methods: 88 WELLPLAN Landmark Chapter 3: Torque Drag Analysis l Be sure the use actual load check box is not checked, and enter a bit MD. You must also enter at least one of the following: tripping out measured weight, tripping in measured weight, or rotating off bottom torque. The calculated coefficient of friction is based on the selected measured weights and/or torque values you entered for the specified bit MD. l Be sure the Use Actual Load check box is marked, and select an actual load. You can select, deselect, or alter any of the measured weight or torque values recorded for this actual load. The calculated coefficient of friction is based on the selected measured weights and/or torque values. The average coefficient of friction is calculated for the cased, open hole, or combined hole section selected. When selecting from actual loads (entered on actual loads editor), be sure box is checked. View the calculated average coefficient of friction used in analysis. Landmark WELLPLAN 89 Chapter 3: Torque Drag Analysis Using Drag Charts Purpose and Use You can use Drag Chart Analysis to predict the measured weights and torques that will be experienced while operating the work string at a range of depths in the wellbore. The calculations performed for this analysis are similar to those used in the Normal Analysis except the calculations are performed over a range of depths. (A Normal Analysis calculates results for a single bit depth.) As in the Normal Analysis, you may select the operational modes by checking appropriate boxes on the Run Parameters dialog. You can use coefficients of friction that you calculated using Calibrate Friction, the coefficients specified on the Wellbore Editor, or those entered on the Run Parameters dialog. Start Drag Chart Analysis Select Drag Chart from drop-down list. Defining Operating Conditions and Analysis Interval The Run Parameters dialog is used to specify the analysis parameters for a Drag Chart Analysis. On this dialog you indicate the depth interval that you want to analyze. You also select the operational modes you want to analyze, and the forces acting at the bottom of the work string for each of the operational modes. You must also indicate the coefficient of friction that you want to use. Typically the depth range chosen would correspond to the expected run of a given string, or to a complete hole section if the drill string configuration was to remain unchanged throughout the hole section. Keep in mind that the drag chart analysis assumes that only one string, and only one set of operating parameters (fluid, WOB, and so forth) are used through the entire analysis depth range. 90 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Be sure to enter interval to analyze. Use torque point distance to bit to specify where you want to calculate torque magnitude. Displaying Actual Loads Actual loads entered on the Actual Loads dialog can be displayed in the Drag Chart analysis graphs to compare actual values with calculated values. Analyzing Results There are not any reports available for a drag chart analysis. All output is in graphical form. Measured Weight Chart The Measured Weight chart shows measured weights for all operating modes selected on the Run Parameters dialog. This analysis covers only the measured depth interval specified on the run parameters dialog. For the measured weight analysis, a drag chart indicates the tensile and compressive yield limits for each of the string depths analyzed. In the tension analysis, you are able to determine how much overpull you can place on the string before the string will fail. Similarly, for the compression analysis, you can determine how much compressive force Landmark WELLPLAN 91 Chapter 3: Torque Drag Analysis can be applied to the string before the string will yield as a result of buckling. From the graph, you can tell the load that will fail the work string, but you will not be able to determine where the failure occurred. Buckling occurs in sliding and rotating on bottom operating modes at the corresponding bit depths. Minimum measured weight to avoid buckling Torque Point Chart The Torque Point chart displays the maximum torque found at the surface, or at a user specified point in the work string for all rotary operating modes selected on the Run Parameters dialog. The Torque Point chart covers only the measured depth interval specified on the Run Parameters dialog. For reference, the makeup torque limit is displayed on the graph. The torque limit is derated for tension. 92 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Makeup torque as input on Workstring Editor for each component. Landmark WELLPLAN 93 Chapter 3: Torque Drag Analysis Using Top Down Analysis Purpose and Use Top Down Analysis allows the specification of string forces at the surface or bottom hole. You can use this analysis mode to determine downhole forces acting on the work string when you know the surface forces, or you can use this analysis to determine the surface forces when the bit forces are know. Normal analysis also calculates the forces at the surface based on known forces acting at the bit. You may want to use this analysis mode to analyze coiled tubing operations. In the case of coiled tubing, you are driving tubing into the hole with known injector forces at the surface. This analysis mode provides a means of determining the tension or compression forces acting on the tubing downhole. You can specify a tension (positive) or compressive (negative) injector force at the surface. You can also use the Top Down Analysis mode to analyze stuck pipe situations. When a pipe is stuck downhole, you know the forces at the surface, but the downhole loads must be estimated. You may want to know the required surface forces to achieve a specific force to trip a jar. Or you may want to apply a tension or torque at the surface, and from the resulting pipe stretch or twist, you can calculate the stuck point. Selecting Top Down Analysis Select Top Down Analysis from mode drop-down list. Defining Operating Conditions The Mode Data dialog is used to specify the operating parameters for the Top Down analysis. You may specify whether the forces are acting at the top (top down) or at the bottom (bottom up) of the work string. Enter the magnitude of the load and the torque acting on the string. Indicate 94 WELLPLAN Landmark Chapter 3: Torque Drag Analysis axial or rotational string movement on the dialog. If you specify speed, you don’t have to specify RPM and vice versa. Weight on bit input is assumed to be compressive, so do not enter a negative number. Specify the friction factor you want to use. Analyzing Results There are several plots, tables, and one report available for reviewing results. Many of the available output are similar to the output for the normal analysis. Tables The two tables available for the top down analysis are the load data table and the stress data table. Load Data Table The Load Data table contains information pertaining to all sections of the work string for the load conditions specified on the top down analysis mode data dialog. The table includes data for measured depths from the surface to the string depth specified on the string editor. For similar information, view the detail report or the stress graph. The data presented on the table includes measured depth, component type, distance from bit, internal pressure, external pressure, axial force – pressure area method, axial force – buoyancy method, drag, torque, Landmark WELLPLAN 95 Chapter 3: Torque Drag Analysis twist, stretch, sinusoidal buckling force, helical buckling force, buckling mode flag, and the stress mode flag. Stress Data Table The Stress Data table contains information pertaining to all sections of the work string for the load conditions specified on the top down analysis mode data dialog. The graph includes data for measured depths from the surface to the string depth specified on the string editor. This is a table form output of the data presented graphically on the Single Stress graph, or on the Detailed Report. The table includes the following information: measured depth, component type, distance from bit, hoop stress, radial stress, torsional stress, shear stress, axial stress, buckling stress, bending stress, BSMF, Von Mises stress, Von Mises stress ratio, and fatigue ratio. Reports Report Options The same report options that are available for other torque drag analysis modes are also available with the Top Down Analysis. The report 96 WELLPLAN Landmark Chapter 3: Torque Drag Analysis options control the content of the report to some degree. Several sections of the report can be eliminated or included based on selections made using the report options. If you are concerned about report length, using the Report Options dialog is a means to shorten the report. Detail Report The Detail Report displays well information, operating parameters, loads and forces acting on the string, as well as additional information, but only for the operating load specified on the Top Down Analysis Mode Data dialog. For the specified operating load, the Detail report displays: torque at the rotary table, total string windup with and without bit torque, measured weight, total stretch of the string, the distance from the bit and from the surface to the neutral point, the distance from the bit and from the surface to the point where the axial stress is zero, buckling mode indicators, stress limit indicators, internal work string pressure, external work string pressure, and contact force. Much of this information is displayed in the various graphs or in the Load Data table. Plots There are several plots available for a Top Down analysis. The following is a window containing the Stress Plot in one pane and the Position Plot in the other pane. The stress plot indicates the stresses in all sections of the work string based on the load information specified on the Top Down analysis mode data dialog. The graph includes data for measured depths from the surface to the string depth specified on the string editor. For similar information, view the Stress Data Table or the Detail Report. Stresses included on the graph include hoop, radial, torsion, shear, axial, buckling, bending, Von Mises stress, and the stress limit. All stresses are calculated, except for the stress limit which is the pipe yield stress specified on the string editor. The Position Plot indicates the position of the work string in the wellbore for the operating loads specified on the Top Down Analysis Mode Data dialog. The graph includes data for measured depths from the surface to the string depth specified on the string editor. Use this graph to determine where the pipe lies in the wellbore. The Position Plot is really only useful when using the stiff string model. Since the soft string model assumes the string is lying along the center of the wellbore, the Position Plot offers no usable information for soft string analysis. Landmark WELLPLAN 97 Chapter 3: Torque Drag Analysis Stress limit is input on the Position of string in center of String Editor. wellbore 98 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Using Stiff String Analysis Purpose WELLPLAN Torque Drag analysis contains two calculation models. As discussed earlier, the soft string model assumes the string lies along the center of the wellbore. The soft string model is based on Dawson’s soft string model. The stiff string model uses a finite element analysis approach to determine the downhole forces acting on the string. The stiff string model is more computation intensive, and will take more time to calculate the results than the soft string model does. Depending on the speed of your computer, the calculation time difference may be significant. The stiff string model accounts for the following: tubular stiffness in bending, tubular joint to hole wall clearance, stiffness modified for compressive force, single point weight concentrations. The stiff string analysis impacts the analysis torque drag results for side force, torque, drag, bending stress, and string position in the wellbore. When to Use the Stiff String Model In general, stiff string analysis should be used in the following situations: • To evaluate stiff tubulars run in a well with a build rate of 15 deg/100ft or more • To analyze running stiff casing in a well • To observe buckling using the Position Plot • To analyze a work string containing upsets found on stabilizers or friction reduction devices Activating Stiff String Model The Stiff String Analysis is activated by checking the Stiff String box on the Torque Drag Setup Data dialog. Landmark WELLPLAN 99 Chapter 3: Torque Drag Analysis Check box to use stiff string analysis. Analyzing Results Plots High position indicates the pipe position relative to the highside or low side (-ve) of the hole (that is, when toolface is 0-180 degrees). Normally in a straight inclined hole, with pipe in tension, the pipe will be on the low side of the hole due to gravity. At the kick off point of a build the pipe will be on the high side of the hole due to tension. Helically buckled pipe will zig-zag between high side and low side. Right position indicates the pipe position relative to the left (-ve) or right (+ve) of the hole (i.e. toolface 90-270). Normally in a straight inclined hole the pipe lies in the middle. Only when there is azimuth turn or sinusoidal buckling does the pipe move left or right of the center. In sinusoidal buckling the pipe snakes left and right of the center but does not reach the clearance limit. The clearance limit is only reached in helical buckling. Clearance limit = 0.5 " (Hole Inside diameter - Pipe Tool Joint Diameter). This is the maximum radial movement of the pipe in any direction. None of the position lines should exceed this red line. The pipe body diameter is not considered because it rarely influences movement. Only in 3 1/2" pipe or smaller does the pipe body touch the hole wall due to both weight and buckling. 100 WELLPLAN Landmark Chapter 3: Torque Drag Analysis String is not in the center of the wellbore using stiff string analysis. Separate curve for each stress type Clearance limit based on Wellbore Editor information. Landmark WELLPLAN 101 Chapter 3: Torque Drag Analysis Analysis Mode Methodology Each of the next four sections covers one of the analysis modes available in the Torque Drag module. In each section, the major analysis steps for the analysis mode are discussed. Within the analysis steps there may be a reference to a calculation. The name of the calculations are presented in italic for recognition. Many calculations apply to more than one analysis mode. To avoid duplicating information, the calculations are presented alphabetically in the section titled Supporting Information and Calculations. If you require more information about a particular calculation, please refer to “Supporting Information and Calculations” on page 110. Normal Analysis In a Normal Analysis the calculations are performed for a work string, in a three-dimensional wellbore, at one bit depth, and with one set of operational parameters. If any of these items change (different bit depth, different work string, different mud weight, and so forth) then the Normal Analysis must be re-run. A Normal Analysis can investigate six load cases or operating conditions. These six load cases consist of tripping out, tripping in, rotating on bottom, rotating off bottom, sliding, and backreaming. During the analysis the following steps are performed. 1. The first step is to initialize all load cases with the loads at the bit, including torques and axial force. These parameters are input on the Normal Analysis Mode Data dialog. For a Normal Analysis, the loads at the bit must be input, so the surface loads can be calculated. 2. For both soft and stiff string models, the work string is broken into segments (elements) with a length equal to either a minimum of 30 feet or to the component length. This defines the segment to be analyzed. After the analysis of a segment is complete, the segment above is analyzed. This procedure is repeated until the entire string has been analyzed. For each segment, the following steps are performed: a) Interpolate the survey data at start and end of segment using the surveys entered in the Survey Editor (on the Case menu). Calculate the build rate, turn rate and dogleg severity. The 102 WELLPLAN Landmark Chapter 3: Torque Drag Analysis minimum curvature method is used for all survey calculations. If the surveys had tortuosity applied, the “tortured” surveys are used. b) Determine the wellbore at this depth, and modify the tubular wall thickness based on the Pipe Wall Thickness Modification Due to Pipe Class calculations (page 126). c) Compute the weight per foot of the segment in fluid and at the wellbore angle using the Buoyed Weight calculations (page 114). Because the work string is lying in a wellbore surrounded by fluids, there are resultant hydrostatic pressures acting on all interior and exterior surfaces of the pipe. The Buoyed Weight calculations determine the resultant weight of the segment considering the hydrostatic pressures acting on it. d) Determine the force required to buckle the segment in the wellbore using the Critical Buckling Force calculations (page 116). The critical buckling force is the axial force required to be exerted on a work string to initiate buckling. Buckling first occurs when compressive axial forces exceed a critical buckling force. The axial force computed using the Buoyancy Method (Axial Force calculations, page 111) is used to compare with the critical buckling force to determine the onset of buckling. This is because the critical buckling force calculations are based on the same assumptions regarding hydrostatic pressure. e) Calculate the normal (side) force using the Side Force calculations for the Soft String Model (page 128), or for the Stiff String Model (page 130). The side force or normal force is a measurement of the force exerted by the wellbore onto the work string. f) Calculate the drag acting on the segment using the Drag Force calculations (page 119). The magnitude of the drag force is influenced by the selection of Friction Factor. g) Determine the axial forces acting on the segment using the Axial Force calculations (page 111). Axial forces act along the axis of the work string. h) If buckling occurs, determine the additional side force due to buckling by using the Additional Side Force calculations (page 110). Landmark WELLPLAN 103 Chapter 3: Torque Drag Analysis i) Calculate string torque using the Torque calculations (page 137). Any input bit torque will be added to calculated torque. j) Determine stresses using the Stress calculations (page 132). k) Perform Fatigue calculations (page 121). l) Perform Twist calculations (page 139) and Stretch calculations (page 135). 3. Apply Sheave Friction Correction calculations (page 127) to tension at the surface. This correction is only made if specified on the Torque Drag Setup dialog. 4. Compute pick up and slack off for tripping load cases. 5. Calculate maximum weight on bit to buckle (sinusoidal and helical) the work string, and maximum allowable overpull. Calibrate Friction Analysis Calibrate Friction Analysis calculates the coefficient of friction along the wellbore using actual (field) data collected while drilling. This provides a means of calibrating the program model against actual field results. The following are an overview of the calculations performed. 1. The work string is broken into the minimum of 30 feet, or the component length. This is the segment to be analyzed. After the analysis of a segment is complete, the segment above it will be analyzed. This procedure is repeated until the entire string has been analyzed. a) Interpolate survey at start and end of segment. Calculate build rate, turn rates and dogleg severity. The minimum curvature method is used for all survey calculations. If the surveys had Tortuosity (page 137) applied, the “tortured” surveys are used. b) Determine the wellbore at this depth, and apply Pipe Wall Thickness Modification Due to Pipe Class calculations (page 126). c) Compute the weight per foot of the segment in fluid and at the wellbore angle using the Buoyed Weight calculations (page 114). Because the work string is lying in a wellbore surrounded by fluids, there are resultant hydrostatic pressures acting on all 104 WELLPLAN Landmark Chapter 3: Torque Drag Analysis interior and exterior surfaces of the pipe. The Buoyed Weight calculations determine the resultant weight of the segment considering the hydrostatic pressures acting on it. d) Estimate the coefficient of friction for either the cased hole, or the open hole, or both. For each of the load cases, the following steps (1 through 5) are performed until the calculated torque and hookloads match the input or field values. If the values don’t match, another coefficient of friction is estimated, and the following steps are performed again. 1. Calculate the normal (side) force using the Side Forcepage 128 calculations for the soft string model or for the stiff string model. The side force or normal force is a measurement of the force exerted by the wellbore onto the work string. 2. Calculate the drag acting on the segment using the Drag Force calculations (page 119). The magnitude of the drag force is influenced by the selection of the Friction Factor. 3. Determine the axial forces acting on the segment using the Axial Force calculations (page 111). Axial forces act along the axis of the work string. 4. Calculate string torque using the Torque calculations (page 137). 5. Apply Sheave Friction Correction calculations (page 127) to tension at the surface. This correction is only made if specified on the Torque Drag Setup dialog. Drag Chart Analysis Drag Chart Analysis performs essentially the same analysis steps as performed in the Normal Analysis. However, in a Drag Chart analysis, you can specify a range of bit depths. (A Normal Analysis is performed at a single bit depth.) For each bit depth in the Drag Chart Analysis, the largest torque or measured weight occurring anywhere in the work string is recorded. This information is then available in graphical output. The following is a brief overview of the calculations. Landmark WELLPLAN 105 Chapter 3: Torque Drag Analysis 1. Begin with the first bit depth. The first step is to initialize all load cases with the loads at the bit, including torques and axial force. These parameters are input on the Run Parameters Data dialog. 2. Next, the work string is broken into the minimum of 30 feet, or the component length. This is the segment that will be analyzed. After the analysis of a segment is complete, the segment above it will be analyzed. This procedure is repeated until the entire string has been analyzed. a) Interpolate survey at start and end of segment. Calculate build, turn rates, and dogleg severity. The minimum curvature method is used for all survey calculations. If the surveys had tortuosity applied, the “tortured” surveys are used. b) Determine the wellbore at this depth, and apply Pipe Wall Thickness Modification Due to Pipe Class calculations (page 126). c) Compute the weight per foot of the segment in fluid and at the wellbore angle using the Buoyed Weight calculations (page 114). Because the work string is lying in a wellbore surrounded by fluids, there are resultant hydrostatic pressures acting on all interior and exterior surfaces of the pipe. The Buoyed Weight calculations determine the resultant weight of the segment considering the hydrostatic pressures acting on it. d) Determine the force required to buckle the segment in the wellbore using the Critical Buckling Force calculations (page 116). The critical buckling force is the axial force required to be exerted on a work string to initiate buckling. Buckling first occurs when compressive axial forces exceed a critical buckling force. The axial force computed using the Buoyancy Method is used to compare with the critical buckling force to determine the onset of buckling. This is because the Critical Buckling Force calculations are based on the same assumptions regarding hydrostatic pressure. e) Calculate the normal (side) force using the Side Force calculations for the Soft String Model (page 128), or for the Stiff String Model (page 130). The side force or normal force is a measurement of the force exerted by the wellbore onto the work string. 106 WELLPLAN Landmark Chapter 3: Torque Drag Analysis f) Calculate the drag acting on the segment using the Drag Force calculations (page 119). The magnitude of the drag force is governed by the selection of Friction Factor (page 125). g) Determine the axial forces acting on the segment using the Axial Force calculations (page 111). Axial forces act along the axis of the work string. h) If buckling occurs, determine the additional side force due to buckling by using the Additional Side Force calculations (page 110). i) Calculate string torque using the Torque calculations (page 137). 3. Apply Sheave Friction Correction calculations (page 127) to tension at the surface. This correction is only made if specified on the Torque Drag Setup dialog. 4. Determine the measured weight at the surface, and the maximum torque at any point in the work string with the bit at the specified depth. Repeat the calculations with the next bit depth. Top Down Analysis Top Down Analysis allows the specification of string forces from the surface. You can use this mode to determine downhole forces acting on the work string when you know the surface forces. This analysis mode is in many ways the opposite of the Normal Analysis. A Normal Analysis calculates the forces at the surface based on known forces acting at the bit. You may want to use this analysis mode to analyze coiled tubing operations. In the case of coiled tubing, you are driving tubing into the hole with known injector forces at the surface. This analysis mode provides a means of determining the tension or compression forces acting on the tubing downhole. You can specify a tension (positive) or compressive (negative) injector force at the surface. You can also use this analysis mode to analyze stuck pipe situations. When a pipe is stuck downhole, you know the forces at the surface, but the downhole loads must be estimated. You may want to know the required surface forces to achieve a specific force to trip a jar. You may want to apply a tension or torque at the surface, and from the resulting pipe stretch or twist, you can calculate the stuck point. Landmark WELLPLAN 107 Chapter 3: Torque Drag Analysis 1. The first step is to initialize with the loads at the surface, including torques and axial force. These parameter are input on the Top Down Analysis Mode Data dialog. 2. Next, the work string is broken into the minimum of 30 feet, or the component length. This is the segment that will be analyzed. After the analysis of a segment is complete, the segment below it will be analyzed. This procedure is repeated until the entire string has been analyzed (from the surface down the string). a) Interpolate survey at start and end of segment. Calculate build and turn rates, and the dogleg severity. The minimum curvature method is used for all survey calculations. If the surveys had tortuosity applied, the “tortured” surveys are used. b) Determine the wellbore at this depth, and apply Pipe Wall Thickness Modification Due to Pipe Class calculations (page 126). c) Compute the weight per foot of the segment in fluid and at the wellbore angle using the Buoyed Weight calculations (page 114). Because the work string is lying in a wellbore surrounded by fluids, there are resultant hydrostatic pressures acting on all interior and exterior surfaces of the pipe. The Buoyed Weight calculations determine the resultant weight of the segment considering the hydrostatic pressures acting on it. d) Determine the force required to buckle the segment in the wellbore using the Critical Buckling Force calculations (page 116). The critical buckling force is the axial force required to be exerted on a work string to initiate buckling. Buckling first occurs when compressive axial forces exceed a critical buckling force. The axial force computed using the Buoyancy Method is used to compare with the critical buckling force to determine the onset of buckling. This is because the critical buckling force calculations are based on the same assumptions regarding hydrostatic pressure. e) Calculate the normal (side) force using the Side Force calculations for the Soft String Model (page 128), or for the Stiff String Model (page 130). The side force or normal force is a measurement of the force exerted by the wellbore onto the work string. 108 WELLPLAN Landmark Chapter 3: Torque Drag Analysis f) Calculate the drag acting on the segment using the Drag Force calculations (page 119). The magnitude of the drag force is governed by the selection of Friction Factor (page 125). g) Determine the axial forces acting on the segment using the Axial Force calculations (page 111). Axial forces act along the axis of the work string. h) If buckling occurs, determine the additional side force due to buckling by using the Additional Side Force calculations (page 110). i) Calculate string torque using the Torque calculations (page 137). Any input bit torque will be added to the calculated torque. j) Determine stresses using the Stress calculations (page 132). k) Perform Fatigue calculations (page 121). l) Perform Twist calculations (page 139) and Stretch calculations (page 135). 3. Apply Sheave Friction Correction calculations (page 127) to tension at the surface. This correction is only made if specified on the Torque Drag Setup dialog. 4. Compute the pick up and slack off. 5. Calculate maximum weight on bit required to buckle (sinusoidal and helical) the work string, and maximum allowable overpull. Landmark WELLPLAN 109 Chapter 3: Torque Drag Analysis Supporting Information and Calculations The calculations and information in this section are presented in alphabetical order using the calculation or topic name. The material contained in this section is intended to provide you more detailed information and calculations pertaining to many of the steps presented during the descriptions of the analysis mode methodologies. If the information in this section does not provide you the detail you require, please refer to “References” on page 143 for additional sources of information pertaining to the topic you are interested in. Additional Side Force Due to Buckling Once buckling has occurred, there is an additional side force due to increased contact between the wellbore and the work string. For the soft string model, the following calculations are used to compute the additional side force. These calculations are not included in a stiff string analysis because the stiff string model considers the additional force due to buckling in the derivation of the side force. Sinusoidal Buckling Mode No additional side force due to buckling is added. Helical Buckling Mode 2 rFaxial Fadd = 4 EI 110 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Where: Fadd = Additional side force Faxial = Axial compression force calculated using the buoyancy method E = Young’s modulus of elasticity I = Moment of Inertia r = Radial clearance between wellbore and work string Axial Force There are two calculation methods to determine the axial force: the buoyancy method and the pressure area method. In checking for the onset of buckling, the buoyancy method is used. This is because the Critical Buckling Force calculations (page 116) are based on the same assumptions regarding hydrostatic pressure. For stress calculations, the pressure area method is used. Both methods predict the same measured weight at the surface because there is no hydrostatic force acting at the surface. Below the surface, the axial force calculated using each method will be different. Consider a work string “hanging in air,” or more specifically, in a vacuum. Some of the string weight is supported at the bottom by a force (specifically, the weight on bit). In this situation, the upper portion of the string is in axial tension, and the lower portion of the string is in axial compression. Somewhere along the string there is a point where the axial force changes from tension to compression, and the axial stress is zero. This is the neutral point. In this simple case, the distance from the bottom of the string up to the neutral point can be calculated by dividing the supporting force at the bottom (specifically, the weight on bit) by the weight of the string per unit length. In other words, the weight of the string below the neutral point is equal to the supporting force. In a normal drilling environment, the string is submerged in a fluid. The fluid creates hydrostatic pressure acting on the string. Two different neutral points can be calculated as a result of the handling of the hydrostatic forces. The buoyancy method includes the effects of buoyancy, while the pressure area method does not. Landmark WELLPLAN 111 Chapter 3: Torque Drag Analysis The pressure area method computes the axial forces in the work string by calculating all the forces acting on the work string, and solving for the neutral point using the principle of equilibrium. Using this method, the axial force and axial stress is exactly zero at the neutral point. Using the buoyancy method, the axial force at the neutral point is not zero. The axial force and stress is equal to the hydrostatic pressure at the depth of the neutral point. Because hydrostatic pressure alone will never cause a pipe to buckle, the buoyancy method is used to determine if and when buckling occurs. Buoyancy Method The buoyancy method is used to determine if buckling occurs. [ ] Faxial = ∑ LWair Cos (Inc ) + Fdrag + ∆Farea − Fbottom − WWOB + FBS Pressure Area Method The pressure area method is used to calculated stress. [ ] Faxial = ∑ LWair Cos (Inc ) + Fdrag + ∆Farea − Fbottom − WWOB 112 WELLPLAN Landmark Chapter 3: Torque Drag Analysis L = Length of drillstring hanging below point (ft) W air = W eight per foot of the drillstring in air (lb/ft) Inc = Inclination (deg) Fbottom = Bottom pressure force, a compression force due to fluid pressure applied over the cross sectional area of the bottom component Farea = Change in force due to a change in area at junction between two components of different cross sectional areas, such as the junction between drill pipe and heavy weight or heavy weight and drill collars. If the area of the bottom component is larger the force is a tension, if the top component is larger the force is compression. WWOB = W eight on bit (lb) (0 for tripping in & out) Fdrag = Drag force (lb) FBS = Buckling Stability Force = PressExternal*AreaExternal – PressInternal*AreaInternal Pipe: Area External = π/4*(0.95*BOD*BOD + 0.05*JOD*JOD) AreaInternal = π/4*(0.95*BID*BID + 0.05*JID*JID) Collar: AreaExternal = π/4*(BOD*BOD) AreaInternal = π/4*(BID*BID) PressExternal = AnnulusSurfacePress + Σ (AnnulusPressGrad * TVD) PressInternal = StringSurfacePress + Σ (StringPressGrad * TVD) Bending Stress Magnification (BSM) Bending stress magnification (BSM) will be applied to the calculated bending stresses if you have checked the BSM box on the Torque Drag Setup Data dialog. The magnitude of the BSM is reported in the stress data table of the Normal Analysis Detail Report, and in the Top Down Analysis Detail Report. Landmark WELLPLAN 113 Chapter 3: Torque Drag Analysis When a drill string is subjected to either tensile or compressive axial loads, the maximum curvature of the drillpipe body exceeds that of the hole axis curvature. The drillpipe sections conform to the wellbore curvature primarily through contact at the tool joints. In both tensile and compressive axial load cases the average curvature between the tool joints is not changed, but the local changes of curvature due to straightening effects of tension or the buckling effects of compression may be many times the average value. Therefore, to accurately calculate the bending stress in the pipe body requires the determination of these local maximum curvatures. The bending stress magnification factor (BSM) is defined as the ratio of the maximum of the absolute value of the curvature in the drillpipe body divided by the curvature of the hole axis. The BSM is applied as a multiplier on the bending stress calculation. This modified bending stress is then used in the calculation of the von Mises stress of the drillpipe. Buoyed Weight The surface pressure and mud densities input on the Fluids Column tabs, or the mud weight input on the Fluid Editor are used to determine the pressure inside and outside of the work string. Using the equations listed below, these pressures are used to determine the buoyed weight of the work string. The buoyed weight is then used to determine the forces and stresses acting on the work string in the analysis. 114 WELLPLAN Landmark Chapter 3: Torque Drag Analysis WBuoy = WAir − WFluid WFluid = (MWAnnular ∗ AExternal) − (MWInternal ∗ AInternal ) For components with tool joints = π 4 ∗ [0.95 ∗ (OD Body ) + 0.05 ∗ (OD Jo int )2 ] 2 A External A Internal = π 4 ∗ [ 0 .95 ∗ (ID Body ) + 0 . 05 ∗ (ID Jo int )2 ] 2 Note: The constants 0.95 and 0.5 are used to assume that 95% of the component length is pipe body, and 5% is tool joint. For components without tool joints A Internal = π 4 ∗ (ID Body )2 AExternal = π 4 ∗ (OD Body ) 2 Where: OD Body = Outside diameter of component body OD Jo int = Outside diameter of tool joint ID Body = Inside diameter of component body ID Jo int = Inside diameter of tool joint AExternal = External area of the component AInternal = Internal area of the component WFluid = Weight per foot of displaced fluid W Buoy = Buoyed weight per foot of component MW Annular = Annular mud weight at component depth in the wellbore MWInternal = Internal mud weight at component depth inside the component Landmark WELLPLAN 115 Chapter 3: Torque Drag Analysis Critical Buckling Forces The critical buckling force is the axial force required to be exerted on a work string to initiate buckling. Buckling first occurs when compressive axial forces exceed a critical buckling force. The axial force computed using the Buoyancy Method is used to compare with the critical buckling force to determine the onset of buckling. This is because the critical buckling force calculations are based on the same assumptions regarding hydrostatic pressure. The critical buckling forces can be found listed by component type and measured depth in the sinusoidal buckling and helical buckling columns of the Normal Analysis Detail Report or the Top Down Analysis Detail Report. The values in these two columns can be compared to the Drill String Axial Force - Buoyancy column to determine if the component is bucked at that depth. If the compressive force indicated in the Buoyancy column exceeds that of either the sinusoidal buckling or helical buckling column, the component is buckled. If buckling occurs, an S indicating sinusoidal buckling, an H indicating helical buckling, or an L indicating lockup will be listed in the B column. Different critical buckling forces are required to initiate the sinusoidal and helical buckling phases. Calculations for the critical buckling force also vary depending on the analysis options selected on the Torque Drag Setup Data dialog. Straight Model Calculations The Straight Model was the model used in WELLPLAN 5.3 Torque Drag analysis. This model divides the work string into 30 foot sections. The inclination and azimuth of these sections change along the well as described by the survey data and the approximate 3D well shape. However, each 30 foot section is assumed to be “straight” or of constant inclination. By contrast, the curvilinear model takes into account the inclination (build or drop) change within each 30 foot section. 116 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Critical Inclination to Select Buckling Model [ Θ c = Sin −1 (1 . 94 2 ) ∗ r ∗ (W EI ) 2 13 ] If (Inc > Θ C ) , then: F S = 2[Sin (Inc )EIW / r ] 12 If (Inc < Θ C ) , then: ( F S = 1 .94 EIW ) 2 13 Curvilinear Model For a torque drag analysis, the work string is divided into 30 foot sections. The straight model assumes each section is of constant inclination. The curvilinear model takes into account the inclination (build or drop) change within each 30 foot section. In hole sections where there is an angle change, compression in the pipe through the doglegs causes extra side force. The additional side force acts to stabilize the pipe against buckling. An exception is when the pipe is dropping angle. In a build section of the well: 2 EI κ EI κ EIW Sin (Inc ) 2 FS = +2 + r r r In a drop section of the well: rW Sin (Inc ) κ test = EI if (κ ≥ κ test ) then, 2 EI κ EI κ EIW Sin ( Inc ) 2 FS = −2 − r r r if (κ < κ test ) then, 2 EI κ EI κ EIW Sin (Inc ) 2 FS = − +2 + r r r Landmark WELLPLAN 117 Chapter 3: Torque Drag Analysis Loading and Unloading Models In SPE 36761, Mitchell derives the loading method. The idea presented is that for compressive axial loads between 1.4 and 2.8 times the sinusoidal buckling force, there is enough strain energy in the pipe to sustain helical buckling, but not enough energy to spontaneously change from sinusoidal buckling to helical buckling. If you could reach in and lift the pipe up into a helix, it would stay in the helix when you let go. In an ideal situation without external disturbances the pipe would stay in a sinusoidal buckling mode until the axial force reached 2.8 times the sinusoidal buckling force. At this point, the pipe would transition to the helical buckling mode. This is the “loading” scenario. Once the pipe is in the helical buckling mode, the axial force can be reduced to 1.4 times the sinusoidal buckling force, and the helical mode will be maintained. If the axial force falls below 1.4 times the sinusoidal buckling force, the pipe will fall out of the helix into a sinusoidal buckling mode. This is the “unloading” scenario. In the figure above, in stage 1 the compressive load is increased from the force required for sinusoidal buckling to the threshold force where the pipe snaps into a helically buckled state. This is the “loading” force. Stages 2 and 3 represent the reduction of the compressive load to another threshold force to snap out from helically buckled into a sinusoidal buckled state. This is the “unloading” force. Taking friction into consideration, we can imagine buckling friction acts a bit like glue. It gives resistance when the pipe is pushed into buckling (loading) and it also provides resistance to release the pipe from buckling (unloading). But when the pipe is rotating the “glue” bond is broken, and gives no resistance. Where friction is effective, the transitions from sinusoidal to helical and vice versa are more explosive because the pipe picks up more spring energy because the friction 118 WELLPLAN Landmark Chapter 3: Torque Drag Analysis prevents free pipe movement until the stored energy is enough to break the friction bond. Loading Model FH = 2.828427 FS Unloading Model FH = 1.414FS Where: FS = C om pression force to induce onset of sinusoidal buckling FH = C om pression force to induce onset of helical buckling I = M om ent of inertial for com ponent E = Y oung’s m odulus of elasticity W = T ubular weight in m ud Inc = W ellbore inclination r = R adial clearance between wellbore and com ponent κ = C urv ature in the v ertical plane (build or drop) Drag Force Calculations The drag force acts opposite to the direction of motion. The direction of the drag force is governed by the type of analysis being performed. The drag force may be acting up the axis of the pipe, down the axis of the pipe, or acting in a tangential direction resisting the rotation of the pipe. The drag force is calculated using the following equation. T FD = FN ∗ µ ∗ V Where: Landmark WELLPLAN 119 Chapter 3: Torque Drag Analysis T = Trip speed RPM A = Angular speed = diameter ∗ π ∗ 60 V = Resultant speed = (T 2 + A2 ) FN = Side or norm al force µ = Coefficient of friction (friction factor) FD = Drag force The side force or normal force is a measurement of the force exerted by the wellbore onto the work string. In the diagram below, the forces acting on a small segment of work string lying in an inclined hole are shown. In this simple diagram, the segment is not moving. From this diagram we can see that the normal force acts in a direction perpendicular to the inclined surface. The weight of the work string acts downward in the direction of gravity. Another force, the drag force, is also acting on the segment. The drag force always acts in the opposite direction of motion. The segment does not slide down the inclined plane because of the drag force. The magnitude of the drag force depends on the normal force, and the coefficient of friction between the inclined plane and the segment. The coefficient of friction is a means to define the friction between the wellbore wall and the work string. 120 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Where: FN = Normal Force FD = Drag Force W = Weight of segment Fatigue Calculations WELLPLAN torque drag includes fatigue analysis because it is a primary cause of drilling tubular failure. A fatigue failure is caused by cyclic bending stresses when the pipe is run in holes with doglegs. The source of fatigue failure is micro fractures between the crystal structures of the material caused in the construction of the material. These cracks are widened by successive stress reversals (tensile/compressive) in the body of the cylinder. The following five steps are applied in the Torque/Drag analysis of fatigue loading and prediction. Cyclic stresses are those components of stress that change and reverse every time the pipe is rotated. In Torque Drag, only bending and buckling stresses go through this reversal. In the stiff string model the buckling stresses are integrated with the pipe curvature and hence included in bending; the soft string model treats buckling stress independent to bending stress and adds the two together for fatigue analysis. Bending stresses are caused by pipe running through a curved hole. On one side of the pipe is bent into tension and the other side of the pipe is bent into compression (see diagram following). Bending stresses are a maximum at the outside of the pipe body and undergo a simple harmonic motion as the pipe rotates. Landmark WELLPLAN 121 Chapter 3: Torque Drag Analysis Apply Bending Stress Magnification Factor calculations (page 113). Bending stress concentrates close to the tool joints in externally upset pipe when the pipe is in tension. This magnifies the bending radius in the section of pipe close to the tool joints. Establish A Fatigue Endurance Limit For The Pipe Fatigue endurance limit is not a constant value that is related to the yield strength of the pipe. It cannot be associated with the material grade of the pipe. There are also bending stress concentrations in the tubular due to the design of tool-joints and the shape of upsets in the body of the pipe apart from those considered in the bending stress magnification factor. Drillpipe 25-35 Kpsi This is a general value for continuous tubular steel. Heavy 18-25 Kpsi More stress concentration in tool Weight joint Drill Collars 12-15 Kpsi Includes drill collars and other non upset BHA components, like jars, stabilizers, MWD, and so forth. Casings 5-20 Kpsi Depends on connectors: 5 for 8 round, 20 for premium Non externally upset tubulars like collars and casing will have maximum concentration of bending stress at the tool joint. 122 WELLPLAN Landmark Chapter 3: Torque Drag Analysis The fatigue endurance limit needs to be reduced if the steel is used in a corrosive environment like saline (high chloride) or hydrogen sulfide environment. Derate The Fatigue Endurance Limit For Tension The crack widening mechanism that causes fatigue is strongly influenced by tension in the pipe. A simple empirical mechanism is used to reduce the fatigue endurance limit for tensile stress as a ratio of the tensile yield stress. This is known as the Goodman relation. F AY = σ MY AE If F AB > 0.0 then, F σ FL = σ FEL 1 − AB (Tension) FAY Else, σ FL = σ FEL (Compression) R F = (σ BEND + σ BUCK )σ FL AINTC = π 4 ( ID B 2 ) AE = AEXT − AINT AEXTP = π 4 (0.95OD B 2 + 0.05OD J 2 ) AINTP = π 4 (0.95 ID B 2 + 0.05 ID J 2 ) AEXTC = π 4 (OD ) B 2 AINTC = π 4 (ID ) B 2 Landmark WELLPLAN 123 Chapter 3: Torque Drag Analysis Where: F AY = Axial force required to generate the yield stress, (lb) F AB = Axial force (Buoyancy M ethod), (lb) σ FL = Fatigue lim it, (psi) σ MY = M inim um yield stress specified by G rade , (psi) σ FEL = Fatigue endurance lim it, (psi) (For pipe and heav y weight, this is input. All other com ponents assum e = 35,000 psi σ BEND = Bending stress, (psi) (Corrected by BSM F) σ BUCK = Buckling stress, (psi) (only if buckling occurs) RF = Fatigue Ratio AE = Effectiv e sectional area, in ( ) 2 A EXT ( ) = External area of pipe, heav y weight or collar com ponent, in 2 = Internal area of pipe, heav y weight, or collar com ponent, (in ) 2 A INT = Pipe and heav y weight external area, (in ) 2 A EXTP = Pipe and heav y weight internal area, (in ) 2 A INTP = Collar external area, (in ) 2 A EXTC = Collar external area, (in ) 2 A INTC OD B = Body outside diam eter, (in) OD J = Joint outside diam eter, (in) ID B = Body inside diam eter, (in) ID J = Joint inside diam eter, (in) 124 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Compare The Cyclic Stress Against The Derated Fatigue Endurance Limit The fatigue ratio is the combined bending and buckling stress divided by the fatigue endurance limit. Some judgment is required in using the fatigue endurance limit (FEL), because the limit is normally determined for a number of cycles of pipe rotation. The number of cycles for the fatigue endurance limits is approximately taken at 107 rotations; this is the level of cyclic stress beyond which the material is immune to fatigue failure. This is normally equivalent to the pipe drilling for 100000’ at 60ft/hr at 100 rpm. The relationship between fatigue stress (S) and number of cycles to failure (N) is known as the S-N curve. The following chart is an idealized S-N curve for G105 pipe that has a yield of 105 Kpsi and a fatigue endurance limit of 30 Kpsi. Using the chart you can see that a pipe may yield at a lower number of cycles at an intermediate stress between the fatigue endurance limit and the tensile stress limit. Friction Factors A friction factor is sometimes referred to as the coefficient of friction. The friction factor represents the prevailing friction between the wellbore or casing and the work string. Higher coefficients of friction Landmark WELLPLAN 125 Chapter 3: Torque Drag Analysis result in greater resistance to the movement of the work string as it is run in, pulled out, or rotated in the wellbore. A friction factor of zero implies there is no friction in the well, which is an impossible situation. A friction factor of one suggests all of the normal (contact) force has been translated into drag force. Refer to the Drag Force calculations (page 119) for related information. Friction depends on the two surfaces in contact, as well as the lubrication properties of the drilling fluid. In addition to friction, the results of physical mechanisms acting on the work string are reflected in the selection of the friction factor. There are a number of physical mechanisms, including stabilizer gouging, key seats, and swelling formations, that contribute to the torque and drag of the work string. These mechanisms can cause the hook loads and torques to be higher or lower than expected. The wellbore path (doglegs or tortuosity) can also contribute to the loading forces on a work string. Refer to Tortuosity in this section (page 137) for more information. Models The Torque Drag module offers you the choice of two methods to use to model the string in the wellbore. The soft string model has been the basis of the WELLPLAN Torque Drag analysis for years. This model is commonly used throughout the industry for this type of analysis. The stiff string model was added to the module with the latest release of the software. Both models analyze the string in 30-foot sections. The primary difference between the models is the method of calculating the normal force acting on the string as a result of the string placement in the wellbore. Each of the models are described in the following sections. Pipe Wall Thickness Modification Due to Pipe Class Drill pipe wall thickness is modified according to the class specified for the pipe on the String Editor. The class specified indicates the wall thickness modification as a percentage of the drillpipe outside diameter. Drill pipe classes can be entered or edited on the Class option of the Tubular Properties submenu of the Tools Menu. The outside diameter is modified as follows: 126 WELLPLAN Landmark Chapter 3: Torque Drag Analysis ODnew = c ∗ ODold + IDold (1 − c ) Where: OD new = Calculated outside diam eter based on pipe class %WallThickn ess c = and is based on pipe class specified 100 OD old = O utside diam eter as specified on the String Editor ID old = Inside diam eter as specified on the String Editor Sheave Friction Sheave friction corrections are applied to all measured weight calculations when you have indicated on the Torque Drag Setup Data dialog that you want to apply this correction. n(e − 1)(H r + Wtb ) Lr = 1 e1 − n e n(1 − e )( H l + Wtb ) Ll = ( 1 − en ) Where: Landmark WELLPLAN 127 Chapter 3: Torque Drag Analysis Lr = Weight indicator reading while raising Ll = Weight indicator reading while lowering Hr = Hook load while raising, calculated in analysis Hl = Hook load while lowering, calculated in analysis Wtb = Weight of travelling block, user input n = Number of lines between the blocks e = Individual sheave efficiency Side Force for Soft String Model The side force or normal force is a measurement of the force exerted by the wellbore onto the work string. In the diagram below, the forces acting on a small segment of work string lying in an inclined hole are shown. In this simple diagram, the segment is not moving. From this diagram we can see that the normal force acts in a direction perpendicular to the inclined surface. The weight of the work string acts downward in the direction of gravity. Another force, the drag force, is also acting on the segment. The drag force always acts in the opposite direction of motion. The segment does not slide down the inclined plane because of the drag force. The magnitude of the drag force depends on the normal force, and the coefficient of friction between the inclined 128 WELLPLAN Landmark Chapter 3: Torque Drag Analysis plane and the segment. The coefficient of friction is a means to define the friction between the wellbore wall and the work string. FN = (FT ∆α Sin(Φ )) + (FT ∆Θ + WL Sin(Φ )) 2 2 Where: FN = Normal or side force FT = Axial force at bottom of section calculated using Buoyancy Method ∆α = Change in azimuth over section length Φ = Average inclination over the section ∆Θ = Change in inclination over section length L = Section length W = Buoyed weight of the section Where: FN= Normal Force FD = Drag Force W = Weight of segment Landmark WELLPLAN 129 Chapter 3: Torque Drag Analysis Soft String Model The soft string model is based on Dawson’s cable model, or soft string model. As the name implies, in this model the work string (such as drillstring or casing, and so forth) is considered to be a flexible cable or string with no associated bending stiffness. Since there is no bending stiffness, there is no standoff between the BHA and the wellbore wall due to stabilizers or other upsets. When determining contact forces, the work string is assumed to lie against the side of the wellbore. However, within the soft string analysis it is actually considered to follow the center line of the wellbore. When determining the contact or normal force, the contact between the string and the wellbore is assumed to occur at the midpoint of each string segment. Stiff String Model The stiff string model uses the mathematical finite element analysis to determine the forces acting on the string. This model considers the tubular stiffness and the tubular joint-to-hole wall clearance. The model modifies the stiffness for compressive forces. Like the soft string model, it calculates single point weight concentrations so determining the contact force per unit area is not possible. Stiff String analysis should be used to complete the following tasks: • Evaluate a work string containing stiff tubulars run in a well with an build rate of at least 15 deg/100 ft. • Analyze running stiff casing in a well. • Observe buckling using the Position Plot. • Analyze work string containing upsets found on stabilizers or friction reduction devices. The stiff string model analyzes the string by dividing it into sections (elements) equal to the lesser of the component length or 30 feet. The model computes the side force at the center point of each element. The side force is used to compute the torque and drag change from one element to the next element. The analysis of each element involves analyzing the nodes defining the end points of each element. The detailed analysis of each node involves creating a local mesh of 10 to 20 elements around the node. Each 130 WELLPLAN Landmark Chapter 3: Torque Drag Analysis element is given the same dimensions and properties as the corresponding full drill string portion. If the node length exceeds the maximum column-buckling load for the section, the node is further broken into fractional lengths to keep each section below the buckling threshold. This is why the analysis may take considerably longer when large compressive loads are applied. This short section is solved by solving each individual junction node for moments and forces, then displacing it to a point of zero force. If this position is beyond the hole wall, a restorative force is applied to keep it in the hole. This process is repeated for each node in the short beam until they reach their “relaxed” state. The stiff string produces slightly different results when run “top down” or “bottom up.” The difference is explained because the direction of analysis is reversed. The length of beam selected for each stiff analysis has been selected to optimize speed while maintaining reliable consistent results. The following illustrations depict an inclined beam section with length L. P is the axial force, and Fv, F1, and F2 are the calculated ends or contact forces caused by weight W. M = End Moment Fv = End Force I L P Fv M1 M2 W F1 F2 L Landmark WELLPLAN 131 Chapter 3: Torque Drag Analysis Stress In the analysis, many stress calculations are performed using the following equations. These calculations include the effects of: l Axial stress due to hydrostatic and mechanical loading l Bending stress approximated from wellbore curvature l Bending stress due to buckling l Torsional stress from twist l Transverse shear stress from contact l Hoop stress due to internal and external pressure l Radial stress due to internal and external pressure Calculated stress data is available on the Stress Graph, Summary Report or Stress Data table. σ ij = stress i = stress type j = location Stress types: Location: r = Radial 1 = outside pipe wall s = Transverse shear 2 = inside pipe wall h = Hoop t = Torsion a = Axial Von Mises Stress (σ − σ hj ) + (σ aj − σ rj ) + (σ hj − σ aj ) + 6σ sj + 6σ tj 2 2 2 2 2 σ VM = rj 2 Note: The von Mises stress is calculated on the inside and outside of the pipe wall. The maximum stress calculated for these two locations is presented in the reports, graphs, and tables. 132 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Radial Stress σ r1 = − Pe σ r 2 = − Pi Transverse Shear Stress 2 Fn σ s1 = σ s 2 = A Hoop Stress [ σ h1 = 2 ri Pi − ri + ro Pe 2 ( 2 2 ) ] (r o 2 − ri 2 ) σ h2 = [(r + ro )P − 2 r P (r − ri )] 2 2 2 2 2 i i o e o Torsional Stress σ t 1 = 12 ro T J σ t 2 = 12 ri T J Bending Stress σ bend 1 = ro EκM 68754.9 σ bend 2 = ri EκM 68754.9 Buckling Stress (only calculated if buckling occurs) Landmark WELLPLAN 133 Chapter 3: Torque Drag Analysis σ buck 1 = ro R c Fa 2 I σ buck 2 = − ri R c Fa 2 I Axial Stress (tension + bending + buckling) σ a 1 = F a A + σ bend 1 + σ buck 1 σ a 2 = F a A + σ bend 2 + σ buck 2 Where: ri = Inside pipe radius (in) ro = O utside pipe radius (in), as m odified by the pipe class Fn = Norm al (side) force, (lb) Fa = Axial force (lb) as calculated with pressure area m ethod T = Torque (ft-lb) E = M odulus of elasticity (psi) Pi = Pipe internal pressure (psi) Pe = Pipe external pressure (psi) κ = W ellbore curv ature as dogleg sev erity (deg/100ft) for soft string m odel. Stiff string m odel calculates local string curv ature. J = Polar m om ent of inertia W here: ( J body = π 32 B od − B id 4 4 ) =π 32 (J − J id ) 4 4 J jo int od B od = body outside diam eter, in B id = body inside diam eter, in J od = joint outside diam eter, in J id = joint inside diam eter, in 134 WELLPLAN Landmark Chapter 3: Torque Drag Analysis A = Cross sectional area of component I = Moment of inertia Rc = Maximum distance from workstring to wellbore wall (in) M = Bending Stress Magnification Factor Stretch Total stretch in the work string is computed as the sum of three components. These three components consider the stretch due to axial load, buckling, and ballooning. Ballooning is caused by differential pressure inside and outside of the work string. Total Stretch = ∆LHL + ∆LBuck + ∆LBalloon Stretch due to axial load This term is based on Hooke’s Law. The first term reflects the constant load in the string, while the second term reflects the linear change in the load. F ∗L ∆F ∗ L ∆LHL = + A∗ E 2∗ A∗ E Where: ∆LHL = Change in length due to the Hooke’s Law mechanism F = Axial force as determined by the pressure area method ∆F = Change in pressure area axial force over component length A = Cross sectional area of component E = Young’s Modulus of component Stretch due to buckling If buckling occurs, the additional stretch in the buckled section of the work string is calculated using the following equation. Landmark WELLPLAN 135 Chapter 3: Torque Drag Analysis r 2 ∗ F ∗ L r 2 ∗ ∆F ∗ L ∆LBuck = + 4∗ E ∗ I 8∗ E ∗ I Where: ∆L Buck = Change in length due to buckling F = Axial force as determined by the pressure area metho ∆F = Change in pressure area axial force over component E = Young’s Modulus of component I = Moment of Inertia r = Clearance between the wellbore wall and the work string component Stretch due to ballooning Stretch due to ballooning is caused by differential pressure inside and outside of the work string, and is defined by the following equation. ∆LBalloon = −v∗L ( E ∗ R −1 2 [( ) ( ∗ ρ s − R 2 ∗ ρ a ∗ L + 2 ∗ Ps − R 2 ∗ Pa ) )] Where: ∆LBalloon = Change in length due to ballooning mechanism L = Length of work string component element R = Ration of component outside diameter/inside diameter E = Young’s Modulus of component ν = Poisson’s Ratio of component ρs = Mud density inside work string component ρa = Mud density in annulus at depth of work string component Ps = Surface pressure, work string side Pa = Surface pressure, annulus side 136 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Tortuosity Wellbore tortuosity is a measure of the random meandering that occur in a well during drilling operations. In designing a well, tortuosity or rippling is not normally modeled during directional well path planning. Typically, a survey file is generated based on “ideal” trajectories which follow smooth paths governed by the survey calculation method. WELLPLAN uses the minimum curvature method. Similarly, during actual drilling operations, “wiggle” may occur between consecutive survey stations, even though the actual well path appears to match the “ideal” plan at the survey station measurement point. The recording of the well’s precise tortuosity can be captured only through the use of closer and closer survey stations, although this may be impractical. In both the design case and the operational case, the degree of tortuosity is a factor on the overall loading (both torque and drag) on a particular work string. The “smoother” the well, the less the frictional effects. Modelling of wellbore tortuosity has been recognized as especially significant at the planning stage, enabling more realistic load predictions to be established. Torque Torque is calculated using the following equation. A τ = FN ∗ r ∗ µ ∗ V Where: Landmark WELLPLAN 137 Chapter 3: Torque Drag Analysis T = Trip speed RPM A = Angular speed = diameter ∗ π ∗ 60 V = Resultant speed = (T 2 + A2 ) FN = Side or normal force µ = Coefficient of friction r = Radius of component (for collars the OD of the collar is used for drill pipe, heavy weight and casing, the OD of the tool joint is used for stabilizers the OD of the blade is used) FD = Drag force τ = Torque The side force or normal force is a measurement of the force exerted by the wellbore onto the work string. In the diagram below, the forces acting on a small segment of work string lying in an inclined hole are shown. In this simple diagram, the segment is not moving. From this diagram we can see that the normal force acts in a direction 138 WELLPLAN Landmark Chapter 3: Torque Drag Analysis perpendicular to the inclined surface. The weight of the work string acts downward in the direction of gravity. Another force, the drag force, is also acting on the segment. The drag force always acts in the opposite direction of motion. The segment does not slide down the inclined plane because of the drag force. The magnitude of the drag force depends on the normal force, and the coefficient of friction between the inclined plane and the segment. The coefficient of friction is a means to define the friction between the wellbore wall and the work string. Where: FN = Normal Force FD = Drag Force W = Weight of segment Twist Twist in the work string is calculated along the string for each segment, and is accumulated along the length of the work string. Twist is reported as “windup” on the reports. TL Θ= JG Where: Landmark WELLPLAN 139 Chapter 3: Torque Drag Analysis Θ = Angle of twist (radians) L = Length of com ponent T = Torque (ft-lb) E = M odulus of elasticity (psi) E G = M odulus of rigidity = 2 + 2ν ν = Poisson’s ratio J = Polar m om ent of inertia W here: Pipe: ( J body = π 32 B od − B id 4 4 ) =π 32 (J − J id ) 4 4 J jo int od B od = Body outside diam eter, in B id = Body inside diam eter, in J od = Joint outside diam eter, in J id = Joint inside diam eter, in (J ∗J ) J = body jo int (.95 J jo int + . 05 J body ) Collar: π J = 32 (B OD4 − B ID4 ) Viscous Drag Viscous drag is additional drag force acting on the work string due to hydraulic effects while tripping or rotating. The fluid forces are determined for “steady” pipe movement, and not for fluid acceleration effects. You can elect to include viscous drag on the Torque Drag Setup Data dialog. The additional force due to viscous drag is calculated as follows. Note that this drag force is added to the drag force calculated in Drag Force Calculations. ∆P.π .( Dh2 − D p2 ).D p ∆Force = 4.( Dh − D p ). 140 WELLPLAN Landmark Chapter 3: Torque Drag Analysis There are no direct computations of fluid drag due to pipe rotation. The method shown here derives from the analysis of the Fann Viscometer given in Applied Drilling Engineering. Compute the Shear Rate in the Annulus due to pipe rotation. 4.π .RPM / 60 SR = ( D . 1 / D p2 − 1 / Dh2 2 p ) Given the shear rate, the shear stress is computed directly from the viscosity equations for the fluid type. The 479 in the equations below is a conversion from Centipoise to equivalent lb/100 ft2. Bingham Plastic τ t = YP + PV .SR / 479 Power Law τ t = K .SR n / 479 if K is Cp or 4.79 if K is dyn/cm Herschel Bulkley τ t = ZG + K .SR n / 479 if K is Cp or 4.79 if K is dyn/cm No consideration is made to laminar or turbulent flow in this derivation. Additionally the combined hydraulic effects of trip movement and rotation are ignored, which would accelerate the onset of turbulent flow. Given the shear stress at the pipe wall (in lb/100ft2), the torque on the pipe is computed from the surface area of the pipe and the torsional radius. Landmark WELLPLAN 141 Chapter 3: Torque Drag Analysis ∆Torque = τ t .2.π .L.( D p / 24) 2 / 100 In the case of rotational torque the forces are equal and opposite between the pipe and the hole, although we are interested in the torque on the pipe and not the reaction from the hole. Where: Dh = H ole D iam eter (in) Dh = P ipe D iam eter (in) ∆P = A nnular pressure loss calculated according to rheological m odel selected Vp = Linear S peed of P ipe (ft/m in) RPM = R otational S peed of P ipe (rev olutions/m in) YP = Y ield P oint (lbs/100ft2) PV = P lastic V iscosity (cp) ZG = Z ero G el Y ield (lbs/100ft2) 142 WELLPLAN Landmark Chapter 3: Torque Drag Analysis References General “The Neutral Zones in Drill Pipe and Casing and Their Significance in Relation to Buckling and Collapse”, Klinkenberg, A., Royal Dutch Shell Group, South Western Division of Production, Beaumont, Texas, March 1951. “Drillstring Design for Directional Wells, Corbett, K.T., and Dawson, R., IADC Drilling Technology Conference, Dallas, March 1984. “Uses and Limitations of Drillstring Tension and Torque Model to Monitor Hole Conditions”, Brett, J.F., Bechett, A.D., Holt, C.A., and Smith, D.L., SPE 16664. “Developing a Platform Strategy and Predicting Torque Losses for Modelled Directional Wells in the Amauligak Field of the Beaufort Sea, Canada”, Lesso Jr., W.G., Mullens, E., and Daudey, J., SPE 19550. Bending Stress Magnification Factor “Bending Stress Magnification in Constant Curvature Doglegs With Impact on Drillstring and Casing”, Paslay, P.R., and Cernocky, E.P., SPE 22547. Buckling “A Buckling Criterion for Constant Curvature Wellbores”, Mitchell, R., Landmark Graphics, SPE 52901. “A Study of the Buckling of Rotary Drilling Strings, Lubinski, A., API Drilling and Production Practice, 1950. “Drillpipe Buckling in Inclined Holes”, Dawson,R., and Paslay, P.R., SPE 11167, September 1982. “Buckling Behavior of Well Tubing: The Packer Effect, by Mitchell, R.F., SPE Journal, October 1982. Landmark WELLPLAN 143 Chapter 3: Torque Drag Analysis “Frictional Forces in Helical Buckling of Tubing”, Mitchell, R.F., SPE 13064. “New Design Considerations for Tubing and Casing Buckling in Inclined Wells”, Cheatham, J.B., and Chen, Y.C., OTC 5826, May 1988. “Tubing and Casing Buckling in Horizontal Wells”, Chen, Y.C., Lin, Y.H., and Cheatham, J.B., JPT, February 1989. “Buckling of Pipe and Tubing Constrained Inside Inclined Wells”, Chen, Y.C., Adnan, S., OTC 7323. “Effects of Well Deviation on Helical Buckling”, Mitchell, R.F., SPE Drilling & Completions, SPE 29462, March 1997. “Buckling Analysis in Deviated Wells: A Practical Method,” SPE Drilling & Completions, SPE 36761, March 1999. Fatigue “Deformation and Fracture Mechanics of Engineering Materials”, by Richard W.Herzberg, 3rd Edition 1989, Wiley. Sheave Friction “The Determination of True Hook and Line Tension Under Dynamic Conditions”, by Luke & Juvkam-Wold, IADC/SPE 23859. “Analysis Improves Accuracy of Weight Indicator Reading”, by Dangerfield, Oil and Gas Journal, August 10, 1987. Side Force Calculations “Torque and Drag in Directional Wells – Prediction and Measurement”, Johancsik, C.A., Friesen, D.B., and Dawson, Rapier, Journal of Petroleum Technology, June 1984, pages 987-992. “Drilling and Completing Horizontal Wells With Coiled Tubing”, Wu, Jiang, and Juvkam-Wold, H.C., SPE 26336. 144 WELLPLAN Landmark Chapter 3: Torque Drag Analysis Stiff String Model “Background to Buckling”, Brown & Poulson, University of Swansea, Section 3.4 Analysis of Elastic Rigid Jointed Frameworks (with sway). “Engineering Formulas”, Gieck, Kurt, Fourth Ed. McGraw Hill 1983, Section P13, Deflection of Beams in Bending. Landmark WELLPLAN 145 Chapter 3: Torque Drag Analysis 146 WELLPLAN Landmark Chapter 4 Hydraulics Analysis Hydraulics can be used to simulate the dynamic pressure losses in the rig’s circulating system, and to provide analytical tools to optimize hydraulics. Overview In this section of the course, you will become familiar with all aspects of using the Hydraulics module. You will also become familiar with the data presented on reports, and plots. To reinforce what you learn in the class lecture, you will have the opportunity to complete several exercises designed to prepare you for using the module outside of class. The information presented in this chapter can be used as a study guide during the course, and can also be used as a reference for future analysis. At the end of this chapter you will find the methodology used for each analysis mode. The methodology is useful for understanding data requirements, analysis results, as well as the theory used as the basis for the analysis. Supporting calculations and references for additional reading are also included in this chapter. Landmark WELLPLAN 147 Chapter 4: Hydraulics Analysis Hydraulics Analysis: An Introduction The Hydraulics module can be used to simulate the dynamic pressure losses in the rig’s circulating system, and to provide analytical tools to optimize hydraulics. The module provides several rheological models, including Bingham Plastic, Power Law, and Herschel Bulkley. The chosen rheological model provides the basis for the pressure loss calculations. You may chose to optimize hydraulics based on maximum hydraulic horsepower, maximum impact force, maximum nozzle velocity, or percent pressure loss at bit. Or you may optimize hydraulics based on recorded pressure loss and flow rate data using Scott’s Method. A hole cleaning model is also provided that can assist with evaluation cuttings build up in an actual well, or as a tool to help evaluate mud systems. Starting Hydraulics Analysis There are two ways to begin the Hydraulics Module. You can select Hydraulics from the Modules Menu, and then select the appropriate analysis mode. You can also click the Hydraulics Button and then select the appropriate analysis mode from the drop down list. Available Analysis Modes l Pressure: Pump Rate Range: Calculate pressure losses for each section in the workstring, annulus, the surface equipment and bit, and ECDs for a specified range of flowrates. l Pressure: Pump Rate Fixed: Calculate pressure losses for each section in the workstring, annulus, the surface equipment and bit for one pump rate. l Annular Velocity Analysis: Calculate annular velocities at specified flowrates and the critical flowrates for each section in the work string. l Swab/Surge Tripping Schedule: Calculate a tripping schedule that will not exceed a specified pressure change while moving the work string in or out of the hole. 148 WELLPLAN Landmark Chapter 4: Hydraulics Analysis l Swab/Surge Pressure and ECD: Calculate the actual pressure and ECD that will occur when the work string is tripped in or out of the hole. l Graphical Analysis: Examine the effects of changing flowrate and TFA on a number of hydraulics parameters. l Optimization Planning: Calculate the flowrate and nozzle configuration to optimize bit hydraulics based on several common criteria. l Optimization Well Site: Determine nozzle configuration for optimal hydraulics using recorded rig circulating pressures. These calculations are based on Scott’s method, and uses only data specified on the input dialog. l Weight Up: Calculate the amount of weight up or dilution material required to adjust mud weight to a specific value. l Hole Cleaning Operational: Determine the cutting concentration percentage, bed height, and critical transport velocity flow rate in the wellbore using the current string, wellbore, fluid and survey. l Hole Cleaning Parametric: Determine the cuttings concentration percentage, bed height, and critical transport velocity flow rate for a range of pump rates for all inclinations from 0 to 90 degrees (in five degree increments). This mode uses data specified on the input dialog, and does not use the current string, wellbore, or survey. Landmark WELLPLAN 149 Chapter 4: Hydraulics Analysis Using Pressure: Pump Rate Range Analysis Mode The system pressure losses can be calculated for a range of flowrates. All pressure losses are calculated using the Rheological Model selected on the Fluid Editor. The calculations will be performed at the Minimum and Maximum Flowrate you specify, as well as at each Increment Flowrate specified, for a maximum of five flowrates on the reports. On the ECD Depths dialog, you can specify up to five depths at which to calculate ECD. For each flowrate iteration, the following calculations will be performed. l bit hydraulic power l ratio of bit hydraulic power to total cross-sectional area of the bit l bit impact force l bit nozzle velocity l ECDs at user defined depths Select Pressure Pump Rate Range Analysis Mode Select desired mode from drop down list. Entering Case Data The Pump Rate Range analysis used the well data entered on the Case menu, and the analysis data entered on the Parameter menu. 150 WELLPLAN Landmark Chapter 4: Hydraulics Analysis For discussion on the Case menu items that are common to all WELLPLAN modules, please refer to the Basics chapter of this manual. The common Case menu options include: the General, Offshore, Wellbore Editor, String Editor, and Deviation menu. Case menu options for Pump Rate Range analysis Define Fluid Properties and Rheological Model Use the Case →Fluid Editor tabs to specify the rheological model and specify other basic characteristics about simple drilling muds, standard drilling muds, or cement slurries. These tabs were discussed in the Basics chapter of this manual. The Fluid Editor dialog has three tabs: l Standard Muds Tab - Use this tab to specify the basic characteristics of simple or standard drilling muds. l Cement Slurries Tab - Use this tab to specify basic cement slurry characteristics. l Fluid Selector Tab - Use this tab to select the fluid you want to use in the analysis from a list of previously defined fluids. Fluid Selector Tab Use the Case→Fluid Editor→Fluid Selector tab to select the fluid you want to use in the analysis. This list contains all fluids that were defined for the case through the Standard Muds or Cement Slurries tabs. Landmark WELLPLAN 151 Chapter 4: Hydraulics Analysis Select the fluid you want to use in the analysis from the drop down list. This list will include all fluids define on the Standard Muds or Cement Slurries tabs. This tab contains some of the information defining the selected fluid. For more details, refer to the other tabs on the Fluid Editor. Specify the Undisturbed Temperature Profile The effects of temperature on fluid rheology can be modelled within the Hydraulics module. Entering data into the Case→Undisturbed Temperature dialog is explained in the Basics Chapter of this manual. Eccentricity Use Case →Eccentricity spreadsheet to specify the eccentricity ratio of the annuli at different depths. Eccentricity reduces the pressure drop for annular flow. The Hydraulics module will automatically calculate eccentricity using the tool joint diameter regardless of what is entered in the eccentricity spreadsheet. If you specify eccentricity in the spreadsheet, and the calculated tool joint eccentricity is less than the specified eccentricity, the internally calculated tool joint eccentricity will be used for the engineering calculations. If you check the Concentric Annulus box, the string will be centered in the wellbore regardless of the wellbore deviation or the calculated tool joint eccentricity. 152 WELLPLAN Landmark Chapter 4: Hydraulics Analysis An eccentric annulus ratio is defined by specifying the displacement from the centerline divided by the radial clearance outside the moving pipe. You need to define the eccentricity for each annular section and then its eccentric value. Define the annular section by specifying a depth in the Depth cell for the row, and then specify an eccentric value for the section. A value of zero is concentric and a value of 1 is fully eccentric. You can use the WELLPLAN Torque Drag module Position Plot to determine the position of the string in the wellbore. The position in the wellbore can be used to determine the eccentricity. Remember, you must use a stiff string analysis to be able to generate a Position plot. Check the Concentric Annulus box to indicate the entire string is concentric in the annulus. If this box is checked, data in the spreadsheet will not be used. Enter eccentricity = 1 to indicate string positioned against the wellbore The Eccentriciy spreadsheet is only available when you are using the Herschel Bulkley rheology model. Select the rheology model on the Case →Fluid Editor→Standard Muds tab. If you are using the Herschel Bulkley rheology model, and the Eccentricity spreadsheet is still not availble, try opening the Wellbore Editor and then reopening the Eccentricity spreadsheet. Specify Circulating System Equipment You can use the Case →Circulating System tabs to specify the surface equipment configuration, maximum working pressure, and mud pump information. The Surface Equipment tab is designed to specify what surface equipment is used, and what the rated maximum working pressure is. You can use a predefined configuration, or define your own. Landmark WELLPLAN 153 Chapter 4: Hydraulics Analysis It is necessary to specify the surface equipment configuration because this information is used to account for pressure losses incurred in the pumps and the piping between the pumps and the workstring. If you don’t specify a surface equipment configuration, you must specify the pressure loss anticipated through the surface equipment. Click the Specify Pressure Loss radio Enter the rated button to enter the maximum working expected pressure pressure loss through the surface equipment. Select the category of surface equipment Or, you can calculate that you want to use the surface equipment from the drop down pressure loss by list. You don’t need clicking the Calculate to select or specify a Pressure Loss radio surface equipment button. configuration if you specify the pressure If you want to loss. calculate the pressure loss, you must select/ specify the surface equipment configuration. The Case →Circulating System→Mud Pumps tab is used to define working parameters of the available pumps. You can specify whether the pump is active or inactive. 154 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Check box to specify active pump Insert a new row by entering data in the next empty row, or by highlighting a row and pressing the Insert key on your keyboard. Delete a row by highlighting it and pressing the Delete key on your keyboard. Define Pump Rate Range The Parameter →Rates dialog is used to specify pump information that will be used to calculate system pressures losses for a range of pump rates. The range of pump rates are determined by the Minimum, Maximum, and Increment Pump Rate specified in the Pump Rate section of the dialog. The Minimum Pump Rate specifies where the pressure loss analysis calculations will begin. This rate will be increased by the Increment Pump Rate until the Maximum Pump Rate is reached or five rates (including the Minimum and Maximum Rates) have been analyzed. In the Pumping Constraints section of the dialog, enter the maximum pump discharge pressure that the pump is capable of. If you are using more than one pump, enter the minimum pump pressure of all active pump’s maximum pump pressures. You must also enter the Maximum Pump Power the pump can produce. Refer to the Pump Power Calculations for more information. Press the Default from Pump Data Button to use the Maximum Pump Pressure, and Maximum Pump Power calculated from the information entered on the Circulating System→Mud Pumps Tab. Refer to the Pump Pressure Calculations or Pump Power Calculations for more information. The Default from Pump Data button will not be available if you have not specified a surface equipment configuration on the Landmark WELLPLAN 155 Chapter 4: Hydraulics Analysis Circulating System→Surface Equipment Tab, and indicated at least one active pump on the Circulating System→Mud Pumps Tab. Check the Include Tool Joint Pressure Losses box to include tool joint pressure losses in the calculations. Tool joint pressure losses are sometimes referred to as minor pressure losses. Pressure losses due to tool joint upset in the annulus are accounted for in the calculations by considering the cross-sectional area change in the annulus regardless of whether or not this box is checked. However, in these calculations the length of the tool joint is not considered. Check the Use String Editor box to use the nozzle configuration entered for the bit component on the String Editor. Click the Nozzles button to gain access to the Nozzles Dialog. On this dialog, you may view the nozzle configuration currently on the String Editor or you may enter a different nozzle configuration for use in this analysis Specify the range of pump rates to analyze Enter pump data Roughness affects friction pressure losses in turbulent flow only. The nominal value of surface roughness for new steel pipe is 0.0018 inches. Old or corroded pipe can have values up to .0072 inches. This factor is more important in deep wells using old tubulars. Check box to include tool joint pressure losses Mark this check box to update the fluid rheology using the formation temperature defined in the Undisturbed Temperature dialog. Check box to use String Editor nozzles, or click the Nozzles button to use other nozzles Specify Nozzle Configuration The Nozzles dialog is accessible via the Nozzles button. The Nozzles dialog consists of two tabs. One tab displays the current nozzle configuration specified on the String Editor, and the other tab allows specification of different nozzle configurations for analysis. If a tested 156 WELLPLAN Landmark Chapter 4: Hydraulics Analysis nozzle configuration results are favorable, you may copy this configuration to the bit specified in the String Editor. The String tab displays the nozzle configuration specified on the String Editor. You can change the String Editor nozzles using this tab. Four nozzles sizes can be specified and the Total Flow Area will be calculated Specify the Total Flow Area if you want to use a certain TFA rather than nozzles sizes. The Local tab can be used to specify any nozzle configuration you want to analyze. If you determine this configuration is optimal, then you may copy the nozzle configuration to the String Editor. The advantage to changing the nozzles using this tab rather than the String Tab is that the String Editor nozzles will not be altered unless you click the Copy to String Button. Landmark WELLPLAN 157 Chapter 4: Hydraulics Analysis Four nozzles sizes can be specified and the Total Flow Area will be calculated Specify the Total Flow Area if you want to use a certain TFA rather than nozzles sizes. Click to copy nozzles to String Editor Set ECD Calculation Depths On the Parameter →ECD Depths dialog, enter up to five measured depths you would like ECD (equivalent circulating density) calculated. ECD may be calculated at any depth. Commonly ECD is calculated at the last casing shoe. The ECD of the mud is the mud weight that would exert the circulating pressures under static conditions at the specified depth. Enter up to five depths to calculated ECD for Analyzing Results Results for the Pressure: Pump Rate Range analysis are presented in a plot and a report. All results are available using the View Menu. 158 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Plot The Pressure Loss Plot displays the system pressure loss, as well as bit, string and annulus pressure losses for the range of flowrates specified on the Rates Dialog. Each curve on the graph represents one type of pressure loss. Pressure loss calculation are based on the rheological selected on the Fluid Editor. Annular volumes are calculated based on information entered on the String Editor and the Wellbore Editor. Maximum pump pressure is indicated on plot. The maximum pump pressure is input on the Case →Circulating System→Mud Pumps tab. Separate curves for bit, string, annulus, and system pressure losses Report Options The Report Options Dialog is used to specify what additional information will be included on the report. Using this dialog, you can include or exclude much of the information defining the case you are analyzing. Check boxes to include desired information on the Pressure Loss Report Landmark WELLPLAN 159 Chapter 4: Hydraulics Analysis Report The Pressure Loss report will sum the total pressure loss and the hydraulic power across each work string section, both inside the string and in the annulus. For example, inside the work string, it calculates the total pressure loss across the entire drill pipe section, then the HWDP section, then the drill collar section. Similarly, in the annulus, it calculates the pressure drop across the entire drill pipe section, the HWDP section, etc. The pressure losses through the surface equipment are shown along with the total system pressure loss at the specified flow rate. Finally, the report splits the annulus into separate sections based on a change in either the wellbore effective diameter and/or a change in the outside diameter of the work string. For each annular section, the report displays the following information: • Hole OD • Pipe OD • Pressure loss • Average velocity • Reynolds number • Critical flowrate l Flow regime (laminar, transitional, or turbulent) This information is presented for each of the flow rates you specify. 160 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Using Pressure: Pump Rate Fixed Analysis Mode The pressures in the circulating system will be calculated at the flowrate specified on the Rate Dialog using the rheological model selected on the Fluid Editor. You can analyze the pressure (dynamic and static pressures combined) at any depth from surface to TD in the work string, annulus or the bit pressure. The static pressure losses are those due to the hydrostatic pressure of the mud. The dynamic pressure losses are the frictional pressure losses that occur during circulation of the mud at a specified flow rate. You can analyze these pressure losses in the Pressure Pump Rate Range report also. You can also analyze the ECD (Equivalent Circulating Density) at any depth. Starting Pressure Pump Rate Fixed Analysis Mode Select Pump Rate Fixed from drop down list. Entering Case Data The Pump Rate Fixed analysis used the well data entered on the Case menu, and the analysis data entered on the Parameter menu. For discussion on the Case menu items that are common to all WELLPLAN modules, please refer to the Basics chapter of this manual. The common Case menu options include: the General, Offshore, Wellbore Editor, String Editor, and Deviation menu. Refer to the Pressure: Pump Rate Range analysis mode for a detailed description of the Fluid Editor, Undisturbed Temperature dialog, Eccentricity spreadsheet, and the Circulating System Tabs. Landmark WELLPLAN 161 Chapter 4: Hydraulics Analysis Enter Pore Pressure Data The Case →Pore Pressure spreadsheet is used to define the pore pressure profile as a function of depth. To specify a pore pressure point, you must specify a TVD in the vertical depth cell, and a value in either the pore pressure cell or the equivalent mud weight (EMW) cell. If you set or change the value in the pore pressure cell, the EMW will be automatically calculated and vice versa. Each row defines a separate pore pressure region. Enter Fracture Gradient Data The Case →Frac Gradient spreadsheet is used to define the fracture gradient profile as a function of depth. To specify a fracture pressure, you must specify a TVD in the vertical depth cell, and a value in either the fracture pressure cell or the equivalent mud weight (EMW) cell. If you set or change the value in the fracture pressure cell, the EMW will be automatically calculated and vice versa. Each row defines a separate fracture gradient region. Define Pump Rate to Analyze Pump Rate is the only input required, and is the only flowrate that will be used to calculate the pressure losses. Pressure loss information can be used to optimize hydraulics based on several optimization criteria. A summary of the analysis results is displayed in the Quick Look section. For more detail on the information presented in the Quick Look section, refer to the online help. 162 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Enter flowrate to analyze Use String Editor nozzles, or specify your own using the Nozzles Button The Quick Look section displays a summary of the analysis Use this slider control to specify the pump rate instead of entering a value in the Pump Rate field located at the top of this dialog. You can specify any value between 1 and 2,500 gpm. The value you define with this control is displayed in the Pump Rate field. Analyzing Results In addition to the information in the Quick Look section, there are two plots available. These plots are available via the View menu. One plot is Pressure Loss vs. Measured Depth, and the other is ECD vs. Depth. Plots Pressure vs. Depth Plot You can use this plot to display the combined (hydrostatic and frictional) pressure losses through the workstring, annulus, or through the bit at any depth in the wellbore. From this graph you will not be able to determine what portion of the pressure loss results from static or dynamic losses. The plot also indicates the casing shoe setting depth, as well as the pore pressure and fracture gradients for all measured depths in the wellbore. The information presented on the plot pertains to the flowrate you specified on the Rate Dialog. The pressure losses are calculated based on the rheological method specified on the Fluid Editor. The shoe Landmark WELLPLAN 163 Chapter 4: Hydraulics Analysis setting depth is retrieved from the Wellbore Editor, and the pore pressure and fracture gradient information is found on the Pore Pressure and Fracture Gradient Editors. Annular pressure is between the pore and fracture pressures. Casing shoe Bit pressure loss Use the slider to change flowrate if you want to analyze another rate. ECD vs. Depth Plot Use this plot to determine the equivalent circulating density (ECD) in the annulus at any measured depth in the wellbore. The plot will display the pore pressure and fracture gradient expressed as a density for all measured depths. The shoe setting measured depth will also be indicated. The ECD is the density that would exert the circulating pressure under static conditions. The pore pressure and fracture gradients are displayed as density to facilitate comparison. The pressure losses are calculated based on the rheological method specified on the Fluid Editor. The shoe setting depth is retrieved from the Wellbore Editor, and the pore pressure and fracture gradient information is found on the Pore Pressure and Fracture Gradient Editors 164 WELLPLAN Landmark Chapter 4: Hydraulics Analysis ECD in the annulus for the current flowrate Pore pressure Casing shoe Landmark WELLPLAN 165 Chapter 4: Hydraulics Analysis Using Annular Velocity Analysis Mode Annular Velocity can be used to determine the flow regime and critical velocity for each section in the annulus for a range of flow rates. Critical velocity is the velocity resulting from the critical flow rate. For the Power Law and Bingham Plastic rheology models the critical flow rate is the flow rate required to produce a Reynold’s number greater than the critical Reynold’s number for laminar flow. The Reynold’s number is dependent on mud properties, the velocity the mud is traveling, and on the effective diameter of the work string, or annulus the mud is flowing through. Based on the calculated Reynold’s number and the rheological model you are using, it is possible to determine the flow regime of the mud. For regimes where the Reynold’s number lies between the critical values for laminar and turbulent flow, a state of transitional flow exists. For the Herschel-Bulkley rheology model the critical flow rate is the flow rate required to exceed the Ga number corresponding to laminar flow. The Ga number is dependent on mud properties, the velocity the mud is traveling, and on the effective diameter of the work string, or annulus the mud is flowing through. Based on the calculated Ga number and the rheological model you are using, it is possible to determine the flow regime of the mud. For regimes where the Ga number lies between the critical values for laminar and turbulent flow, a state of transitional flow exists. Select Annular Velocity Analysis Mode Select Annular Velocity from drop down list. Entering Case Data The Annular Velocity analysis uses the well data entered on the Case Menu, and the analysis data entered on the Parameter Menu. 166 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Since all options on the Case Menu items are common to all WELLPLAN modules, please refer to the Basics chapter of this manual. The common Case menu options include: the General, Offshore, Wellbore Editor, String Editor, and Deviation menu. Refer to the Pressure: Pump Rate Range analysis mode for a detailed description of the Fluid Editor. Define Pump Rates to Analyze The Rates Dialog is used to enter the range of flowrates to analyze. Up to 15 flow rates can be analyzed. Analyzing Results The analysis results are available via the View Menu. Plots Annular Velocity Plot Use this plot to determine the velocity of the fluid in the annulus for any measured depth in the wellbore for the range of flow rates you specified on the Rates Dialog. This graphical analysis calculates the annular velocity across each annulus section and compares the profile with the critical velocity. Note that when an annular velocity curve crosses the critical velocity curve, then the flow regime for that annulus section moves from laminar to either transitional or turbulent flow. The fluid velocity is calculated based on the rheological model selected on the Fluid Editor. Cross-sectional flow areas are determined from information input on the String Editor, and the Wellbore Editor. Landmark WELLPLAN 167 Chapter 4: Hydraulics Analysis Annular Velocity vs Measured Depth for each flowrate analyzed Annular velocity exceeding laminar flow Annular Pump Rate Plot Use this plot to determine the pump rate that will result in fluid flow outside of the laminar flow regime for any depth in the wellbore. Pump rates greater than the critical flow rate curve at any depth indicate that the flow regime moves out of laminar flow and into transitional or turbulent flow. You will not be able to determine from the graph whether the flow is transitional or turbulent. The calculations are based on the rheological model selected on the Fluid Editor. Cross-sectional flow areas are determined from information input on the String Editor, and the Wellbore Editor. 168 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Pump rates (at a given measured depth) greater than the Critical Pump Rate will result in transitional or turbulent flow Table Annulus Information Table This table contains pressure loss, and critical flow rates for a range of specified flowrates. You can use this table to determine the flow regime, critical pump rate, annular velocity, and pressure loss for all annular cross-sectional areas. This table presents information calculated based on the range of flowrates specified on the Rates Dialog, Fluid Editor, String Editor, Survey Editor and the Wellbore Editor. Landmark WELLPLAN 169 Chapter 4: Hydraulics Analysis Flow rates are specified Calculated using the Flow regimes can be on the Rates dialog. rheology model specified turbulent, laminar, or on Fluid Editor. transition. 170 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Using Swab/Surge Tripping Schedule The Swab/Surge Tripping Schedule analysis assists with determining the rate to trip in or out of the hole without exceeding a pressure change (Allowable Trip Margin) you specify. The surge or swab pressure changes in the well can be calculated with or without flow through an open-ended workstring, or without flow through a closed-ended workstring. You must specify the length of a stand of drill pipe or casing, and the Allowable Trip Margin. The Allowable Trip Margin is the maximum change in ECD at the bit, or casing shoe that you are willing to accept. Specifying a large value will allow large tripping speeds, whereas a low value will only allow low tripping speeds. Moving a work string is accompanied by a displacement of the mud in the hole that can result in pressure changes. Depending on the direction of the string movement, and the resulting mud displacement, these changes may add to the pressure exerted by the mud. If the pipe movement is downward, this may result in a surge pressure. If the pipe movement is upward, the changes may act in the opposite direction and produce a swab effect. These pressure changes may impair the stability of the hole through removal of the filter cake, or may even result in a blowout by dropping below the pore pressure, or lost circulation by exceeding the fracture pressure and fracturing the formation. Starting Swab/Surge Tripping Schedule Analysis Select Swab/Surge Tripping Schedule from drop down list. Entering Case Data The Swab/Surge Tripping Schedule analysis used the well data entered on the Case Menu, and the analysis data entered on the Parameter Menu. Landmark WELLPLAN 171 Chapter 4: Hydraulics Analysis For discussion on the Case Menu items that are common to all WELLPLAN modules, please refer to the Basics chapter of this manual. The common Case Menu options include: the General, Offshore, Wellbore Editor, String Editor, Fluid Editor, and Deviation Menu. Specify Circulating System Equipment You can use the Case →Circulating System tabs to specify the surface equipment configuration, maximum working pressure, and mud pump information. Refer to the Pressure: Pump Rate Range analysis mode for a detailed description of the Circulating System Tabs. Define Analysis Constraints Enter data in the Parameter →Operations Data dialog box to specify the conditions you want to use to calculate a Surge/Swab Tripping Schedule. For both swab and surge analysis, you can use a closed or open ended string by checking the appropriate boxes. You may perform an analysis with the end open and closed at the same time. If you are using an open ended string, you may also specify a flowrate. The stand length is used to used to calculate the tripping schedule as time per stand. Check the Use String Editor Box to use the nozzle configuration entered for the bit component on the String Editor. Press the Nozzles Button to gain access to the Nozzles Dialog. On this dialog, you may view the nozzle configuration currently on the String Editor or you may enter a different nozzle configuration for use in this analysis. 172 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Enter the maximum pressure change that you will allow during tripping out of the hole. Enter the length of a stand of drillpipe. Use String Editor nozzles, or specify your own using the Nozzles Button Analyzing Results Report Options The Report Options dialog is used to specify what additional information will be included on the report. Using this dialog, you can include or exclude much of the information defining the case you are analyzing. Refer to the Pressure: Pump Rate Range analysis mode discussion for more detail. Report Swab/Surge Report This report indicates the minimum allowable trip time per stand of pipe based on an allowable trip margin specified in ppg or psi. Depending on the situation, there could be one value for all stands or there could be a number of values for different sets of stands. If you specify a high value for the allowable trip margin, it is possible that the minimum time per stand (10 seconds) will not reach the allowable trip margin. In that case, the trip schedule produced will indicate that all stands can be tripped at the minimum time per stand. Conversely, if you specify a very small value for the allowable trip margin, it is possible that even at the maximum time per stand (200 seconds), the allowable trip margin will still be exceeded. In that case, Landmark WELLPLAN 173 Chapter 4: Hydraulics Analysis the trip schedule will show that all stands should be tripped at the maximum time per stand (200 seconds). 174 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Using Swab/Surge Pressure and ECD Analysis Mode The Swab/Surge Pressure and ECD analysis assists with determining the pressures and ECD at the bit, casing shoe and bottom of the hole as the pipe is tripped in or out of the hole at speeds ranging from 10 seconds per stand to 200 seconds per stand. The pressure and ECD calculations can be performed with or without flow through an open ended workstring, or without flow through a closed ended workstring. You must specify the length of a stand of drill pipe. Moving a work string is accompanied by a displacement of the mud in the hole that can result in pressure changes. Depending on the direction of the string movement, and the resulting mud displacement, these changes may add to the pressure exerted by the mud. If the pipe movement is downward, this may result in a surge pressure. If the pipe movement is upward, the changes may act in the opposite direction and produce a swab effect. These pressure changes may impair the stability of the hole through removal of the filter cake, or may even result in a blowout by dropping below the pore pressure or lost circulation by exceeding the fracture pressure and fracturing the formation. Starting Swab/Surge Pressure and ECD Analysis Mode Select Swab/Surge Pressure and ECD from mode data drop down list. Entering Case Data The Swab/Surge Pressure and ECD analysis used the well data entered on the Case menu, and the analysis data entered on the Parameter menu. Landmark WELLPLAN 175 Chapter 4: Hydraulics Analysis For discussion on the Case menu items that are common to all WELLPLAN modules, please refer to the Basics chapter of this manual. The common Case menu options include: the General, Offshore, Wellbore Editor, String Editor, Fluid Editor, and Deviation menu. Specify Circulating System Equipment You can use the Case →Circulating System tabs to specify the surface equipment configuration, maximum working pressure, and mud pump information. Refer to the Pressure: Pump Rate Range analysis mode for a detailed description of the Circulating System Tabs. Defining Operations Constraints Enter data in the Parameter →Operations Data dialog box to specify the conditions you want to use to calculate a Surge/Swab Tripping Schedule. For both swab and surge analysis, you can use a closed or open ended string by checking the appropriate boxes. You may perform an analysis with the end open and closed at the same time. If you are using an open ended string, you may also specify a flowrate. The stand length is used to used to calculate the tripping schedule as time per stand. Check the Use String Editor Box to use the nozzle configuration entered for the bit component on the String Editor. Press the Nozzles Button to gain access to the Nozzles Dialog. On this dialog, you may view the nozzle configuration currently on the String Editor or you may enter a different nozzle configuration for use in this analysis. Check closed if you don’t want fluid flow through the pipe. Enter the length of a stand of drillpipe. Use String Editor nozzles, or specify your own using the Nozzles Button 176 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Analyzing Results Plots There are four available plots: Swab Open End, Swab Closed End Surge Open End and Surge Closed End. Use these plots to determine the pressures and ECD (equivalent circulating density) to expect for trip speeds ranging from zero to 200 seconds per stand while tripping in or out. These plots pertains to swabbing or surging with an open or closed ended workstring. If the workstring is open ended, you may specify a flow rate through the string on the Operations Data Dialog. If you specified a flow rate greater than zero, the calculated pressure and ECD will include the effects of this flow rate. These plots will display the pressure and ECD at the bit, at the casing shoe (as the bit passes the shoe) and at total depth (TD). If the bit is at total depth (TD), the curves will overlay, and it may appear that the curves are missing from the plot. The bit depth is obtained from the String Editor, and the stand length is specified on the Operations Data Dialog. The casing shoe depth is retrieved from the Wellbore Editor. You may want to review the Swab/Surge report for additional information. ECD values read on this scale X-axis is time per stand Pressure read on this scale Landmark WELLPLAN 177 Chapter 4: Hydraulics Analysis Report Options The Report Options Dialog is used to specify what additional information will be included on the report. Using this dialog, you can include or exclude much of the information defining the case you are analyzing. Refer to the Pressure: Pump Rate Range analysis mode discussion for more detail. Report Swab/Surge Report This report indicates the minimum allowable trip time per stand of pipe. Depending on the situation, there could be one value for all stands or there could be a number of values for different sets of stands. If you specify a high value for the allowable trip margin, it is possible that the minimum time per stand (10 seconds) will not reach the allowable trip margin. In that case, the trip schedule produced will indicate that all stands can be tripped at the minimum time per stand. Conversely, if you specify a very small value for the allowable trip margin, it is possible that even at the maximum time per stand (200 seconds), the allowable trip margin will still be exceeded. In that case, the trip schedule will show that all stands should be tripped at the maximum time per stand (200 seconds). 178 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Using Graphical Analysis Mode Using the Graphical Analysis mode, you can determine the optimum flow rate and TFA resulting from specified criteria by examining a series of available graphs. The range of flowrates over which to perform the analysis begins at a very low flowrate, and is limited on the high end by the specified pump limits. Bit TFA (total flow area) is determined by using a calculated pressure loss at the bit, and the flowrate. The impact force, nozzle velocity and the hydraulic horsepower at the bit are calculated once the TFA, pressure loss at the bit and the flowrate are determined. Starting Graphical Analysis Mode Select Graphical Analysis from drop down list. Entering Case Data The Graphical Analysis mode uses the well data entered on the Case Menu, and the analysis data entered on the Parameter Menu. For discussion on the Case Menu items that are common to all WELLPLAN modules, please refer to the Basics chapter of this manual. The common Case Menu options include: the General, Offshore, Wellbore Editor, String Editor, Fluid Editor, and Deviation Menu. Specify Circulating System Equipment You can use the Case →Circulating System tabs to specify the surface equipment configuration, maximum working pressure, and mud pump information. Landmark WELLPLAN 179 Chapter 4: Hydraulics Analysis Refer to the Pressure: Pump Rate Range analysis mode for a detailed description of the Circulating System Tabs. Enter Pump Specifications Enter data in the Parameter →Pump Limits dialog box to specify the pump constraints that will be used as a basis for the Graphical Analysis. The Maximum Pump Pressure is the total system pressure loss. This pressure loss will be used to determine the flowrate based on the pressure loss calculations that pertain to the rheological model you have selected. The Maximum Pump Power establishes a boundary condition that will be displayed as a line on the graphical output from this analysis. Click the Default from Pump Data button to use the Maximum Pump Pressure, and Maximum Pump Power calculated from the information entered on the Circulating System, Mud Pumps Tab. Refer to the Mud Pump Calculations or Pump Power Calculations for more information. The Default from Pump Data button will not be available if you have not specified a surface equipment configuration on the Circulating System, Surface Equipment Tab, and indicated at least one active pump on the Circulating System, Mud Pumps Tab. Click Default from Pump Data button to default from active pumps Analyzing Results Plots All results are displayed in plots. 180 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Velocity at Bit Plot Use this plot to determine the velocity of the fluid through the bit for a range of flow rates and varied total flow area (TFA). The following steps can be used to determine the TFA for a specified flowrate or vice versa. 1. Look at the plot and determine the pump rate (x axis) and corresponding TFA (right side Y axis). Keep in mind the pump rate your pump(s) can produce. 2. Determine the velocity (left side Y axis) that corresponds to the pump rate and TFA determined in Step 1. The pump rate begins at zero and increases until the flow rate results in parasitic pressure losses equal to 100% of the total system pressure loss. (Essentially this case results in zero pressure loss at the bit.) The bit velocity is calculated by first determining the pressure loss through the bit. Pressure loss calculations are based on the rheological model selected on the Fluid Editor, and assume the total system pressure loss is equal to the maximum pump pressure entered on the Pump Limits Dialog. Based on the total system pressure loss, as well as the workstring, fluid, and wellbore information entered into the String Editor, Fluid Editor, and Wellbore Editor, we can determine the pressure loss at the bit. Knowing the pressure loss at the bit, and the flow rate the TFA can be calculated. From this, the velocity at the bit can be determined. This plot is used to determine the bit velocity and required flowrate or TFA given a flowrate or TFA. The bit velocity is 490 ft/s for a flowrate of 411 gpm and a TFA of .270 sq. inches. Landmark WELLPLAN 181 Chapter 4: Hydraulics Analysis Power Per Area Plot Use this plot to determine the power per area through the bit for a range of flow rates and varied total flow area (TFA). The following steps can be used to determine the TFA, and pump rate required to maximize bit power per area. 1. Look at the plot and determine the pump rate (x axis) corresponding to the TFA in the legend. 2. Determine the Power/Area (right side Y axis) that corresponds to the pump rate determined in Step 1. If the pumps you are using are not capable of producing this pump rate, use the maximum pump rate the pumps can produce. The pump rate begins at zero and increases until the flow rate results in parasitic pressure losses equal to 100% of the total system pressure loss. (Essentially this case results in zero pressure loss at the bit.) The power per area is calculated by first determining the pressure loss through the bit. Pressure loss calculations are based on the rheological model selected on the Fluid Editor, and assume the total system pressure loss is equal to the maximum pump pressure entered on the Pump Limits Dialog. Based on the total system pressure loss, as well as the workstring, fluid, and wellbore information entered into the String Editor, Fluid Editor, and Wellbore Editor, we can determine the pressure loss at the bit. Knowing the pressure loss at the bit, and the flow rate the TFA can be calculated. From this, the power per area of the bit can be determined. 182 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Read maximum power per area and corresponding pump rate from plot Read the TFA for the maximum power/area in the legend. Using this TFA, read the pump rate. Use this pump rate to read the power/area. Impact Force Plot Use this plot to determine the impact force of the fluid through the bit for a range of flow rates and varied total flow area (TFA). The following steps can be used to determine the TFA, and pump rate required to maximize the impact force at the bit. 1. Look at the plot and determine the pump rate (x axis) corresponding to the TFA in the legend. 2. Determine the Power/Area (right side Y axis) that corresponds to the pump rate determined in Step 1. If the pumps you are using are not capable of producing this pump rate, use the maximum pump rate the pumps can produce. The pump rate begins at zero and increases until the flow rate results in parasitic pressure losses equal to 100% of the total system pressure loss. (Essentially this case results in zero pressure loss at the bit.) The impact force is calculated by first determining the pressure loss through the bit. Pressure loss calculations are based on the rheological model selected on the Fluid Editor, and assume the total system pressure loss is equal to the maximum pump pressure entered on the Pump Limits Dialog. Based on the total system pressure loss, as well as the Landmark WELLPLAN 183 Chapter 4: Hydraulics Analysis workstring, fluid, and wellbore information entered into the String Editor, Fluid Editor, and Wellbore Editor, we can determine the pressure loss at the bit. Knowing the pressure loss at the bit, and the flow rate the TFA can be calculated. From this, the impact force at the bit can be determined. Read maximum impact force and corresponding pump rate from plot using the TFA in the legend. Read the TFA for the maximum power/area in the legend. Using this TFA, read the pump rate. Use this pump rate to read the power/area. Power Plot Use this plot to determine the power of the fluid through the bit for a range of flow rates and varied total flow area (TFA). The following steps can be used to determine the TFA, and pump rate required to maximize power at the bit. 1. Look at the plot and determine the pump rate (x axis) corresponding to the TFA in the legend. 2. Determine the Power (right side Y axis) that corresponds to the pump rate determined in Step 1. If the pumps you are using are not capable of producing this pump rate, use the maximum pump rate the pumps can produce. 184 WELLPLAN Landmark Chapter 4: Hydraulics Analysis The pump rate begins at zero and increases until the flow rate results in parasitic pressure losses equal to 100% of the total system pressure loss. (Essentially this case results in zero pressure loss at the bit.) The power at the bit is calculated by first determining the pressure loss through the bit. Pressure loss calculations are based on the rheological model selected on the Fluid Editor, and assume the total system pressure loss is equal to the maximum pump pressure entered on the Pump Limits Dialog. Based on the total system pressure loss, as well as the workstring, fluid, and wellbore information entered into the String Editor, Fluid Editor, and Wellbore Editor, we can determine the pressure loss at the bit. Knowing the pressure loss at the bit, and the flow rate the TFA can be calculated. From this, the power at the bit can be determined. For any given flowrate, the parasitic pressure loss plus the bit pressure loss is equal to total system pressure loss. Using the TFA in the legend, read the flowrate. Use this flowrate to determine the maximum bit power. Pressure Loss Plot Use this plot to determine the pressure loss through the bit for a range of flow rates and varied total flow area (TFA). The following steps can be used to determine the TFA, and pump rate required to achieve a certain pressure loss at the bit. 1. Look at the plot and determine the pump rate (x axis) corresponding to the desired pressure loss at the bit (left side Y axis). 2. Determine the TFA (right side Y axis) that corresponds to the pump rate determined in Step 1. Landmark WELLPLAN 185 Chapter 4: Hydraulics Analysis The pump rate begins at zero and increases until the flow rate results in parasitic pressure losses equal to 100% of the total system pressure loss. (Essentially this case results in zero pressure loss at the bit.) On this particular plot, the combined pressure loss through the bit plus the parasitic pressure loss should equal the total system pressure loss. The first step in this analysis is determining the pressure loss through the bit. Pressure loss calculations are based on the rheological model selected on the Fluid Editor, and assume the total system pressure loss is equal to the maximum pump pressure entered on the Pump Limits Dialog. Based on the total system pressure loss, as well as the workstring, fluid, and wellbore information entered into the String Editor, Fluid Editor, and Wellbore Editor, we can determine the pressure loss at the bit. Knowing the pressure loss at the bit, and the flow rate the TFA can be calculated. For any flowrate the parasitic pressure loss plus bit pressure losses equal the total system pressure loss Using the desired bit pressure loss, read the required flowrate and TFA. Or, use the TFA and read the required flowrate and pressure loss. Power vs. Impact Force Plot Use this plot to determine the maximum impact force, or bit power per area for a range of flow rates. 1. Look at the plot and determine the pump rate (x axis) corresponding to the maximum impact force, or bit power per area. 2. Read the corresponding impact force or bit power per area from the other curve on the plot. 186 WELLPLAN Landmark Chapter 4: Hydraulics Analysis The pump rate begins at zero and increases until the flow rate results in parasitic pressure losses equal to 100% of the total system pressure loss. (Essentially this case results in zero pressure loss at the bit.) The first step in this analysis is determining the pressure loss through the bit. Pressure loss calculations are based on the rheological model selected on the Fluid Editor, and assume the total system pressure loss is equal to the maximum pump pressure entered on the Pump Limits Dialog. Based on the total system pressure loss, as well as the workstring, fluid, and wellbore information entered into the String Editor, Fluid Editor, and Wellbore Editor, we can determine the pressure loss at the bit. Knowing the pressure loss at the bit, and the flow rate the TFA can be calculated. From this information, the impact force or bit power per are can be calculated. Read maximum impact force and corresponding bit power/area and pump rate Read maximum bit power/area and corresponding impact force and pump rate Landmark WELLPLAN 187 Chapter 4: Hydraulics Analysis Using Optimization Planning Analysis Mode The Hydraulics module offers three different methods for optimizing hydraulics. Optimization Planning is one of these methods, and Graphical Analysis and Optimization Well Site are the other two. The optimization methods available in Optimization Planning include: maximum nozzle velocity, maximum impact force, maximum hydraulic horsepower, and percent pressure loss at the bit. Using this analysis mode, the flowrate and nozzle configuration will be determined to achieve optimization with respect to one of the following methods: • maximum hydraulic horsepower • maximum jet impact force • maximum nozzle velocity • percent system pressure loss at the bit The flowrate and nozzles are calculated to fully use the available pump pressure. Pump pressure is considered to be the sum of parasitic losses (losses in the work string, annulus and in the surface lines) and the pressure drop over the bit and is equal to the maximum pump pressure. After the true optimum flowrate is determined, it may be increased slightly to utilize all of the available pump pressure. You can specify a Minimum Annular Velocity that will serve as a lower boundary for the flowrate. At no point in the annulus will the flowrate be lower than the specified minimum flowrate. The minimum annular velocity will occur in the widest annulus section. Imposing this rule on the optimization may result in a flowrate that does not generate the optimum bit hydraulics. You can also specify that turbulence in the annulus is not allowed, thus putting a limit on the maximum flowrate. Specifying that turbulence is not allowed always limits the calculated flowrate. Even if the flowrate is less than the true optimum or if it forces a velocity that is less than the specified Minimum Annular Velocity.. Imposing this rule on the optimization may result in a flowrate that does not generate the optimum bit hydraulics. The calculation determines the nozzle sizes based on the number of nozzles specified that will as closely as possible provide the required TFA. You can restrict the freedom in nozzle selection by specifying a 188 WELLPLAN Landmark Chapter 4: Hydraulics Analysis non-zero value for Minimum Nozzle Size or by specifying another number of nozzles. The final TFA may not be the exact optimal TFA after the nozzle configuration is determined. As discussed, the result of the calculations (flowrate and nozzles) may not necessarily match the optimum solution, but may be restricted by the imposed limitations. To remove all restrictions that you have control over, you may: • Check the Allow Turbulence in the Annulus box. • Specify the Minimum Annular Velocity to be zero. • Specify the Minimum Nozzle Size to be zero. Selecting Optimization Planning Analysis Select Optimization Planning from the drop down list. Entering Case Data The Optimization Planning analysis mode uses the well data entered on the Case Menu, and the analysis data entered on the Parameter Menu. For discussion on the Case Menu items that are common to all WELLPLAN modules, please refer to the Basics chapter of this manual. The common Case Menu options include: the General, Offshore, Wellbore Editor, String Editor, Fluid Editor, and Deviation Menu. Specify Circulating System Equipment You can use the Case →Circulating System tabs to specify the surface equipment configuration, maximum working pressure, and mud pump information. Refer to the Pressure: Pump Rate Range analysis mode for a detailed description of the Circulating System Tabs. Landmark WELLPLAN 189 Chapter 4: Hydraulics Analysis Specify Solution Constraints Enter data in the Input section of the Parameter →Solution Constraints dialog box, and a summary of the results will be displayed in the Quick Look section. Results displayed in the Quick Look section indicate the pump rate and nozzle configuration required to optimize hydraulics based on several optimization methods, including: Impact Force, Hydraulic Horsepower, Nozzle Velocity and Percent Pressure Loss at Bit. The Minimum Annular Velocity is used as a lower boundary for the flowrate. At no point in the annulus will the flowrate be lower than the specified minimum annular velocity. The minimum annular velocity will occur in the widest annulus section. You can specify the number and minimum size of nozzles (maximum of four nozzles sizes) that you want to use during the hydraulics optimization. The calculations attempt to determine a combination of nozzle sizes that match as closely as possible the calculated required TFA. To minimize the restrictions on nozzle selection, specify zero for the Minimum Nozzle Size. 190 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Input section Minimum annular velocity occurs in widest annular section Click to default pump data from Circulating System- Mud Pumps Tab Check to include tool joint pressure losses Check to allow turbulent flow Quick Look (results) section Use this slider control to specify the minimum annular velocity instead of entering a value in the Minimum Annular Velocity field located above this slider and at the top of this dialog. The value you define with this control is displayed in both fields. Set ECD Calculation Depths In the Parameter →ECD Depths dialog, enter up to five measured depths you would like ECD (equivalent circulating density) calculated. ECD may be calculated at any depth. Commonly ECD is calculated at the last casing shoe. The ECD of the mud is the mud weight that would exert the circulating pressures under static conditions at the specified depth. For more detail, refer to the on-line help or to the Pressure:Pump Rate Range analysis mode discussion in this chapter. Analyzing Results Report Options The Report Options Dialog is used to specify what additional information will be included on the report. Using this dialog, you can Landmark WELLPLAN 191 Chapter 4: Hydraulics Analysis include or exclude much of the information defining the case you are analyzing. Refer to the Pressure: Pump Rate Range analysis mode discussion for more detail. Reports There are several analysis reports available, including: l Maximum Nozzle Velocity Report l Maximum HHP Report l Maximum Impact Force Report l % Pressure Loss at Bit Report Use these reports for a detailed view of the Quick Look results. These reports contain the results of optimizing hydraulics based on maximum nozzle velocity. Each report contains: • The flowrate to maximize nozzle velocity, HHP, impact force, or the flowrate to achieve the specified pressure loss at the bit. • The nozzle configuration to result in the required flowrate. • Calculations using the optimal flowrate for Hydraulic Horsepower/ bit area, Hydraulic Horsepower, Impact Force, and Nozzle Velocity. • ECD’s at the depths specified on the ECD Depths Dialog. • Calculated pressure losses for the system, workstring, annulus and bit. l Tabular information for a range of bit depths including: workstring OD, hole ID, fluid velocity, critical velocity, and flow regime. The calculations use the mud information input on the Fluid Editor and determines annular volumes based on data input on the String Editor and the Wellbore Editor. Analysis constraints are specified on the Solution Constraints Dialog. 192 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Using Optimization Well Site Analysis Mode The Hydraulics module offers three different methods for optimizing hydraulics. Optimization Well Site is one of these methods, and Graphical Analysis and Optimization Planning are the other two. Optimization Well Site is based on Scott’s method for determining bit nozzle size using actual recorded rig circulating pressures. Refer to the References section in this chapter for more information about Scott’s method. All calculations are performed using only the input parameters from the Well Site Data Dialog. The work string, wellbore, survey or fluid data entered through the Case Menu is not used. Therefore, the results will be different than the results calculated using one of the other methods. The model requires the flow rate and pressure results from a low flowrate and high flowrate system pressure test. From these results, the optimum flowrate and total flow area are determined, and maximum impact force and hydraulic horsepower are calculated. Starting Optimization Well Site Analysis Select Optimization Well Site from the drop down list. Enter Case Data The Optimization Well Site analysis mode does not use the well data entered on the Case Menu. All analysis date is entered on the Parameter →Well Site Data dialog box. Landmark WELLPLAN 193 Chapter 4: Hydraulics Analysis General Dialog is only option Enter Analysis Dialog Enter data in the Input section of the Parameter →Well Site Data dialog box, and the results will be displayed in the Quick Look section. Results displayed in the Quick Look section indicate the pump rate and nozzle configuration required to optimize hydraulics based on Impact Force, or Hydraulic Horsepower. All analysis results are displayed in Quick Look Section. All analysis date is input on this dialog. 194 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Using Weight Up Analysis Mode The weight up calculation will determine the amount of material required to increase or to lower your mud weight to a desired weight. You must specify the desired mud weight, the specific gravity of the weight adjusting additive, and the surface volume. Internal pipe and annulus volumes will be calculated based on information input for the work string, and wellbore through the Case Menu. Starting Weight Up Analysis Select Weight Up from the drop down list. Enter Case Data The Weight Up analysis mode uses the well data entered on the Case menu, and the analysis data entered on the Parameter menu. The analysis assumes that the current mud weight is specified in the Fluid Editor dialog. This analysis uses the existing workstring entered in the String Editor spreadsheet and the wellbore entered in the Wellbore Editor spreadsheet to determine volumes. For discussion on the Case menu items that are common to all WELLPLAN modules, please refer to the Basics chapter of this manual. The common Case menu options include: the General, Offshore, Wellbore Editor, String Editor, and Deviation menu. Enter Analysis Data and Calculate Data You can use the Parameter →Weight Up Data dialog to calculate the amount of weight up or dilution material required to increase or to decrease your existing mud weight to another weight. This analysis assumes that the current mud weight is specified on the Fluid Editor. Landmark WELLPLAN 195 Chapter 4: Hydraulics Analysis This analysis uses the existing workstring entered on the String Editor, and the wellbore entered on the Wellbore Editor to determine volumes. You must specify the surface volume, as this information is not entered elsewhere in the module. This volume will be added to the calculated volumes for the internal workstring, annulus, and any open hole volume below the bit to get the total system volume 196 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Using Hole Cleaning Operational Analysis Mode The Hydraulics module offers two hole cleaning analysis modes. These modes are Hole Cleaning Parametric and Hole Cleaning Operational. Both modes. Although both modes are based on the same theory, the results and usage of the modes are different. You should use the Operational analysis first to analyze your current Case. After performing the Operational analysis, you may want to study the effects of varying parameters using the Hole Cleaning Parametric analysis mode. The following discussion pertains to the Operational mode. For more information on the Parametric mode, refer to the section in this manual titled Using Hole Cleaning Parametric Analysis Mode. The operational analysis determines the percentage of cuttings in the annulus of the current active case. The cuttings concentration percentage, bed height, and minimum flow rate to avoid bed formation is determined from the current inclination, annular diameters and other Case data. Information entered on the Fluid Editor, String Editor, Survey Editor, and Wellbore Editor will be used to calculate annular volumes and hole inclination. Starting Hole Cleaning Operational Analysis Select Hole Cleaning Operational from the drop down list. Enter Case Data The Hole Cleaning Operational analysis mode uses the well data entered on the Case Menu, and the analysis data entered on the Parameter Menu. Landmark WELLPLAN 197 Chapter 4: Hydraulics Analysis For discussion on the Case Menu items that are common to all WELLPLAN modules, please refer to the Basics chapter of this manual. The common Case Menu options include: the General, Offshore, Wellbore Editor, String Editor, Fluid Editor, and Deviation Menu. Enter Analysis Data The Parameter →Transport Analysis Data dialog is used to specify the analysis parameters that will be used in the Hole Cleaning Operational analysis. Normal range is 0.1 to .25 inches Enter the specific gravity of the formation being drilled A typical estimate of the porosity of the cuttings bed is 36% Analyzing Results Plot Operational Plot This plot presents the following for each measured depth in the wellbore: • Inclination • Minimum flowrate to avoid cuttings formation • Suspended cuttings volume • Bed height 198 WELLPLAN Landmark Chapter 4: Hydraulics Analysis The bed height and cuttings volume portions of the plot are calculated using the flowrate specified on the Transport Analysis Data Dialog (Operational). The minimum flowrate, and inclinations portions of the plot are independent of the specified flowrate. If there is a bed height forming, the total cuttings volume will begin to become greater than the suspended cuttings volume in that portion of the wellbore. Also, you will notice that the bed height begins to form when the minimum flowrate to avoid bed formation for a section of the well is greater than the flowrate specified on the Transport Analysis Data Dialog (Operational). In order to avoid the formation of a cuttings bed in that portion of the well, you must increase the specified flowrate to a rate greater than the minimum flowrate to avoid bed formation. Use the Rate of Penetration slider control to specify the rate at which the formation is being drilled. This value is used to determine the amount of cuttings produced per time increment — in effect a cuttings flow rate. When you specify a value here it has the same effect as specifying a value in the Rate of Penetration field in the Transport Analysis Data dialog. The new value you specify with the slider will appear in the Rate of Penetration field the next time you open the Transport Data dialog. This analysis uses the data input on the Fluid Editor, String Editor, Survey Editor, Wellbore Editor and the Transport Analysis (Operational) Data Dialog. Landmark WELLPLAN 199 Chapter 4: Hydraulics Analysis Read each plot using the same Y axis. Rate of Penetration slider can be used to change the ROP and immediately view the results in the plots. The ROP used in the plots is specified here. Report Report Options The Report Options Dialog is used to specify what additional information will be included on the report. Using this dialog, you can include or exclude much of the information defining the case you are analyzing. Refer to the Pressure: Pump Rate Range analysis mode discussion for more detail. 200 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Operational Report The report is a tabular representation of the information available on the Operational Plot, as well as some additional information. From the report, you can determine the minimum pump rate (flow rate when a cuttings bed will begin to form). For the flow rate specified on the Transport Analysis Data Dialog (Operational), you can also determine the cuttings volume, bed height, and equivalent mud weight over the entire wellbore using the MD Calculation Interval you specify on the Transport Analysis Data Dialog (Operational). Landmark WELLPLAN 201 Chapter 4: Hydraulics Analysis Using Hole Cleaning Parametric Analysis Mode The Hydraulics module offers two hole cleaning analysis modes. These modes are Hole Cleaning Parametric and Hole Cleaning Operational. Although both modes are based on the same theory, the results and usage of the modes are different. You should use the Operational analysis first to analyze your current Case. After performing the Operational analysis, you may want to study the effects of varying parameters using the Hole Cleaning Parametric analysis mode. The following discussion pertains to the Parametric analysis mode. For more information on the Operational mode, refer to the section in this manual titled Using Hole Cleaning Operational Analysis Mode. The Parametric analysis mode does not use the information entered into the wellbore, survey or workstring editors. This mode does use the PV, YP and fluid density entered in the Fluid Editor. All other required information is entered on the Transport Analysis (Parametric) Data Dialog. This analysis mode can be used to evaluate a proposed mud scheme (PV, YP and density) for a range of flow rates and hole angles. This mode can be used to illustrate the relationship of mud carrying capacity with hole angle and flow rate. The parametric mode assumes the well has constant wellbore and string geometry (constant annulus diameter, pipe diameter, and joint diameter) and performs the hole cleaning analysis for the range of flow rates specified over the inclination range from 0 to 90 degrees. Starting Hole Cleaning Parametric Analysis Select Hole Cleaning Parametric from the drop down list. 202 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Enter Case Data The Hole Cleaning Parametric analysis mode uses only the Fluid Editor data entered on the Case Menu, and the analysis data entered on the Parameter→Transport Analysis Data dialog. Data entered on the General Dialog is for information only. For discussion on the Fluid Editor, please refer to the Basics chapter of this manual. Entering Transport Analysis Data The Parameter →Transport Analysis Data dialog is used to specify the analysis parameters that will be used in the Hole Cleaning Parametric analysis. Although this analysis uses the fluid entered on the Fluid Editor, it does not use the information entered on the String Editor or on the Wellbore Editor. Normal range is 0.1 to .25 inches Enter the porosity of the cuttings bed on the lowside of the hole. A typical estimate is 36% Defines the range of pump rates that will be analyzed Landmark WELLPLAN 203 Chapter 4: Hydraulics Analysis Analyzing Results Plots Total Volume % Plot Use this plot to estimate the percentage of the annular volume that will be filled with cuttings for a range of wellbore inclinations from zero to 90 degrees. Total volume includes cuttings suspended in the drilling fluid, and cuttings forming a bed. The parametric analysis uses only the data input on the Transport Analysis (Parametric) Data Dialog, and the fluid information input on the Fluid Editor. Separate curve for each pump rate analyzed Suspended Volume % Plot Use this plot to determine the percentage of the annular volume filled with cuttings suspended in the drilling fluid. The suspended volume does not include cuttings lying in the hole and forming a bed. This plot analyzes a range of wellbore inclination from zero to 90 degrees. The parametric analysis uses only the data input on the 204 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Transport Analysis (Parametric) Data Dialog, and the fluid information input on the Fluid Editor. Separate curve for each pump rate analyzed Min. Flowrate Plot The critical flowrate is the flowrate at which a cuttings bed will begin to form. In order to prevent cuttings from forming a bed, you should maintain a flowrate greater than the critical flowrate. This graph analyzes wellbore inclinations ranging from zero to 90 degrees. The parametric analysis uses only the data input on the Transport Analysis (Parametric) Data Dialog, and the fluid information input on the Fluid Editor. Landmark WELLPLAN 205 Chapter 4: Hydraulics Analysis Minimum pump rate to avoid cuttings bed formation for range of hole angles Bed Height Plot From this graph, you can determine the cuttings bed height in the annulus for any wellbore inclination ranging from 0 to 90 degrees. The parametric analysis uses only the data input on the Transport Analysis (Parametric) Data Dialog, and the fluid information input on the Fluid Editor. Use this plot to determine the bed height for various flowrates and hole inclinations. For example, a bed height of 1.997 inches is expected with a flowrate of 200gpm and a hole inclination of 20 degrees. 206 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Supporting Information and Calculations The calculations and information in this section are presented in alphabetical order using the calculation or topic name. The material contained in this section is intended to provide you more detailed information and calculations pertaining to many of the steps presented during the descriptions of the analysis mode methodologies. If the information in this section does not provide you the detail you require, please refer to the section titled References for additional sources of information pertaining to the topic you are interested in. Backreaming Rate (Maximum) Calculation Qcrit | DP BR max = ROP max (Qcrit | DP − Qmud ) Where: BR max = Maximum backreaming rate (ft/hr) ROP max = Maximum rate of penetration (ft/hr) Qcrit = Critical flow rate (gpm) Qmud = Mud flow rate (gpm) DC = Drill collar ID (in) DP = Drill pipe ID (in) Bingham Plastic Rheology Model Shear Stress – Shear Rate Model τ = τ y + Kγ Landmark WELLPLAN 207 Chapter 4: Hydraulics Analysis Average Velocity in Pipe 4 Q V p = 2 π D Average Velocity in Annulus 4 Q Va = 2 π DH − DP 2 Apparent Viscosity for Annulus DH 2 − DP 2 PVaa = PV + 62.674773(YP )(DH − DP ) Q Apparent Viscosity for Pipe D3 PVap = PV + 62.674773(YP ) Q Modified Reynolds Number for Annulus Ra = 1895.2796( ρ )(DH − DP ) Q aa H ( PV D 2 − D 2 P ) 208 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Modified Reynolds Number for Pipe Q R p = 1895.2796( ρ ) PV D ap Pressure Loss in Annulus If Ra > 2000 , then Pa = ( )( .0012084581 ρ .75 PV .25 Q1.75 L )( ) (DH − DP ) 1.25 (D H 2 − DP ) 2 1.75 If laminar flow, then YP .0008488263(PV )Q Pa = (.053333333) + L DH − DP 2 2 ( (D H − D P ) D H − D P 2 ) Pressure Loss in Pipe If R p > 2000 , then Pp = ( )( .0012084581 ρ .75 PV .25 Q 1.75 L )( ) D 4.75 If laminar flow, then YP .0008488263(PV )Q Pp = (.053333333) + L D D4 Landmark WELLPLAN 209 Chapter 4: Hydraulics Analysis Critical Velocity and Flow in Annulus ρ ( D H − D P )2 (2000 + PVx ) + Rc PV x + 1.066(YPx ) 2 gc 2 Rc Vca = ρ 2(DH − DP ) gc π Qca = Vca (DH − DP ) 2 4 Critical Velocity and Flow in Pipe ρ D2 (2000 + PV x ) + Rc PV x + 1.066 (YPx ) 2 gc 2 Rc Vca = ρ 2D gc π Qca = Vca D 2 4 Where: D = Pipe inside diameter (ft) DP = Pipe outside diameter (ft) DH = Annulus diameter (ft) K ( = Consistency factor lb ft sec 2 n ) Vp = Average fluid velocity for pipe (ft/sec) Va = Average fluid velocity for annulus (ft/sec) Vca = Critical velocity in annulus (ft/sec) Vcp = Critical velocity in pipe (ft/sec) 210 WELLPLAN Landmark Chapter 4: Hydraulics Analysis L = Section length of pipe or annulus (ft) P = Pressure loss in pipe or annulus lb ft 2 ( ) Q = Fluid flow rate ( ft 3 sec ) Qca = Critical flow rate in annulus ft 3 sec ( ) Qcp = Critical flow rate in pipe ft 3 sec( ) γ = Shear rate (1/sec) τ ( = Shear stress lb ft 2 ) ρ = Weight density of fluid (lbm ft 3 ) Rp = Reynolds number for pipe Ra = Reynolds number for annulus PVaa = Apparent viscosity for annulus PVap = Apparent viscosity for pipe (cp ) PV = Plastic viscosity (cp ) ( ) PV x = Plastic viscosity lb sec ft 2 = (PV 47880.26) ( YP = Yield point lb 100 ft 2 ) YPx = Yield point (lb ft 2 ) Bit Hydraulic Power Bit Hydraulic Power is calculated using the flowrate entered in the input section of the Rate Dialog. Bit Hydraulic Power is a parameter that can be used to select nozzle sizes for optimal hydraulics. Bit Hydraulic Power is not necessarily maximized when operating the pump at the maximum pump horsepower. Bit Hydraulic Power is calculated using the following equation. QPb Bit Hydraulic Power (hp) = . 1714 Landmark WELLPLAN 211 Chapter 4: Hydraulics Analysis Where: Q = Circulation rate, gpm Pb = Pressure loss across bit nozzles, psi Bit Pressure Loss Calculations Bit Pressure Loss represents the pressure loss through the bit, and is calculated as follows. ρV 2 ∆Pbit = 2C d2 g c Where: ρ = Fluid density, (lb ft 3 ) V = Fluid velocity, (ft/sec) Cd = Nozzle coefficient, .95 gc = 32.17 ( ft / sec 2 ) P = Pressure (lb ft 2 ) Derivations for PV, YP, 0-Sec Gel and Fann Data Derive PV, YP, and 0-Sec Gel from Fann Data PV = Θ 600 − Θ 300 YP = 2Θ 300 − Θ 600 0 − SecGel = Θ 3 212 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Derive Fann Data from PV, YP, and 0-Sec Gel Θ 300 = PV + YP Θ 600 = 2 PV + YP Θ 3 = 0 − SecGel ECD Calculations Ph + Pf ECD = .052( Dtvd ) Ph = Wmud Dtvd (.052 ) ∆P Pf = ∑ (∆Dmd ) ∆L Where: ECD = Equivalent circulating density, (ppg) Wmud = Fluid weight, (ppg) Ph = Hydrostatic pressure change to ECD point. (psi) Pf = Frictional pressure change to ECD point (psi) ∆P = Change in pressure per length along the annulus section (psi/ft). ∆L This is a function of the pressure loss model chosen. Dtvd = True vertical depth of point of interest, (ft) ∆Dmd = Annulus section length (ft) 0.052 = conversion constant from (ppg)(ft) to psi Landmark WELLPLAN 213 Chapter 4: Hydraulics Analysis Graphical Analysis Calculations Although the Graphical Analysis and Optimization Planning analysis modes both optimize bit hydraulics, the methods used are different. Because the methods are different, the results may also be different. Click why for more information concerning what causes the differences. The following steps outline the general procedure used to perform a Graphical Analysis. 1. A total system pressures loss is specified on the Pump Limits Dialog. 2. A maximum flow rate is determined that will cause the parasitic pressure loss to equal the total system pressure loss. (This will represent zero pressure loss through the bit, or infinite bit TFA.) 3. The increment flow rate is established as the maximum flow rate divided by 100. 4. The initial analysis flow rate is set to 0.1 gpm. 5. At the analysis flow rate, the pressure loss through the drillstring, annulus and surface equipment is calculated. These combined pressure losses are the parasitic pressure losses at this flow rate. 6. The parasitic pressure loss is subtracted from the maximum pump pressure to determine the pressure loss at the bit. 7. The pressure loss through the bit and the flow rate are used to calculate the bit TFA (total flow area). 8. The Impact Force, Nozzle Velocity, and Bit Hydraulic Power are calculated from the bit TFA, pressure loss at the bit, and the flow rate. 9. The next analysis flow rate is determined by adding the increment flow rate to the existing analysis flow rate and then steps five through nine are repeated. 10. The results are presented in several graphical formats via the Hydraulics Analysis View Menu. 214 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Hole Cleaning Methodology and Calculations The Hole Cleaning model is based on a mathematical model that predicts the critical (minimum) annular velocities/flow rates required to remove or prevent a formation of cuttings beds during a directional drilling operation. This is based on the analysis of forces acting on the cuttings and its associated dimensional groups. The model can be used to predict the critical (minimum) flow rate required to remove or prevent the formation of stationary cuttings. This model has been validated with extensive experimental data and field data. By using this model, the effects of all the major drilling variables on hole cleaning have been evaluated and the results show excellent agreement between the model predictions and all experimental and field results. The variables considered for hole cleaning analysis include • Cuttings density • Cuttings load (ROP) • Cuttings shape • Cuttings size • Deviation • Drill pipe rotation rate • Drill pipe size • Flow regime • Hole size • Mud density • Mud rheology • Mud velocity (flow rate) • Pipe eccentricity Calculations and equation coefficients to describe the inter-relationship of these variables were derived from extensive experimental testing. Landmark WELLPLAN 215 Chapter 4: Hydraulics Analysis Calculate n, K,τ y , and Reynold’s Number n= (3.32)(log10)(YP + 2 PV ) (YP + PV ) K= (PV + YP ) 511 τ y = (5.11K )n ρVa ( 2−n ) (DH − DP ) n RA = (2 3)G fa K Concentration Based on ROP in Flow Channel Co = (V D 2 1471 ) (V D ) r B 1471 + Qm 2 r B Fluid Velocity Based on Open Flow Channel 24.5Qm Va = DH − DP 2 2 Coefficient of Drag around Sphere If Re < 225 then, 22 CD = Ra else, C D = 1.5 216 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Mud carrying capacity D 4 g c ( ρ c − ρ ) = 12 CM 3 ρC D Settling Velocity in the Plug in a Mud with a Yield Stress 1 4 gDc1+ bn ( ρ c − ρ 2 − b ( 2 − n ) U sp = 1− b 3 aK b ρ c Where: a = 42 .9 − 23 . 9 n b = 1 − 0 . 33 n Angle of Inclination Correction Factor 0.66 5 C a = (sin (1.33α )) 1.33 DH Cuttings Size Correction Factor C s = 1.286 − 1.04 Dc Mud Weight Correction Factor If ( ρ < 7.7 ) then C m = 1.0 Landmark WELLPLAN 217 Chapter 4: Hydraulics Analysis else C m = 1.0 − 0.0333( ρ − 7.7 ) Critical Wall Shear Stress 2n τwc = [ag sin(∝)( ρc − ρ ) Dc ρ b / 2 ] 1+ b 2n − 2b + bn Where: a = 1.732 b = -0.744 Critical Pressure Gradient Pgc = 2τwc ro 2 rh [1− ( ) ] rh Total Cross Sectional Area of the Annulus without Cuttings Bed AA = ( π DH − DP 2 2 ) 4 144 Dimensionless Flow Rate n 1 b 2(1 + 2n) 2−( 2−n ) b rp 2 rp 2 − ( 2 − n ) b ∏ g c = ∏[8 × ] × (1 − ( ) )(1 − ( ) ] 1 rh rh (a) b 218 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Where: a = 16 b =1 Critical Flow Rate (CFR) 1 c ρgc1 / c rh ( ) c + n 2−c( 2− n) Qcrit = r h [ ∏ gc 2 1 ] ( ) Kρ c −1 Correction Factor for Cuttings Concentration C BED = 0.97 − (0.00231µ a ) Cuttings Concentration for a Stationary Bed by Volume Q C bonc = C BED 1.0 − m (1.0 − φ B )(100) Qcrit Where: Landmark WELLPLAN 219 Chapter 4: Hydraulics Analysis DB = Bit diameter DH = Annulus diameter DP = Pipe diameter DTJ = Tool joint diameter DC = Cuttings diameter τy = Mud yield stress G fa = Power law geometry factor RA = Reynolds number ρ = Fluid density ρc = Cuttings density Va = Average fluid velocity for annulus VR = Rate of penetration, ROP VCTV = Cuttings travel velocity Vso = Original slip velocity VSV = Slip velocity VCTFV = Critical transport fluid velocity VTC = Total cuttings velocity K = Consistency factor n = Flow behavior index a, b, c = Coefficients YP = Yield point PV = Plastic viscosity QC = Volumetric cuttings flow rate Qm = Volumetric mud flow rate Qcrit = Critical flow rate for bed to develop Co = Cuttings feed concentration CD = Drag coefficient Cm = Mud carrying capacity 220 WELLPLAN Landmark Chapter 4: Hydraulics Analysis CA = Angle of inclination correction factor CS = Cuttings size correction factor C mud = Mud weight correction factor C BED = Correction factor for cuttings concentration C bonc = Cuttings concentration for a stationary bed by volume U sp = Settling velocity Us = Average settling velocity in axial direction U mix = Average mixture velocity in the area open to flow α = Wellbore angle φB = Bed porosity µa = Apparent viscosity λp = Plug diameter ratio g = Gravitational coefficient r0 = Radius of which shear stress is zero rp = Radius of drill pipe rh = Radius of wellbore or casing Pgc = Critical frictional pressure gradient τ wc = Critical wall shear stress Bit Impact Force Impact force is calculated using the flow rate entered in the input section of the Rate dialog. Impact force is a parameter that can be used to select nozzle sizes for optimal hydraulics. Impact force is calculated using the following equation: ρ Im pact Force (lbf) = g VQ c Where: Landmark WELLPLAN 221 Chapter 4: Hydraulics Analysis ρ ( = Density of fluid lb ft 3 ) 3 Q = Circulation rate ( ft / s ) 2 gc = Gravitational constant, 32.17 ft sec V = Velocity through the bit (ft/sec) Nozzle Velocity Velocity is calculated using the flowrate entered in the input section of the Rate Dialog. This is not necessarily the maximum velocity that can be achieved through the bits. Nozzle velocity is a parameter that can be used to select nozzle sizes for optimal hydraulics. Velocity is calculated using the following equation. Q Nozzle Velocity (ft/sec) = 2.96A Where: Q = Circulation rate, gpm 2 A = Total flow area of bit, in Optimization Planning Calculations Although the Graphical Analysis and Optimization Planning analysis modes both optimize bit hydraulics, the methods used are different. Because the methods are different, the results may also be different. Click why for more information concerning what causes the differences. The following steps outline the general procedure used to perform a Optimization Planning. 1. Determine the optimum flow rate. 2. If the optimum flow rate is below the minimum annular velocity specified on the Solution Constraints Dialog, increase it until all 222 WELLPLAN Landmark Chapter 4: Hydraulics Analysis annulus sections have a velocity greater than, or equal to, the minimum allowed. 3. If turbulent flow is not allowed (as specified on the Solution Constraints Dialog), and any annulus section is in turbulent flow, decrease the optimum flow so that no annulus sections are in turbulent flow. This may place the optimum flow rate below the minimum annular velocity. If there is a conflict between the minimum velocity and the flow regime, the controlling factor is the flow regime. 4. Select the actual bit jets from the optimum TFA (total flow area), and the number of nozzles and minimum nozzle diameter specified on the Solution Constraints Dialog.This will almost always result in a TFA greater than the optimum. 5. If the total system pressure drop is less than the maximum pump pressure specified on the Solution Constraints Dialog, increase the flow rate to use 100% of the allowed pump pressure. If the increase will violate the annular flow regime, it is ruled that the increase is not allowed. (The flow regime is controlling.) Optimization Well Site Calculations ∆PparaL = ∆PsysL − ∆PbitL ∆PparaH = ∆PsysH − ∆PbitH ρQ H 2 ∆PbitH = 2g cC 2 A2 ρQ L 2 ∆PbitL = 2 g cC 2 A2 Landmark WELLPLAN 223 Chapter 4: Hydraulics Analysis log(∆PparaH ∆PparaL ) S= log(QH QL ) ∆PparaH ∆PparaL K= s = s QH QL ∆P = KQ s 1 ∆Pmax S QHP = K (S + 1) 1 2∆Pmax S QIF = K (S + 2 ) Calculate parasitic pressure loss for optimum power ∆PparaHP @ QHP Calculate parasitic pressure loss for impact force ∆PparaIF @ QIF Calculate pressure loss allowed for bit @ optimum flow rates ∆PbitoptHP = ∆Pmax − ∆PparaHP 224 WELLPLAN Landmark Chapter 4: Hydraulics Analysis ∆PbitoptIF = ∆Pmax − ∆PparaIF Calculate bit total flow area (TFA) for each bit pressure loss at optimum flow rates ρQHP 2 AHP = 2 g c C 2 ∆PbitopHP ρQIF 2 AIF = 2 g c C 2 ∆PbitopIF Using the maximum number of nozzles and the minimum Nozzle size, determine the number and size of the nozzles to equal the two total flow area values. Where: QL = Low flow rate, ( ft 3 sec) = High flow rate, ( ft sec ) 3 QH Q HP = Flow rate at optim um horsepower, ( ft 3 sec) = Flow rate at optim um im pact force, ( ft sec ) 3 Q IF A = Bit TFA used for the pressure tests, ( ft )2 A HP = Bit TFA for optim um power, ( ft ) 2 = Bit TFA for im pact force, ( ft ) 2 A IF ρ = Fluid weight, (lbm ft ) 3 C = Shape factor, .95 for bit Landmark WELLPLAN 225 Chapter 4: Hydraulics Analysis gc = Gravitational constant, ( ft sec 2 ) S = Power law exponent for parasitic pressure loss K = Power law coefficient for parasitic pressure loss, (lbf )( ft 2 sec ft 3 ) S ∆ Pmax = Maximum allowed total system pressure loss, lbf ( ft 2 ) ∆ Ppara = Parasitic pressure loss at specific flow rate, lbf( ft 2 ) ∆ Psys ( = Total system pressure loss at specific flow rate, lbf ft 2) ∆ PbitH = Bit pressure loss at pressure test high flow rate, (lbf ft ) 2 ∆ PbitL = Bit pressure loss at pressure test low flow rate, (lbf ft )2 ∆ PparaH = Parasitic pressure loss at pressure test high flow rate, (lbf ft 2 ) ∆ PparaL = Parasitic pressure loss at pressure test low flow rate, (lbf ft 2 ) ∆ PparaHP = Parasitic pressure loss at flow rate Q HP , (lbf ft 2 ) ∆ PparaIF = Parasitic pressure loss at flow rate Q IF , (lbf ft 2 ) Power Law Rheology Model Rheological Equation τ = Kγ n Flow Behavior Index YP + 2 PV n = 3.32192809 log YP + PV 226 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Consistency Factor YP + 2 PV K= ( (100) 1022 n ) Average Velocity in Pipe 4 Q V p = 2 π D Average Velocity in Annulus 4 Q Va = 2 π DH − DP 2 Geometry Factor for Annulus (2n + 1) n (8) n −1 G fa = 2n Geometry Factor for Pipe (3n + 1) n (8) n −1 G fp = 4n Reynolds Number for Pipe ρV p (2−n ) (D n ) Rp = g c G fp K Landmark WELLPLAN 227 Chapter 4: Hydraulics Analysis Reynolds Number for the Annulus ρV a ( 2 − n ) ( D H − D P ) n RA = g c (2 3)G fa K Critical Reynolds Number for Pipe Laminar Boundary = 3470 – 1370n Turbulent Boundary = 4270 – 1370n Critical Reynolds Number for Annulus Laminar Boundary = 3470 – 1370n Turbulent Boundary = 4270 – 1370n Friction Factor for Pipe Laminar 16 Fp = Rp Transition log(n ) + 3.93 a= 50 1.75 − log(n ) b= 7 RL = 3470 − 1370n 228 WELLPLAN Landmark Chapter 4: Hydraulics Analysis 16 ( RP − RL ) a 16 F p = + b − R RL 800 RT L Turbulent log(n ) + 3.93 a= 50 1.75 − log(n ) b= 7 a Fp = b RP Friction Factor for Annulus Laminar 24 Fa = RA Transition log(n ) + 3.93 a= 50 1.75 − log(n ) b= 7 Landmark WELLPLAN 229 Chapter 4: Hydraulics Analysis RL = 3470 − 1370n 24 ( R A − RL ) a 24 Fa = + b − R RL 800 RT L Turbulent log(n ) + 3.93 a= 50 1.75 − log(n ) b= 7 a Fa = b RA Pressure Loss in Pipe ρ 2 2 P= V p F p L gc D Pressure Loss in Annulus ρ 2 2 P= Va Fa L gc DH − DP Where: 230 WELLPLAN Landmark Chapter 4: Hydraulics Analysis D = Pipe inside diameter (ft) DP = Pipe outside diameter (ft) DH = Annulus diameter (ft) Vp = Average fluid velocity for pipe (ft/sec) Va = Average fluid velocity for annulus (ft/sec) L = Pipe or annulus section length (ft) P = Pipe or annulus pressure loss lb ft ( 2 ) Q = Fluid flow rate ( ft 3 sec ) τ = Shear stress on walls lb ft ( 2 ) n = Flow behavior index lb = Consistency factor 2 sec n K ft ρ = Fluid density (lbm ft 3 ) RP = Reynolds number for pipe RA = Reynolds number for annulus RL = Reynolds number at Laminar flow boundary Fp = Friction factor for pipe Fa = Friction factor for annulus Gp = Geometry factor for pipe Ga = Geometry factor for annulus PV = Plastic viscosity YP = Yield point gc = Acceleration due to gravity, 32.174 (ft/sec) Pressure Loss Analysis Calculations The following general analysis steps are used to determine pressure losses in the various segments of the circulating system. The annular velocity or critical velocity calculations are performed within the pressure loss calculations. 1. The first step is to Calculate PV, YP, 0-Gel and Fann Data as required. The Bingham Plastic and Power Law pressure loss Landmark WELLPLAN 231 Chapter 4: Hydraulics Analysis calculations require PV/YP data. If Fann data is input, PV/YP/0-Sec Gel can be calculated. Herschel-Bulkley requires Fann data. If Fann data not is input on the Fluid Editor, it can be calculated from PV/ YP/0-Sec Gel data. 2. Calculate work string and annular pressure losses are based on the rheological model selected using the Bingham Plastic rheology model calculations, Power Law rheology model calculations or Herschel-Bulkley rheology model calculations. 3. Calculate the bit pressure loss. 4. Calculate tool joint pressure losses, if required as specified on the Rate Dialog or the Rates Dialog. 5. Determine mud motor, or MWD pressure losses as input on the Mud Motor Catalog or the MWD Catalog. 6. Calculate the pressure losses in the surface equipment using the pipe pressure loss equations for the selected rheological model. 7. Calculate the total pressure loss by adding all pressure losses together. 8. Calculate ECD if required. Pump Power Calculations If you are using more than one pump, the maximum pump power should be calculated as follows. (HPN )(Pmin ) HPs = ∑ Pmax Where: 232 WELLPLAN Landmark Chapter 4: Hydraulics Analysis N = 1 to num ber of pum ps Pmin = M inim um pum p pressure of all m axim um pum p discharge pressure ratings for pum ps activ e in the system and the surface equipm ent. Pmax = M axim um pum p pressure rating for each pum p, 1 thru n HP s = M axim um pum p horse power for the system Pump Pressure Calculations If you have more than one active pump specified on the Circulating System, Mud Pumps Tab, the Maximum Pump Pressure will be set equal to the minimum value entered for Maximum Discharge Pressure for any of the active pumps. Shear Rate and Shear Stress Calculations Shear Stress τ .. = (0.01065)Θ Shear Rate γ = (1.70333)RPM Where: lbf τ = 2 ft 1 γ = sec Θ = Fann dial reading, (deg) RPM = Fann Speed, (rpm ) Landmark WELLPLAN 233 Chapter 4: Hydraulics Analysis Swab/Surge Calculations The WELLPLAN Swab/Surge model calculates the annulus pressures caused by the annular drilling fluid flow induced due to the movement of the string. During tripping operations, the pressures throughout the well will increase or decrease depending on whether the work string is being lowered or raised. A pressure increase due to a downward pipe movement is called a surge pressure, whereas the pressure increase due to an upward pipe movement is called the swab pressure. The swab/surge calculations do not model fluid wave propagation or consider gel strength of the mud. Ls tan d Vtrip = Ttrip If the pipe closed, then Q pipe = 0.0 If the pipe is open and the pumps off, then Aopen Aratio = (A open + Aann ) Q pipe = (Vtrip )( Aclosed − Aopen )( Aratio ) If there is a surge situation, then Q pipe is negative (up the string). If there is a swab situation, then Q pipe is positive (down the string). If the pipe is open, and the pumps are on then, Q pipe = Qrate The flow rate induced by the pipe movement is: 234 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Qinduce = Vtrip Aclosed If there is a surge situation, then Qinduce is positive (up the annulus). If there is a swab situation, then Q is negative (down the induce annulus). Qann = Qinduce + Q pipe The annular flow rate, Qann , is then used to perform frictional pressure loss calculations to determine the annulus pressure profile. If the first component is a bit then, Aopen = ATFA 2 π Aclosed = ODbit 4 If the first component is not a bit then, 2 π Aopen = ID pipe 4 2 π Aclosed = OD pipe 4 Where: Landmark WELLPLAN 235 Chapter 4: Hydraulics Analysis V trip = Trip v elocity L s tan d = Stand length V trip = Trip tim e per stand Q pipe = Pipe flow rate Q induce = Flow rate induced by pipe m ov em ent Q rate = Pum p flow rate Q ann = Annular flow rate A closed = Pipe closed area A open = Pipe open area A ratio = Ratio of pipe open area to com bined pipe and annulus op ATFA = Bit total flow area, TFA Tool Joint Pressure Loss Calculations ρKV 2 ∆P = 2 Where: ρ = F luid density V = F luid v elocity in the pipe K = T ool-joint loss coefficient as a function of the R eynolds num ber (R ) in the pipe body R = R eynold’s num ber for the pipe If R < 1000; K = 0.0 If 1000 < R <= 3000; K = (1.91) log( R ) − 5.64 236 WELLPLAN Landmark Chapter 4: Hydraulics Analysis If 3000 < R <= 13,000; K = 4.66 − (1.05 log( R )) If R > 13,000; K = 0.33 Weight Up Calculations D f − Di Va = Vi Da − D f Where: Va = Additive volume Vi = Initial volume Di = Initial density Df = Final density Da = Additive density Landmark WELLPLAN 237 Chapter 4: Hydraulics Analysis References General Lubinski, A., et. al., “Transient Pressure Surges Due to Pipe Movement in an Oil Well”, Revue de L’Institut Francais du Petrole, May – June 1977. White, F. M., “Fluid Mechanics”, McGraw Hill, Inc., 1979. Wilkinson, W.L., “Non-Newtonian Fluids”, Pergamon Press, 1960. Bingham Plastic Model Bourgoyne, A. T., Chenevert, M. E., Millheim, K. K., Young Jr., F. S. “Applied Drilling Engineering”, SPE Textbook Series: Volume 2. Coiled Tubing McCann, R. C., and Islas, C. G. “Frictional Pressure Loss during Turbulent Flow in Coiled Tubing.” SPE 36345. Hole Cleaning Clark, R. K., Bickham, K. L. “A Mechanistic Model for Cuttings Transport.” SPE paper 28306 presented at the SPE 69th Annual Technical Conference and Exhibition, New Orleans, September 25–28. Luo, Yuejin and P. A. Bern, BP Research Centre; and D. B.Chambers, BP Exploration Co. Ltd. “Flow-Rate Predictions for Cleaning Deviated Wells.” IADC/SPE 23884. Luo, Yuejin, P. A. Bern, D. B.Chambers, BP Exploration. “Simple Charts to Determine Hole Cleaning Requirements in Deviated Wells.” IADC/SPE 27486. Peden, J. M., Heriot-Watt U., Yuejin Luo. “Settling Velocity of Various Shaped Particles in Drilling and Fracturing Fluids.” SPE/IADC 16243. 238 WELLPLAN Landmark Chapter 4: Hydraulics Analysis Rabia, H. Rig Hydraulics. Entrac Software: Newcastle, England (1989): Chapter 5. Herschel Bulkley Model “The YPL Rheology Model.” BPA Research Note PRN9303, 93085ART0027. “Improved Hydraulic Models or Flow in Pipe and Annuli Using the YPL Rheology Model.” BPA Bluebook Report F93-P-12, 93026ART0243. Optimization Well Site Scott, K.F., "A New Approach to Drilling Hydraulics", Petroleum Engineer, Sept. 1972. Power Law Model Milheim, Keith K., Amoco Production Co.; Said Sahin Tulga, DRD Corp. “Simulation of the Wellbore Hydraulics While Drilling, Including the Effects of Fluid Influxes and Losses and Pipe Washouts.” SPE 11057 (1982). Schuh, F., Engineering Essentials of Modern Drilling, Energy Publications Division of HBJ. Rheology Thermal Effects Annis, M. R. Journal of Petroleum Technology, August 1967. Chapman, A. J., Heat Transfer. McMillan Press. 1967. Combs, G. D. and Whitmire, L. D. Oil & Gas Journal, 30 September 1968. Dropkin, E. and Omerscales, S. “Heat transfer by Natural Convection by Fluid Confined by Parallel Plates.” ASME, February 1965. Hiller, K. H. Journal of Petroleum Technology, July 1963. Sorelle, J. Ardiolin, Bukley. “Mathematical Field Model Predicts Downhole Density Changes in Static Drilling Fluids.” SPE 11118. Landmark WELLPLAN 239 Chapter 4: Hydraulics Analysis Wilhite G. P. “Overall Heat Transfer Coefficients in Stem and Hot water Injection Wells.” Journal of Petroleum Technology, May 1967. Surge Swab Burkhardt, J. A. “Wellbore Pressure Surges Produced in Pipe Movement.” Journal of Petroleum Technology, June 1961. Clark, E. H. Jr. “Bottom-Hole Pressure Surges While Running Pipe.” Petroleum Engineering, January 1955. Fontenot, J. E., Clark R. K. “An Improved Method for Calculating Swab and Surge Pressures and Circulating Pressures in a Drilling Well.” SPE 4521 (1974). Schuh, F. J. “Computer Makes Surge-Pressure Calculations Useful.” Oil & Gas Journal, 3 August 1964. Tool Joint Pressure Loss Denison, Pressure Losses Inside Tool Joints Can Alter Drilling Hydraulics", E.B., Oil & Gas Journal, Sept. 26, 1977, pg. 66. Milheim, Keith, Amoco Production Co., Tulga, Sahin, DRD Corporation, Tulsa, OK., “Simulation of the Wellbore Hydraulics While Drilling, Including the Effects of Fluid Influxes and Losses and Pipe Washouts”, SPE 11057, 1982. 240 WELLPLAN Landmark Chapter 5 Well Control Analysis Well Control Analysis can be used to calculate the expected influx volume, assist with casing design in terms of shoe settings depths, and expected conditions resulting from an influx, generate kill sheets, determine maximum safe drilling depth, and maximum allowable influx volume. Well Control Analysis assumes the influx is a single, methane gas bubble. The influx density is the density of methane at the current temperature and pressure. The compressibility factor, Z, is based on the critical temperature and pressure of methane. Liquid influxes are not modeled, nor are dispersed gas influxes. Overview In this section of the course, you will become familiar with all aspects of using the Well Control module. You will also become familiar with the data presented on reports, and plots. To reinforce what you learn in the class lecture, you will have the opportunity to complete several exercises designed to prepare you for using the module outside of class. The information presented in this chapter can be used as a study guide during the course, and can also be used as a reference for future analysis. At the end of this chapter you will find the methodology used for each analysis mode. The methodology is useful for understanding data requirements, analysis results, as well as the theory used as the basis for the analysis. Supporting calculations and references for additional reading are also included in this chapter. Landmark WELLPLAN 241 Chapter 5: Well Control Analysis Well Control Analysis: An Introduction The Well Control Analysis Module can be used to calculate the expected influx volume, assist with casing design in terms of shoe settings depths to handle pressures associated with controlling an influx (kick), expected conditions resulting from an influx, generate kill sheets, determine maximum safe drilling depth, and maximum allowable influx volume. Well Control Analysis assumes the influx is a single, methane gas bubble. The influx density is the density of methane at the current temperature and pressure. The compressibility factor, Z, is based on the critical temperature and pressure of methane. Liquid influxes are not modelled, nor are dispersed gas influxes. Starting Well Control Analysis There are two ways to begin the Well Control Module. You can select Well Control from the Modules Menu, and then select the appropriate analysis mode. You can also click the Well Control Button and then select the appropriate analysis mode from the Mode drop down list. Select desired Well Control Analysis mode from Choose Well Control Analysis from the Modules Menu, or by submenu, or from Mode drop clicking the Well Control Button. down list. 242 WELLPLAN Landmark Chapter 5: Well Control Analysis Available Analysis Modes The Well Control Module has three available analysis modes. Each analysis mode will be discussed in this course. l Expected Influx Volume: Use this analysis mode to predict the volume of an influx while drilling or after pump shut down. l Kick Tolerance: Use this analysis mode to simulate the circulation of a kick while drilling, a swab kick or after the pumps have shut down. l Kill Sheet: Use this analysis to quickly generate a standpipe pressure schedule. Landmark WELLPLAN 243 Chapter 5: Well Control Analysis Using Expected Influx Volume Analysis Mode This analysis will predict the volume of an influx while drilling or after the pumps have been shut down. The calculation is a function of bottom hole pressure, crew reaction times, equipment performance (closing BOPs, etc.), drilling rate of penetration and reservoir properties. Starting Expected Influx Volume Analysis Mode Select Expected Influx Volume from drop down list. Enter Case Data As most other analysis modes, the Expected Influx Volume analysis mode uses the information entered on the Case menu. The contents of the Case menu will change depending on the Well Control analysis mode selected. The Well Control Setup tabs are only available while using a Well Control analysis mode. For discussion on the Case menu items that are common to all WELLPLAN modules, please refer to the Basics chapter of this manual. The common Case menu options include: the General, Offshore, Wellbore Editor, String Editor, Fluid Editor, and Deviation menu. Case menu options for Expected Influx Volume analysis mode. 244 WELLPLAN Landmark Chapter 5: Well Control Analysis Specify Choke and Kill Line Use For the Expected Influx Volume analysis mode, the Case →Well Control Setup dialog contains only the Choke/Kill tab. Use the Choke/Kill tab to specify choke and kill line usage, and sizes. This tab is not accessible unless the well is specified as offshore on the Case →General Dialog - Options tab and as subsea on the Case →Offshore dialog. Choke and kill line information is used to calculate pressure loss in these areas. Only on subsea wells is the pressure loss in the choke and kill lines significant. If the well is a land well, you do not need to enter data into the Choke/Kill tab to use the Expected Influx Volume analysis mode. For other Well Control analysis modes, the Well Control Setup dialog will contain additional tabs. These tabs are not applicable to the Expected Influx analysis, so these tabs are absent when using this analysis mode. Click the radio button to indicate to indicate the choke mode configuration you are using. If you are not using a kill line, do not enter the kill line ID. You only need to enter the ID of the lines in use. The Choke/Kill Line Length will default to the length of the riser (specified on the Wellbore Editor) plus the elevation specified on the General dialog. You many enter another value if you wish. Click here to indicate choke and/or kill line use. Choke/Kill line length defaults to riser length plus elevation, but you can change it. Enter ID of lines in use. Enter Temperature Profile for Well Control Analysis The Parameter →Temperature Distribution tabs are used to define the temperature profile in the well. Landmark WELLPLAN 245 Chapter 5: Well Control Analysis The Temperature Model tab is used to select the temperature model you want to use for the temperature calculations. The calculated temperatures will be used to calculate gas pressures and volumes, but will not be used to modify the density or rheology parameters of the drilling mud. The Steady State Circulation model performs a heat transfer calculation between the fluids in the annulus and the fluids in the string to determine their respective temperature profiles. This model is the most realistic temperature model offered. The Undisturbed Temperature model assumes the annulus and string temperature profiles are identical to the formation temperature profile. The data in this section of the dialog will default one time to the information displayed in the Undisturbed Temperature dialog on the Case Menu. After the initial default of data, any changes made to either the Case →Temperature Model tabs or to the Parameter →Temperature Distribution tabs will not be reflected in the other tab The Constant Temperature model assumes the mud is one temperature through the entire wellbore and string. This model is the least accurate. Steady State Circulation model is the most realistic model offered. Undisturbed Temperatures default from the Undisturbed Temperature dialog on the Case menu. The Additional tab allows you to specify abnormal temperatures if you are using the Undisturbed Temperature Model or the Steady-State Circulation Model. The Constant Temperature Model does not use additional Temperature data. 246 WELLPLAN Landmark Chapter 5: Well Control Analysis Additional temperature data is used in combination with the temperature data entered on the Temperature Distribution - Temperature Model Tab. Additional temperature data should be used to characterize a non-linear formation or seawater profile. These temperatures must be entered on a true vertical depth (TVD) basis. Intermediate temperatures are linearly interpolated between specified points. You must enter these additional temperatures in descending order. Determining Type of Kick The information on the Parameter →Kick Class Determination dialog is used to calculate the bottom hole pressures, influx volume, and kick tolerance and kick type at the moment an influx occurs. The initial mud gradient refers to the mud in the well when the kick occurred. The circulation flowrate is the pump rate during drilling prior to the influx and the kick interval gradient is the pore pressure gradient for the area of the formation that produced the kick. The Quick Look section displays the calculated kick type as determined from the bottom hole pressures. The Quick Look section also displays the circulating and static bottom hole pressures, and the calculated pressure at the depth where the kick occurred. There are three types of kicks including: a kick while drilling, a kick after pump shut down, and a swab kick. Defaults from Fluid Editor. Kick Interval Gradient defines the pore pressure Quick Look section displays the type of kick that occurred. In this case, it is a “Kick While Drilling”. Kick While Drilling This is a kick taken while drilling. In this case, the pore pressure is higher than the dynamic bottom hole pressure. Landmark WELLPLAN 247 Chapter 5: Well Control Analysis Kick After Pump Shut Down This is a kick taken after the circulation pumps have been shut down. The pore pressure is lower than the dynamic bottom hole pressure but higher than the static bottom hole pressure. Swab Kick This is a kick taken while tripping out of the hole. In this case, the pore pressure is lower than the static bottom hole pressure. Estimating Influx Volume The Parameter →Influx Volume Estimation tabs are used to specify information required to determine the volume of the influx. The volume of the influx depends on the kick detection method, reservoir properties, crew reaction times and the kick class determined using the Kick Class Determination dialog. Setup Tab The information displayed on the Setup tab is a summary of the results from the Kick Class Determination dialog. You can not edit the information displayed on this tab. The information is displayed here for information purposes. This tab will not be available if the kick is determined to be a “kick while swabbing”. This tab displays a summary of the results from the Kick Class Determination dialog. You can not edit the information displayed on this tab. Kick Detection Method Tab Use the Kick Detection Method tab to define the type of kick detection in use. You can choose from flowrate or volume variation methods. 248 WELLPLAN Landmark Chapter 5: Well Control Analysis This information will be used to help determine the influx size. This tab will not be available if the kick is determined to be a “kick while swabbing”. If you are using the Flowrate Variation method, you must enter the minimum flow difference that can be detected between the flowrate in and the flowrate out. For the Volume Variation method, you must enter the minimum increase in pit volume that can be practically detected. Because the change in volume is not instantaneous, you must also specify a Detection Time Delay. Detection time delay occurs primarily due to the performance of the shale shakers being used. Detection time is a function of flow rate, screen size, mud density, plastic viscosity and expected cuttings removal performance. Flow rate detection methods have no detection time delay because the change in flow rate is noticed immediately. Enter the minimum Flowrate or Volume Variation that can be detected. Detection Time Delay applies only to the Volume Variation method Reservoir Tab This tab is used to define reservoir properties that will be used to determine the size of the influx. This tab will not be available if the kick is determined to be a “kick while swabbing”. Landmark WELLPLAN 249 Chapter 5: Well Control Analysis Enter the total measured depth thickness of the reservoir. This is used if the kick occurs while drilling, or after pump shutdown. Enter the measured depth length of the reservoir that has been drilled. This is only used if the kick is determined to occur after pump shutdown. Reaction Times Tab This tab is used to specify crew reaction times during various events typical after taking a kick. This tab will not be available if the kick is determined to be a “kick while swabbing”. These reaction times will be used to determine influx size. You may set some of these reaction times to zero to model certain types of events. An example might be a hard shut-in. Enter the reaction times for the various activities. Analyzing Results The only results available for the Expected Influx Volume analysis model are displayed on the Influx Volume Estimation - Results Tab. There are no plots, reports, or tables that display analysis results. However, there is a Temperature Distribution plot available for viewing wellbore temperatures. 250 WELLPLAN Landmark Chapter 5: Well Control Analysis Influx Volume Estimation Results Tab This tab displays the results of the influx size estimation based on the information entered on other Influx Volume Estimation tabs. Total influx volume after detection and closing the well in Influx volume when first detected using the specified Kick Detection Method Calculated time to detect the influx Plots Temperature Distribution Plot This plot indicates the temperature profile as calculated based on the temperature model specified on the Parameter →Temperature Distribution - Temperature Model tab. If you are using the steady state circulation model, this plot will display separate curves indicating the undisturbed temperature, as well as the calculated string temperature and annular temperature. The Title Bar indicates the temperature model used. Landmark WELLPLAN 251 Chapter 5: Well Control Analysis Using Kick Tolerance Analysis Mode This analysis mode is used to simulate the circulation of a kick while drilling, a swab induced kick or a kick after the pumps have shut down. This analysis provides several plots to analyze the results. Using these plots, you can: • Determine wellbore pressures for depths of interests while circulating a kick. • Determine the maximum pressure at each point in the wellbore. • Determine the allowable influx volume based on formation breakdown pressure. • Calculate the maximum pressure for various influx sizes at several wellbore depths. • Estimate shoe setting depth based on formation breakdown gradients. • Calculate the wellbore pressures in the well assuming all mud in the well has been displaced by gas. You can select the Kick Tolerance analysis mode from the Modules Menu, or from the Mode drop down list. Choose Kick Tolerance analysis mode from Modules Menu, or from Mode drop down list. Enter Case Data As with most analysis modes, the Kick Tolerance analysis mode uses the information entered on the Case menu. Although, the contents of the Case menu will change depending on the analysis mode selected. For Kick Tolerance analysis, you must enter circulating system information, pore pressure and fracture pressure data. This information is not required for all Well Control analysis modes. 252 WELLPLAN Landmark Chapter 5: Well Control Analysis Specify Circulating System Equipment You can use the Case →Circulating System tabs to specify the surface equipment configuration, maximum working pressure, and mud pump information. These tabs were discussed in the Basics chapter of this manual. Enter Pore Pressure Data The Case →Pore Pressure spreadsheet is used to define the pore pressure profile as a function of depth. This spreadsheet was discussed in the Basics chapter of this manual. Enter Fracture Gradient Data The Case →Frac Pressure spreadsheet is used to define the fracture gradient profile as a function of depth. This spreadsheet was discussed in the Basics chapter of this manual. Specify Kill Method, Choke/Kill Line and Slow Pumps Data For the Kick Tolerance analysis mode, this dialog contains two tabs. Other Well Control analysis modes may contain different tabs on this dialog. Enter Choke/Kill Data The information entered into the Case →Well Control Setup dialog for the Expected Influx Volume analysis will continue to be used for the Kick Tolerance analysis. Since both analysis modes use the information Landmark WELLPLAN 253 Chapter 5: Well Control Analysis entered into this tab, remember that if you change the information, it will be changed for all analysis modes. Select Kill Method and Enter Operational Data The Case →Well Control Setup Operational tab is used to specify kill method, BOP and casing pressure rating, and leak off test results. You can choose to use either the Driller’s Method, or the Wait and Weight Method. If you choose to use the Driller’s Method, a message is added to the reports advising the user that the pressure data is based on the assumption it is only valid for the second circulation when the kill mud is pumped down the string to the bit. For the Wait and Weight Method, the pressure data is based on the assumption the kill mud is pumped down the string while the kick is circulated out. Select kill method Enter Kill Rate, Kick Data The information input on the Parameter →Kick Tolerance dialog will be used to simulate the circulation of an influx taken while drilling or after pump shutdown. For a swab kick, tripping the work string back to the bottom of the hole is simulated. In this scenario, a worst case situation of passing the influx bubble with the BHA is analyzed at every depth. The information presented in the Setup section of the Kick Tolerance dialog was determined based on information input on the Kick Class Determination dialog. The Kill Rate is the flowrate that will be used to circulate out the influx. 254 WELLPLAN Landmark Chapter 5: Well Control Analysis The influx volume can be determined using the Estimated Influx Volume analysis mode, or you can input another volume. The Depth of Interest is the depth in the well that you are interested in analyzing. Usually this will be a casing shoe depth. The Depth Interval to Check pertains to the Safe Drilling Depth analysis. This is the depth interval past the current measured depth that you want to analyze. Setup section is based on Kick Class Determination dialog results Kill rate to circulate out the influx Influx volume can be determined using the Estimated Influx Volume analysis mode Enter measured depth that you are interested in analyzing Analyzing Results The Kick Tolerance analysis mode has several plots that can be used to analyze the results. These plots can be used to analyze annular pressure as the influx is circulated, allowable kick volumes, safe drilling depths, as well as pressure resulting from fully evacuating the annulus and filling it with gas. The Kick Tolerance analysis also provides a schematic to view the position and size of the kick as it is circulated out. Plots Pressure at Depth Plot This plot displays how the pressure at a specified depth of interest in the annulus will vary as the kill mud is pumped into the well. This plot assumes the bit is at the string depth specified on the String Editor. You may choose one Depth of Interest on the Kick Tolerance Dialog. The plot also assumes a constant influx volume, which is specified on the same dialog. Landmark WELLPLAN 255 Chapter 5: Well Control Analysis The various peaks and valleys on the plot reflect the different annular areas that result in changing lengths of annular fluids and the impact on the pressure calculations. Depth of interest Fracture pressure at depth of interest Pore pressure at depth of interest Maximum Pressure Plot The Maximum Pressure plot depicts the annular pressures that will occur at any measured depth with an influx of constant volume in the well. Although you can determine from this plot what the maximum pressure will be at all measured depths, you can not determine when the high pressure was encountered as the influx was circulated out of the well. You may use this plot to determine casing burst service loads, or shoe setting depths. 256 WELLPLAN Landmark Chapter 5: Well Control Analysis Maximum annular pressure greater than fracture pressure Casing shoe depth Maximum annular pressure less than fracture pressure Allowable Kick Volume Plot This plot shows the maximum pressure encountered during kick circulation at a specified depth of interest for a range of influx volumes. The pore pressure and fracture pressure at the depth of interest are also displayed on the plot for reference. Curve indicates annular pressure at specified depth as a function of influx volume. Landmark WELLPLAN 257 Chapter 5: Well Control Analysis Safe Drilling Depth Plot This plot shows the maximum pressure at a depth of interest using a constant influx volume as the wellbore depth is increased using the specified depth interval past the current measured depth. You may want to use this plot to determine how far ahead you can drill with the casing shoe depth specified as the depth of interest. The plot includes pore pressure and fracture gradients to assist with determining maximum allowable pressures. Depth of interest Maximum annular pressure at depth of interest. Because this is a horizontal well, this line is straight. Formation Breakdown Gradient Plot This plot presents the maximum annular pressure, expressed as a gradient, that will occur as a result of the specified influx size. You can use this plot to determine the maximum pressure (expressed as a 258 WELLPLAN Landmark Chapter 5: Well Control Analysis gradient) that you can encounter without exceeding the formation fracture gradient. Maximum pressure Fracture gradient Full Evacuation to Gas Plot This plot shows the pressure that will occur at any measured depth in the well as a result of entirely filling the annulus with methane. You can use this plot to determine if the annular pressure resulting from fully evacuating the wellbore with methane will fracture the open hole section. Casing shoe Open hole annular pressure Landmark WELLPLAN 259 Chapter 5: Well Control Analysis Animation Schematics This is an animated simulation of the process of circulating the influx to the surface. In this animation, you can “see” the influx occurring, and then watch as the influx is circulated out of the well. Start animation by Stop animation by clicking this button clicking this button Click here to move to previous data point Click here to move to the next data point Kick in original position Frame Data The information on this screen is a numerical representation of circulating the influx. You can view a pictorial animation on the Schematic. The Frame Data provides more information that the Schematic. Using the Frame Data, you can easily view the bottom hole 260 WELLPLAN Landmark Chapter 5: Well Control Analysis pressure, choke pressure, influx volume and pressure as the kick is circulated out of the annulus. Buttons perform as in the Schematic Landmark WELLPLAN 261 Chapter 5: Well Control Analysis Using Kill Sheet Analysis Mode The Kill Sheet analysis can help pre-plan a course of action in the event of a kick. This can be very helpful, especially since taking a kick can be a very serious, and stressful time. It is recommended that as much of the information required for the Kill Sheet analysis is entered prior to taking a kick. This will significantly reduce the information that will be required to gather and input after a kick has occurred. The Kill Sheet analysis can quickly generate a standpipe pressure schedule, and a report of useful information. Select Kill Sheet from Mode drop down list. Enter Case Data The Kill Sheet analysis mode uses the fluid information entered on the Fluid Editor (Case menu). You may want to review the fluid information for accuracy. You may also want to review, or enter the Slow Pumps information on the Well Control Setup tabs. Later in this analysis, you will be required to select a pump speed from those entered on the Well Control Setup, Slow Pumps tab. Circulating System and Well Control Setup information entered in prior analysis 262 WELLPLAN Landmark Chapter 5: Well Control Analysis Enter Kill Sheet Data These tabs are used to collect information that will be used to generate a kill sheet. Enter Kick Analysis Parameters Use the Parameter →Kill Sheet Kick Parameters tab to specify analysis parameters to use in the kill sheet calculations. On this tab, you will specify the measured depth of the kick, pit gain, trip margin and shut-in drillpipe and casing pressures. This information will be used to generated the kill sheet, and pump schedule. Enter the pit gain as a result of the influx Enter the shut-in drill pipe and casing pressure after the well has been closed Enter additional pressure to be used as overkill Enter the additional mud weight needed to overcome the pressure reduction experienced while tripping out of the well Enter Mud Weight Up Data Use the Parameter→Kill Sheet Mud Weight Up tab to specify mud volumes (other than inside the string or in the annulus), and information defining the weight material and mixing capacities. This data will be used in the kill sheet generation. Landmark WELLPLAN 263 Chapter 5: Well Control Analysis Enter the specific gravity of the weighting material you will be using to weight up the mud to the kill mud weight Enter the amount of weighting material that can be mixed per unit of time. Enter Annular Volumes Use the Parameter →Kill Sheet Annulus tab to specify the annulus volumes. You can enter the volumes on this tab, or you can have this information automatically calculated from data input on the String Editor and Wellbore Editor. Click the Default from Editors button to calculate annular volumes from data input on String and Wellbore editors 264 WELLPLAN Landmark Chapter 5: Well Control Analysis Enter String Volumes Use the Parameter →Kill Sheet String tab to specify the string volumes. You can specify these directly, or you can copy them automatically from the String Editor. Click Default from Editors button to calculate volumes using data entered on the String editor Select Kill Pump Speed The Parameter →Kill Sheet Pumps tab is used to identify the slow circulation data for the pump used to kill the well. This tabbed dialog displays, in read only format, the information chosen from data entered on the Well Control Setup - Slow Pumps tab. If the pump information you want to use is not available by clicking the button, then you must enter pump information on the Slow Pumps tab first. After the pump information is entered, you may view and select the appropriate pump using this tab. Landmark WELLPLAN 265 Chapter 5: Well Control Analysis Click Select Pump/Kill Speed button to select Pump/Kill Speed from the entries on the Well Control Setup - Slow Pumps tab Analysis Results Plots The Kill Sheet plot indicates the desired stand pipe pressure as the kill mud is pumped down the string until it reaches the annulus. This plot will change based on the kill method selected. Initial circulating pressure Final circulating pressure 266 WELLPLAN Landmark Chapter 5: Well Control Analysis Reports Kill Sheet Report This report summarizes much of the input information. It also reports many additional types of information including: l Summary of weak links l Weight up requirement for kill mud and trip margin l Pump stroke schedule l Volumes and capacities The pump stroke schedule can be used in well control operations to use drillpipe pressure schedules to maintain the bottomhole pressure at the proper value. During well control operations, the bottomhole pressure must be maintained at a value slightly higher than the formation pressure during kill operations. Landmark WELLPLAN 267 Chapter 5: Well Control Analysis Analysis Mode Methodology The first section in this chapter discusses general analysis assumptions, and terminology used in the Well Control Module. The remaining sections cover one of the analysis modes available in the Well Control Analysis Module. In each section, the major analysis steps for the analysis mode are discussed. Within the analysis steps there may be a reference to a calculation. The title of the calculations are presented in italic for recognition. Many calculations apply to more than one analysis mode. To avoid duplicating information, the calculations are presented in alphabetical order in the section titled Supporting Information and Calculations. While reading through the methodology for a particular analysis mode you will notice calculation titles/names in italic. If you require more information about a particular calculation, please refer to the Supporting Information and Calculations section for additional information. General Assumptions and Terminology Initial Influx Volume Initial influx volume refers to the influx volume taken from the time a kick first develops through the time the kick has been brought under control (i.e. when the well has been shut in). In designing for the “worst case”, the initial influx volume is the maximum expected influx volume. Of course, the volume of the influx will change once well kill procedures are instigated and the circulation of the influx up the annulus begins. Naturally, the size of the initial influx volume is dependent on how quickly the kick is detected and controlled. Smaller kicks will result in lower pressures exerted within the wellbore as the kick is circulated out of the well. Designing the well to withstand the appropriate maximum initial influx volume will minimize the risk to the well. Influx Properties Assumptions The type of influx can be oil, gas, water, condensate, or any combination of these. However, WELLPLAN Well Control assumes that the influx is a single bubble of “pure” methane gas. Assuming the influx to be composed of entirely methane gas is a conservative or “worst case” assumption. Methane is the lightest gas likely to be encountered in any 268 WELLPLAN Landmark Chapter 5: Well Control Analysis great quantities. Methane gas will exhibit the fastest gas migration up the wellbore annulus because of the large difference in its density compared with the significantly heavier drilling mud. In practice, a gas influx will disperse into separate bubbles as it expands and rises through the well. WELLPLAN Well Control assume that the influx remains a single gas bubble in order to predict the worst possible pressure conditions. WELLPLAN does not model soluble gas kicks. In soluble gas kicks, the gas initially goes into solution with the drilling fluid (mud), and remains in solution until near the surface. This type of kick are difficult to detect, and are not handled by the Well Control Module. Influx Annular Volume and Height Smaller annular capacities between the work string and the wellbore will have “longer” influx lengths for a given initial influx volume. This will reduce the overall effect of the hydrostatic column on the bottom of the hole. In order to maintain a constant bottom hole pressure, higher choke pressures will be required at the surface. The height of the influx equates to the overall length of the influx in the annulus. It is affected by the annular volume and the gas compressibility (expansion). The length and location of the influx in the wellbore impacts the combined effect of the hydrostatic gas/mud column in the annulus. An influx located high in the annulus, or a large (“long”) influx will have higher associated choke pressures. Choke Pressure and Influx Position The position of the top of the influx also affects the choke pressure requirements. As the influx rises, the hydrostatic effect of the mud column above the gas influx reduces. As the influx rises in the annulus, higher choke (surface) pressures are required to maintain the bottom hole pressure. This effect is combated by allowing the gas to expand by opening the choke. A constant bottom hole pressure is required to prevent further influxes into the wellbore. Kill Methods The initial mud weight and the bottom hole pressure affect the choice of kill method. The common methods used are the “Driller’s Method” and Landmark WELLPLAN 269 Chapter 5: Well Control Analysis the “Wait and Weight Method”. Both of these methods maintain constant bottom hole pressure. The safest method is the “Wait and Weight” method which can circulate the influx out of the well and kill the well in one circulation. However, concerns about gas migration can result if the “wait” period is too long. In this situation, the “Driller’s Method” may be used instead. The “Driller’s Method” kills the well in a minimum of two circulations. The first circulation will circulate out the influx, and the second circulation will fill the wellbore with kill mud. Higher choke pressures will be required during the first circulation of the “Driller’s Method” to maintain a constant bottom hole pressure. Expected Influx Volume During the drilling of a reservoir, a “kick” is taken when the pore pressure of the formation being drilled exceeds the effective bottom hole (circulating, or hydrostatic) pressure exerted by the drilling mud. This results in formation fluids entering the well. The Expected Influx Volume analysis can be used to determine the volume of the influx. It is important to point out that the influx is assumed to be a single, methane gas bubble. The maximum size of the influx depends on several factors, including: • The pressure difference between the reservoir formation pressure and the effective bottom hole pressure. Based on this pressure difference, the Kick Classification calculations are used to determine the kick type. • The reservoir characteristics, including porosity, permeability, etc. • The rate of penetration through the reservoir which determines how much of the reservoir is exposed. • The type and accuracy of the equipment used to detect the influx (flowrate or volume change detection). • How quickly the well is shut in based on crew reaction times. The following are general steps performed during the analysis to determine the size of the influx. After you have determined the influx size, you can determine the effects a kick this size will have by using the Kick Tolerance analysis mode. 1. The first step is to determine the temperature profile in the well. You can choose from three temperature profiles on the Temperature 270 WELLPLAN Landmark Chapter 5: Well Control Analysis Distribution, Temperature Model Tab. Regardless of the temperature model chosen, any additional temperatures specified on the Temperature Distribution, Additional Tab will be incorporated into the temperature profile. a) The Steady State Circulation model is the most realistic as the effect of circulation is included in the model. Refer to Steady State Circulation Temperature Model calculations for details. b) The Undisturbed Temperatures model assumes the temperature profile of the drilling fluid to be the same as the surrounding rock formation. The profile is based on specified surface and total depth temperatures, or on a surface temperature combined with a geothermal gradient. c) The Constant Temperature model is the least realistic and assumes one temperature throughout the well. 2. The next step is to determine the type of kick that is occurring. The type of kick is determined by the pressure difference between the reservoir formation pressure specified on the Pore Pressure Dialog and the effective bottom hole pressure. The dynamic bottom hole pressures are determined by the same algorithms used by Pressure Loss Analysis calculations. The rheological model and fluid parameters that impact the analysis are specified on the Fluid Editor. WELLPLAN Well Control analysis defines three Kick Classifications, including: Kick While Drilling, Kick After Pump Shutdown, and Swab Kick. Estimated influx volumes can be determined for a “Kick While Drilling” or for “Kick After Pump Shutdown”. If the kick is determined to be a “Swab Kick”, an estimated influx volume can not be determined. Refer to Kick Classification for more information. 3. Based on the kick class, the volume of influx is calculated using either the Kick While Drilling Influx Estimation calculations, or the Kick After Pump Shut Down Influx Estimation calculations. Kick Tolerance Use this analysis mode to simulate the circulation of a kick while drilling, a swab induce kick or after the pumps have shut down. 1. The first step is to determine the temperature profile in the well. You can choose from three temperature profiles on the Temperature Landmark WELLPLAN 271 Chapter 5: Well Control Analysis Distribution-Temperature Model Tab. Regardless of the temperature model chosen, additional temperatures specified on the Temperature Distribution-Additional Tab will be incorporated into the temperature profile. a) The Steady State Circulation model is the most realistic as the effect of circulation is included in the model. Refer to Steady State Circulation Temperature Model calculations for details. b) The Undisturbed Temperatures model assumes the temperature profile of the drilling fluid to be the same as the surrounding rock formation. The profile is based on specified surface and total depth temperatures, or on a surface temperature combined with a geothermal gradient. c) The Constant Temperature model is the least realistic and assumes one temperature throughout the well. The next step is to determine the type of kick that is occurring using the Kick Classification calculations. WELLPLAN Well Control analysis defines three kick classifications, including: Kick While Drilling, Kick After Pump Shutdown, and Swab Kick. The type of kick is determined by the pressure difference between the reservoir formation pressure specified on the Pore Pressure Dialog and the effective bottom hole pressure. The dynamic bottom hole pressures are determined by the same algorithms used by Pressure Loss Analysis calculations. The rheological model and fluid parameters that impact the analysis are specified on the Fluid Editor. 2. After the kick class is determined, you can choose from several analysis related to wellbore pressures during a kick. For the kicks while drilling or kicks after pump shutdown, the Pressure Loss calculations are performed by the same method used in WELLPLAN Hydraulics. Pressure loss calculations are required for these kick types to determine the annular and choke frictional pressure losses resulting from pumping kill mud through the annulus. The following analyses are available. • Pressure at Depth: This analysis determines the pressure at a specified depth as well as the volume of kill mud pumped. This analysis is not available for Swab Kicks because this type of kick is circulated without pumping kill mud. The results of this analysis are available on the Pressure at Depth Plot. To determine the volume of pumped, and the influx volume as the influx is circulated, the Influx Circulation Model for Kick While Drilling or Kick After Pump Shutdown calculations are 272 WELLPLAN Landmark Chapter 5: Well Control Analysis performed. After the volume of the influx (and therefore the height of the influx in the annulus) is known, the Pressure at Depth of Interest calculations can be performed. The analysis uses several parameters input on the Kick Tolerance Dialog, including: Kill Rate, Total Influx Volume, Depth of Interest, and Kill Mud Gradient. Total Influx Volume can be calculated using the Expected Influx Volume Analysis Mode. Fracture Gradient and Pore Pressure data at the Depth of Interest will be plotted if available. This plot can be used to determine if the pressure at the Depth of Interest will remain within the wellbore pore and fracture pressures. • Maximum Pressure: This analysis determines the maximum pressure at points along the wellbore along with the associated measured depth (from surface to maximum measured depth). The results of this analysis are available on the Maximum Pressure Plot. To determine the pressures in the well as a function of volume of pumped, and the influx volume as the influx is circulated, the Influx Circulation Model for Kick While Drilling or Kick After Pump Shutdown or Influx Circulation Model for Swab Kicks calculations are performed. The analysis used several parameters input on the Kick Tolerance Dialog, including: Kill Rate, Total Influx Volume, and Kill Mud Gradient. Total Influx Volume can be calculated using the Expected Influx Volume Analysis Mode. Fracture Gradient and Pore Pressure data at the Depth of Interest will be plotted if available, and the measured depth location of the last casing shoe.This plot can be used to determine if the pressure at any wellbore depth below the last casing shoe will remain within the wellbore pore and fracture pressures. • Allowable Kick Volume: This analysis determines the pressure for several influx volumes. The influx volume increment is calculated as the annulus volume from the kick measured depth to the measured depth of the shoe, divided by eight. The first influx volume used in the calculations is equal to the influx volume increment. Each succeeding influx volume is the last influx volume plus the influx volume increment. The analysis continues until the last influx volume fills the annulus from the kick measured depth to the measured depth of the last casing shoe. The results of this analysis are available on the Allowable Kick Volume Plot. To determine the pressures resulting from the various influx volumes, the Influx Circulation Model for Kick While Drilling or Kick After Pump Shutdown or the Influx Circulation Model for Swab Kicks calculations are performed. The analysis used several parameters input on the Kick Tolerance dialog, including: Kill Rate, Depth of Interest, and Landmark WELLPLAN 273 Chapter 5: Well Control Analysis Kill Mud Gradient. Fracture Gradient and Pore Pressure data at the Depth of Interest will be plotted if available. This plot can be used to determine if the maximum influx volume that can be taken at the current bit measured depth that will not exceed the wellbore fracture gradient at the depth of interest. • Safe Drilling Depth: This analysis determines the pressure resulting from an influx taken at several measured depths as the well is drilled past the current measured depth. The results of this analysis are available on the Safe Drilling Depth Plot. This analysis is performed by moving the bit location ahead, taking a kick and performing an Influx Circulation Model for Kick While Drilling or Kick After Pump Shutdown or Influx Circulation Model for Swab Kicks. The analysis uses several parameters input on the Kick Tolerance dialog, including: Kill Rate, Total Influx Volume, Depth Interval to Check, and Kill Mud Gradient. Total Influx Volume can be calculated using the Expected Influx Volume Analysis Mode. Fracture Gradient and Pore Pressure data at the Depth of Interest will be plotted if available. This plot can be used to determine the maximum depth where pressures related to the Total Influx Volume will remain within the wellbore pore and fracture pressures. • Formation Breakdown Gradient: This analysis determines the pressure gradient in the wellbore at depths in the wellbore between the casing shoe measured depth and the kick measured depth. Influx Circulation Model for Swab Kicks or Influx Circulation Model for Kick While Drilling or Kick After Pump Shutdown calculations are performed to determine the pressures. The results of this analysis are available on the Formation Breakdown Gradient Plot. This plot can be used to determine if the pressure gradient at any location in the wellbore below the casing shoe will be outside the safety zone between the wellbore pore and fracture pressure gradients. The analysis the Kill Rate, Total Influx Volume, and Kill Mud Gradient parameters input on the Kick Tolerance dialog. Total Influx Volume can be calculated using the Expected Influx Volume Analysis Mode. In addition to the measured depth location of the last casing shoe, Fracture Gradient and Pore Pressure data will be plotted if available. This plot can be used to determine if the pressure gradient at any location in the wellbore below the casing shoe will be outside the safety zone between the wellbore pore and fracture pressure gradients. • Full Evacuation to Gas: This analysis determines the pressure in the wellbore assuming the entire wellbore annulus is filled with methane gas. The pressure in the wellbore is due to the 274 WELLPLAN Landmark Chapter 5: Well Control Analysis hydrostatic pressure of the gas as determined by the gas density resulting from the wellbore temperature at that depth. The results of this analysis are available on the Full Evacuation to Gas plot. The analysis does not any parameters input on the Kick Tolerance dialog. Fracture gradient and pore pressure data will be plotted if available. Kill Sheet Refer to the Kill Sheet Calculations. Landmark WELLPLAN 275 Chapter 5: Well Control Analysis Supporting Information and Calculations Allowable Kick Volume Calculations This analysis determines the pressure for several influx volumes. The influx volume increment is calculated as the annulus volume from the kick measured depth to the measured depth of the shoe, divided by eight. The first influx volume used in the calculations is equal to the influx volume increment. Each succeeding influx volume is the last influx volume plus the influx volume increment. The analysis continues until the last influx volume fills the annulus from the kick measured depth to the measured depth of the last casing shoe. The results of this analysis are available on the allowable kick volume plot. To determine the pressures resulting from the various influx volumes, the Influx Circulation Model for Kick While Drilling or Kick After Pump Shutdown or the Influx Circulation Model for Swab Kicks calculations are performed. The analysis uses several parameters input on the Kick Tolerance Dialog, including: Kill Rate, Depth of Interest, and Kill Mud Gradient. Fracture Gradient and Pore Pressure data at the Depth of Interest will be plotted if available. This plot can be used to determine if the maximum influx volume that can be taken at the current bit measured depth that will not exceed the wellbore fracture gradient at the depth of interest. Estimated Influx Volume and Flow Rate Calculations The influx model is: kt tD = φµcRw2 276 WELLPLAN Landmark Chapter 5: Well Control Analysis If (t D > 10 ) then, t 4πhk∆P V = D ln(t D ) µ 1 1 4πhk∆P Q = − 2 ln (t D ) ln (t D ) µ else 2 t D 1 1.5 t D ( ) 2 V = t D + + 0.5 t D + 0.5 2πRw2 hφc π 2 6π 16 1 t 0.5 t 2πhk∆P Q = 0.5 0.5 − D 0.5 + 0.5 + D tD π 4π 8 µ Refer to the Viscosity And Compressibility Of Methane calculations. Where: V ( ) = Influx v olum e, m 3 = Flow rate, (m s ) 3 Q tD = Dim ensionless tim e factor k ( ) = Perm eability, m 2 t = Tim e, one tim e step is 5 seconds, (sec) φ = Porosity µ ( = Gas v iscosity, Nsm 2 ) ∆P = Pressure difference between annulus fluid and form atio h = Height of penetration into form ation, (m ) m2 c = Gas com pressibility, N Rw = Annulus radius (m ) Landmark WELLPLAN 277 Chapter 5: Well Control Analysis Gas Compressibility T Tr = Tc P Pr = Pc Pr A = Ωa 2.5 Tr .. Pr B = Ωb Tr C1 = − AB ( C2 = A − B 2 − B ) q = −(C 2 − 0.333333) C r = − C1 + 2 − 0.0740740 3 ( t = 27.0 ∗ r 2 − 4.0q 3 ) 278 WELLPLAN Landmark Chapter 5: Well Control Analysis If (t>0) If (q>0) 3 1 .5 r Φ = a cosh ∗ q 2 2 Z = ( q ) cosh Φ3 + 0.333333 3 If (q<0) 3 1 .5 r Φ = a sinh ∗ − q 2 2 Z = ( ) Φ − q sinh + 0 .333333 3 3 If (q=0) Z = r . 0.333333 + 0 .333333 If (t<=0) 3 1 .5 r Φ = a cos ∗ q 2 2 Z = ( q ) cos Φ3 + 0.333333 3 Where: Acosh = Inverse hyperbolic cosine Asinh = Inverse hyperbolic sine Cosh = Hyperbolic cosing Sinh = Hyperbolic sine Ωa = 0.427480233548 Ωb = 0.0866403499633 T = Gas temperature P = Gas pressure Tc = 207.98 K ° , critical temperature of methane Pc = 4601000 Pa, critical pressure of methane Z = Gas compressibility factor (Z factor) Landmark WELLPLAN 279 Chapter 5: Well Control Analysis Influx Circulation Model for Kick While Drilling or After Pump Shutdown In this circulation model, the analysis is performed in a number of discrete steps with each representing a volume of mud pumped. The basic algorithm is to pump one volume increment of mud, and then determine the location of the influx, and the influx properties such as height, volume, and density. The mass remains constant until the influx begins to exit the annulus. By comparing the change in influx volume from one step to the next, an influx expansion factor is determined. This expansion factor is used to calculate the acceleration (beyond the pump rate) of the mud flowing above the influx in the annulus. The following equations and descriptions are a simplification of the actual algorithms employed in the software. Additional complexity arises due to the arbitrary complexity of the wellbore. Over the length of an influx bubble, the annulus cross sectional area and curvature may change multiple times. The influx circulation algorithm divides each influx solution into multiple problems distributed over constant annulus cross sections. The curvature over these sections dictates the complexity of relating measured depth to true vertical depth, which is a controlling factor in the determination of influx height. The solution is further divided into sections or reasonably constant temperature and compressibility factor (Z). Determine influx volume The initial influx volume (V) is input as “Total Influx Volume” on the Kick Tolerance Dialog. This volume is calculated in the case of the Allowable Kick Volume analysis. Determine initial height of the influx The true vertical depth length (h) of the influx is determined from the survey data based on the measured depth length in the annulus occupied by the initial influx volume. Determine initial pressure The initial pressure Pk of the influx is the “Kick Interval Pressure” specified on the Kick Class Determination Dialog. 280 WELLPLAN Landmark Chapter 5: Well Control Analysis Pbot = Pk Determine the influx mass V P M = bot ( 1 − e λ ) h g c − gch λ= ZRT Determine the initial density Pbot ρ= ZRT Determine initial influx gradient G = ρg c Determine initial surface pressure Ps = Pbot − ( ρg c h ) − ( ρ dm g c hdm ) − Pfchoke Determine the mud pumped increment Vinc = (Va + Vs ) 80 Landmark WELLPLAN 281 Chapter 5: Well Control Analysis Circulate the influx out of the annulus The following calculations are repeated until the influx has been circulated out of the annulus. Pump one increment of mud and determine the new location of the bottom of the influx. The bottom of the influx will move up the annulus by the measured depth required to hold one mud increment of volume in that annulus section. Vinc MD inc = A MD bot = MD bot − prev − MD inc Determine the hydrostatic pressure of the drilling mud column below the influx. For “Wait and Weight” method, the kill mud will not enter the annulus until the total volume of mud pumped is greater than, or equal to the string volume. For the “Driller’s” method, kill mud will never enter the annulus until the influx is circulated out. Phdm = hdm ρ dm g c Phkm = hkm ρ km g c Determine the new pressure at the bottom of the influx Pbot = PK − Phdm − Phkm − Pfchoke Once the bottom of the influx is moved to its new position, determine if the last volume will place the top of the influx outside of the annulus. If the top of the influx is inside the annulus To determine the new volume and height of the influx, a new influx height is assumed. Iteration is performed until the following sets of dependent simultaneous equations converge to a solution. The mass is a constant until the influx starts to exit the annulus. 282 WELLPLAN Landmark Chapter 5: Well Control Analysis V P M = bot ( 1 − e λ ) h g c Pbot ρ= ZRT M V = ρ If the top of the influx is outside the annulus In this case, the volume and height are known. V P M = bot ( 1 − e λ ) h g c Pbot ρ= ZRT Determine the new influx gradient G = ρg c Determine the new surface pressure Ps = Pbot − ( ρg c h ) − ( ρ m g c hm ) − ( ρ km g c hkm ) − Pfchoke Refer to the Gas Compressibility and Z Factor calculations. Landmark WELLPLAN 283 Chapter 5: Well Control Analysis Where: Pbot = P ressure at bottom of influx PK = Initial kick pressure Phdm = H ydrostatic pressure of the m ud from the well bottom to the influx bottom Phkm = H ydrostatic pressure of the kill m ud from the well bottom to the influx bottom P fchoke = F rictional pressure loss through the choke and kill lines. T his is calculated using the pipe pressure loss equations for the m ud rheology m odel G = Influx pressure gradient M = M ass of influx V = V olum e of influx V a = A nnulus v olum e V s = S tring v olum e V inc = M ud pum ped v olum e increm ent h = T V D height of influx h dm = T V D height of the drilling m ud in the annulus h km = T V D height of the kill m ud in the annulus g c = G rav itational constant Z = C om pressibility factor R = G as constant T = Influx tem perature, determ ined from annular tem perature profile ρ = Influx density ρ dm = D rilling m ud density ρ km = K ill m ud density A = A nnulus cross sectional area MD inc = M easured depth increm ent MD bot = M easured depth location of the influx bottom MD i = Initial m easured depth of bit MD bot − prev = P ressure m easured depth of influx bottom Influx Circulation Model for Swab Kicks In this circulation model, mud circulation is not performed. The influx is removed in a number of discrete steps. The influx is moved to the top and exits the annulus as the string is moved up the annulus. As the bit is moved up, the bottom of the influx is always kept at the same depth as the bit. Each step is represented by a new bit location. At each depth, the influx properties, such as height, volume, and density are determined. The mass remains constant until the influx begins to exit the annulus. By comparing the change in influx volume from one step 284 WELLPLAN Landmark Chapter 5: Well Control Analysis to the next, an influx expansion factor is determined. This expansion factor is used to calculate the acceleration of the mud being pushed above the influx. The following equations and descriptions are a simplification of the actual algorithms employed in the software. Additional complexity arises due to the arbitrary complexity of the wellbore. Over the length of an influx bubble, the annulus cross sectional area and curvature may change multiple times. The influx circulation algorithm divides each influx solution into multiple problems distributed over constant annulus cross sections. The curvature over these sections dictates the complexity of relating measured depth to true vertical depth, which is a controlling factor in the determination of influx height. The solution is further divided into sections or reasonably constant temperature and compressibility factor (Z). Determine influx volume The initial influx volume (V) is input as “Total Influx Volume” on the Kick Tolerance dialog. This volume is calculated in the case of the Allowable Kick Volume analysis. Determine initial height of the influx The true vertical depth length (h) of the influx is determined from the survey data based on the measured depth length in the annulus occupied by the initial influx volume. Determine initial pressure The initial pressure Pk of the influx is the “Kick Interval Pressure” specified on the Kick Class Determination Dialog. Pbot = Pk Determine influx mass V P M = bot ( 1 − e λ ) h g c Landmark WELLPLAN 285 Chapter 5: Well Control Analysis − gch λ= ZRT Determine initial density Pbot ρ= ZRT Determine initial influx gradient G = ρg c Determine initial surface pressure Ps = Pbot − ( ρg c h ) − ( ρ dm g c hdm ) Determine the measured depth increment MDinc = MDi 80 Circulate the influx out of the annulus The following calculations are repeated until the influx has been circulated out of the annulus. Move the bit and bottom of the influx up one measured depth increment. MDbot = MDbot − prev − MDinc 286 WELLPLAN Landmark Chapter 5: Well Control Analysis Determine the hydrostatic pressure of the drilling mud column below the influx. Kill mud will not enter the annulus because kill mud is not pumped for “Swab Kicks”. Phdm = hdm ρ dm g c Determine the new pressure at the bottom of the influx. There is no choke frictional loss because mud is not being pumped. Pbot = PK − Phdm Once the bottom of the influx is moved to its new position, determine if the last volume will place the top of the influx outside of the annulus. If the top of the influx is inside the annulus: To determine the new volume and height of the influx, a new influx height is assumed. Iteration is performed until the following sets of dependent simultaneous equations converge to a solution. The mass is a constant until the influx starts to exit the annulus. V P M = bot ( 1 − e λ ) h g c Pbot ρ= ZRT M V= ρ If the top of the influx is outside the annulus: In this case, the volume and height are known. Landmark WELLPLAN 287 Chapter 5: Well Control Analysis V P M = bot ( 1 − e λ ) h g c Pbot ρ= ZRT Determine the new influx gradient. G = ρg c Determine the new surface pressure. Ps = Pbot − ( ρg c h ) − ( ρ dm g c hdm ) Refer to the Gas Compressibility and Z Factor calculations. Where: 288 WELLPLAN Landmark Chapter 5: Well Control Analysis Pbot = Pressure at bottom of influx PK = Initial kick pressure Phdm = Hydrostatic pressure of the drilling m ud from well bottom to influx bottom G = Influx pressure gradient M = M ass of influx V = Volum e of influx h = TVD height of influx h dm = TVD height of the drilling m ud in the annulus gc = G rav itational constant Z = Com pressibility factor R = G as constant T = Influx tem perature, determ ined from annular tem perature profile ρ = Influx density ρ dm = Drilling m ud density MD inc = M easured depth increm ent MD bot = M easured depth location of the influx bottom MD i = Initial m easured depth of bit MD bot − prev = Pressure m easured depth of influx bottom Kick Classification WELLPLAN Well Control analysis defines three kick classifications, including: Kick While Drilling, Kick After Pump Shutdown, and Swab Kick. Estimated influx volumes can be determined for a “Kick While Drilling” or for “Kick After Pump Shutdown”. If the kick is determined to be a “Swab Kick”, an estimated influx volume can not be determined. Kick While Drilling Pore Pressure > Dynamic BHP > Static BHP This will occur if the formation pore pressure exceeds the dynamic circulating pressure exerted by the drilling fluid. In this case, the kick is circulated out by pumping kill mud for Weight & Wait Method, or by pumping drilling mud during the first circulation of the Driller’s Method. Landmark WELLPLAN 289 Chapter 5: Well Control Analysis Kick After Pump Shutdown Dynamic BHP > Pore Pressure > Static BHP This will occur if the formation pore pressure is lower than the circulating pressure of the drilling mud, and sufficient over balance exists. However, when the pumps are shut down and the circulation stops, the hydrostatic pressure of the mud alone is insufficient to counteract the pore pressure exerted. In this case, the kick is circulated out by pumping kill mud for Weight & Wait Method, or by pumping drilling mud during the first circulation of the Driller’s Method. Swab Kick Dynamic BHP > Static BHP > Pore Pressure With the formation pore pressure lower than the hydrostatic pressure of the mud, a kick can occur through swabbing of the formation. Swabbing can occur while pulling the work string out of the hole. In this case, the annulus pressure profile is modeled by moving the string with the influx, and mud is not pumped to move the influx. The bottom of the influx is keep even with the bottom of the bit. Expected Influx calculations are not allowed. Kick After Pump Shut Down Influx Estimation The sequence of events during the inflow period is divided into three time periods. 290 WELLPLAN Landmark Chapter 5: Well Control Analysis Time Period A In this time period, indications of the kick are apparent by use of the rigs kick detection equipment on surface. The sensitivity of this equipment is a factor in how much influx is taken during this period. The Estimated Influx Volume and Flow Rate Calculations are used to determine the volume of the influx and the flow rate of the mud above the influx in the annulus at the end of Time Period A. These calculations are performed for a series of five-second-time steps until the calculated volume, or flow rate is detectable. For these calculations, the following conditions apply. a) The rate of penetration, ROP, is zero because there is no rotation. b) The flow rate is zero because the pumps are shut down. c) The pressure difference, ∆P , between the formation and the drilling fluid column is between the pore pressure and the calculated dynamic bottom hole pressure. The pressure difference is due to hydrostatic pressure of the mud column. Frictional pressure loss is not generated because the mud pumps are off. d) The height of penetrated reservoir, h, is constant based on the “Exposed Height” specified on the Influx Volume Estimation Reservoir Tab. Landmark WELLPLAN 291 Chapter 5: Well Control Analysis The values for volume of influx, V, and flowrate, Q, are calculated for each five-second-time step until the end of Period A is determined based on the following conditions related to kick detection equipment. For kicks detected by “Flowrate Variation” Perform the calculations until the calculated flowrate, Q, is greater than or equal to the magnitude of the detectable flowrate variation. For kicks detected by “Volume Variation” Perform the calculations until the calculated influx volume, V, minus the flowrate, Q, times the specified “Detection Time Delay” is greater than or equal to the magnitude of the detectable volume variation. Time Period B This time period does not apply to “Kicks After Pump Shut Down” because there is no circulation. Time Period C In this time period, the well is secured. The BOP and choke valves are made ready before the well is finally closed in. How quickly this can be achieved depends on the crew reaction times specified on the Influx Volume Estimation Reaction Times Tab. Only at this stage are further formation fluids prevented from entering the well. The initial influx volume is at a maximum. The Estimated Influx Volume and Flow Rate Calculations are used to determine the volume of the influx and the flow rate of the mud above the influx in the annulus at the end of Time Period C. These calculations are performed for a series of five-second-time steps until the accumulated time steps exceed the time span of Period C. For these calculations, the following conditions apply. a) The rate of penetration, ROP, is zero because rotation has stopped. b) The mud flow rate is zero because the pumps are stopped. c) The pressure difference, ∆P , between the formation and the drilling fluid column is between the pore pressure and the calculated dynamic bottom hole pressure. The pressure 292 WELLPLAN Landmark Chapter 5: Well Control Analysis difference is due to hydrostatic pressure of the mud column. Frictional pressure loss is not generated because the pumps are off. d) The height of penetrated reservoir, h, is now a constant value equal to “Exposed Height” specified on the Influx Volume Estimation Reservoir Tab. Results The total influx volume is the sum of the influx volumes calculated for Time Period A and Time Period C. The influx volume at the time of detection is equal to the influx volume at the end of Time Period A. The kick detection time is equal to the length Time Period A. Kick While Drilling Influx Estimation The sequence of events during the inflow period is divided into three time periods. Time Period A In this time period, indications of the kick are apparent by use of the rigs kick detection equipment on surface. The sensitivity of this equipment is a factor in how much influx is taken during this period. The Estimated Influx Volume and Flow Rate Calculations are used to determine the volume of the influx and the flow rate of the mud above Landmark WELLPLAN 293 Chapter 5: Well Control Analysis the influx in the annulus at the end of Time Period A. These calculations are performed for a series of five-second-time steps until the calculated volume, or flow rate is detectable. For these calculations, the following conditions apply. a) The rate of penetration, ROP, is set to the ROP specified on the Influx Volume Estimation - Reservoir Tab. b) The flow rate is set to the drilling flow rate. c) The pressure difference, ∆P , between the formation and the drilling fluid column is between the pore pressure and the calculated dynamic bottom hole pressure. The pressure difference is due to hydrostatic pressure of the mud column, and the frictional pressure loss in the annulus. d) The height of penetrated reservoir, h, begins at zero, and increases based on ROP and elapsed time until the time has exceeded the length of Time Period A. For each five-second- time step, h will increase by a factor of (5 ∗ ROP ) . The values for volume of influx, V, and flowrate, Q, are calculated for each five-second-time step until the end of Period A is determined based on the following conditions related to kick detection equipment. For kicks detected by “Flowrate Variation” Perform the calculations until the calculated flowrate, Q, is greater than or equal to the magnitude of the detectable flowrate variation. For kicks detected by “Volume Variation” Perform the calculations until the calculated influx volume, V, minus the flowrate, Q, times the specified “ Detection Time Delay” is greater than or equal to the magnitude of the detectable volume variation. Time Period B In this time period, the drilling is stopped, the bit is pulled off-bottom and the pumps are shut down. How quickly this can be achieved depends on the crew reaction times specified on the Influx Volume Estimation Reaction Times Tab. 294 WELLPLAN Landmark Chapter 5: Well Control Analysis The Estimated Influx Volume and Flow Rate Calculations are used to determine the volume of the influx and the flow rate of the mud above the influx in the annulus at the end of Time Period B. These calculations are performed for a series of five-second-time steps until the accumulated time steps exceed the time span of Period B. For these calculations, the following conditions apply. a) The rate of penetration, ROP, is zero because rotation has stopped. b) The flow rate is set to the drilling flow rate. c) The pressure difference, ∆P , between the formation and the drilling fluid column is between the pore pressure and the calculated dynamic bottom hole pressure. The pressure difference is due to hydrostatic pressure of the mud column, and the frictional pressure loss in the annulus. d) The height of penetrated reservoir, h, is now a constant value equal to the time spent in Period A multiplied by the ROP specified on the Influx Volume Estimation Reservoir Tab. Time Period C In this time period, the well is secured. The BOP and choke valves are made ready before the well is finally closed in. How quickly this can be achieved depends on the crew reaction times specified on the Influx Volume Estimation Reaction Times Tab. Only at this stage are further formation fluids prevented from entering the well. The initial influx volume is at a maximum. The Estimated Influx Volume and Flow Rate Calculations are used to determine the volume of the influx and the flow rate of the mud above the influx in the annulus at the end of Time Period C. These calculations are performed for a series of five-second-time steps until the accumulated time steps exceed the time span of Period C. For these calculations, the following conditions apply. a) The rate of penetration, ROP, is zero because rotation has stopped. b) The mud flow rate is zero because the pumps are stopped. c) The pressure difference, ∆P , between the formation and the drilling fluid column is between the pore pressure and the Landmark WELLPLAN 295 Chapter 5: Well Control Analysis calculated dynamic bottom hole pressure. The pressure difference is due to hydrostatic pressure of the mud column. Frictional pressure loss is not generated because the pumps are off. d) The height of penetrated reservoir, h, is now a constant value equal to the time spent in Period A multiplied by the ROP specified on the Influx Volume Estimation Reservoir Tab. Results The total influx volume is the sum of the influx volumes calculated for the three time periods. The influx volume at the time of detection is equal to the influx volume at the end of Time Period A. The kick detection time is equal to the length of Time Period A. Kill Sheet Initial Circulating Pressure PICP = PSIDP + PP + PO Final Circulating Pressure ρ PFCP = PP KM ρ DM Kill Mud Weight PSIDP ρ KM = + ρ DM DKTVD ∗ 0.052 296 WELLPLAN Landmark Chapter 5: Well Control Analysis Final Mud Weight ρ FM = ρ KM + ρ TM Kill Mud Weight Increase ρ KM = ρ KM − ρ DM PSIDP ρ KM = (0 .052 D KTVD ) Final Mud Weight Increase ∆ ρ FM = ρ FM − ρ KM ∆ ρ FM = ρ TM Kill Mud Weighting Material Required WTW = VT ρ W ( ρ KM − ρ DM ) ( ρ W − ρ KM ) Final Mud Weighting Material Required WFW = VT ρ W ( ρ FM − ρ KM ) ( ρ W − ρ FM ) Formation Pressure PF = PSIDP + PHDM Landmark WELLPLAN 297 Chapter 5: Well Control Analysis Formation Equivalent Mud Weight PF ρ FEQM = 0.052 DKTVD Leak Off Equivalent Mud Weight PLO ρ LEQM = + ρ LM 0.052 DSTVD Casing Maximum Allowed Pressure PCM = (ρ LEQM − ρ DM )DSTVD (0.052) Drill Pipe Pressure PDP = PICP − ∆PHDM + ∆PFR − POC Total Delta Frictional Pressure ρ ∆PTFR = PP KM − 1 ρ DM Delta Hydrostatic Pressure ∆PHD = ( ρ KM − ρ DM )(0.052 )( DKMTVD ) 298 WELLPLAN Landmark Chapter 5: Well Control Analysis Delta Frictional Pressure D ∆PFR = ∆PTFR KMMD D KM Overkill Pressure Correction D POC = PO KMTVD DKTVD Landmark WELLPLAN 299 Chapter 5: Well Control Analysis Where: PICP = Initial circulating pressure PSIDP = Shut in drill pipe pressure PP = Pump pressure PO = Overkill pressure PFCP = Final circulating pressure PF = Formation pressure PHDM = Hydrostatic drill mud pressure at total depth PFEQM = Formation equivalent mud weight PLO = Leak off pressure PCM = Maximum casing pressure allowed PDP = Drill pipe pressure PFR = Frictional pressure POC = Overkill pressure correction W TW = Total weight of weighting material WW = W eight of weighting material W FW = Final weight of weighting material ρ KM = Kill mud density ρ DM = Drill mud density ρ FM = Final mud density ρ TM = Trip margin density ρ LEQM = Leak off equivalent mud density ρ LM = Leak off mud density ρW = W eighting material density D KTVD = True vertical depth of kick DSTVD = True vertical depth of shoe D KM = Kill mud depth D KMTVD = True vertical depth of kill mud D KMMD = Measured depth of kill mud VT = Total mud volume 300 WELLPLAN Landmark Chapter 5: Well Control Analysis Pressure at Depth of Interest Pd = PP + ∆Pmf − ∆Pg − ∆Pmh Where: Pd = P re s s u re a t th e d e p th o f in te re s t PP = F o rm a tio n p o re p re s s u re a s s p e c if ie d b y th e “K ic k In te rv a l P re s s u re ” o n th e K ic k C la s s D e te rm in a tio n d ia lo g Pmf = F ric tio n a l p re s s u re lo s s d u e to th e m u d f lo w f ro m th e d e p th o f in te re s t to th e s u rf a c e . T h e f ric tio n a l p re s s u re lo s s e s in c lu d e th e c h o k e a n d k ill lin e p re s s u re lo s s . T h e s a m e a lg o rith m s a s u s e d b y W E L L P L A N H y d ra u lic s p e rf o rm th e f ric tio n a l p re s s u re lo s s c a lc u la tio n s . T h e s e a lg o rith m s a re b a s e d o n th e rh e o lo g y m o d e l s p e c if ie d o n th e f lu id e d ito r a s w e ll a s m u d p a ra m e te rs s u c h a s P V /Y P /0 -S e c G e l o r F a n n d a ta . Pg = H y d ro s ta tic p re s s u re o f th e g a s c o lu m n f ro m th e b o tto m h o le lo c a tio n to th e d e p th o f in te re s t. P mh = H y d ro s ta tic p re s s u re o f th e m u d c o lu m n f ro m th e b o tto m h o le lo c a tio n to th e d e p th o f in te re s t. T h e s e in c lu d e a ll d rillin g m u d a n d k ill m u d . Pressure Loss Analysis The following general analysis steps are used to determine pressure losses in the various segments of the circulating system. For more information concerning the pressure loss calculations, refer to the Hydraulics Analysis section in this book. 1. The first step is to Calculate PV, YP, 0-Gel and Fann Data as required. The Bingham Plastic and Power Law pressure loss calculations require PV/YP data. If Fann data is input, PV/YP/0-Sec Gel can be calculated. Herschel-Bulkley requires Fann data. If Fann data not is input on the Fluid Editor, it can be calculated from PV/YP/0-Sec Gel data. 2. Calculate work string and annular pressure losses are based on the rheological model selected using the Bingham Plastic rheology model calculations, Power Law rheology model calculations or Herschel-Bulkley rheology model calculations. 3. Calculate the bit pressure loss. Landmark WELLPLAN 301 Chapter 5: Well Control Analysis 4. Calculate tool joint pressure losses, if required as specified on the Rate Dialog or the Rates Dialog. 5. Determine mud motor, or MWD pressure losses as input on the Mud Motor Catalog or the MWD Catalog. 6. Calculate the pressure losses in the surface equipment using the pipe pressure loss equations for the selected rheological model. 7. Calculate the total pressure loss by adding all pressure losses together. 8. Calculate ECD if required. Steady State Circulation Temperature Model To determine the temperatures along the entire wellbore length, the wellbore is divided into several sections. The following calculations are performed for each section, beginning at the annulus surface. Set initial parameter values for first section a =1 b=0 Tag = T0 302 WELLPLAN Landmark Chapter 5: Well Control Analysis Calculate constants for this section B 4 C1 = 1 + 1 + 2 A B B 4 C2 = 1 − 1 + 2 A B B 4 C 3 = 1 + 1 + 1 + 2 B B 4 C 4 = 1 + 1 − 1 + 2 B mc p A= 2πrpU p raU a B= r pU p Calculate K parameters for this section e (C2 L ) (aC 4 − 1) α= e (C1L ) (1 − aC 3 ) GL(a − 1) + GA + (a − 1)T0 + b β= (1 − aC3 )e (C1L ) Tag − T0 − βC 3 K2 = αC 3 + C 4 K 1 = αK 2 + β Estimate annulus temperature for next section Tag = K 1C 3 e (C1L ) + K 2 C 4 e (C2 L ) + GL + T0 Landmark WELLPLAN 303 Chapter 5: Well Control Analysis Calculate parameters for next section α +1 a= αC3 + C 4 (β + T0 − GA)(αC3 + C 4 ) − (βC3 + T0 )(α + 1) b= (αC3 + C 4 ) Repeat calculations for C constant parameters for this section. Repeat cycle for all sections. Calculate workstring and annulus temperatures When all depth section parameters (all K, and all C) have been determined, calculate the following annulus and workstring temperatures for all depth sections. Workstring Temperature TP = K 1e C1L + K 2 e C2 L + To + GL − GA Annulus Temperature Ta = K 1C 3 e C1L + K 2 C 4 e C2 L + GL + To 304 WELLPLAN Landmark Chapter 5: Well Control Analysis Where: Tp = Workstring temperature at depth L, (K) Ta = Annulus temperature at depth L, (K) Tag = Estimate annulus temperature at depth L, (K) To = Flow line mud temperature, (K) G = Geothermal gradient based on temperature data input on Undisturbed Temperature Tabs ,or is interpolated using the data from the Undisturbed Temperature, Additional ( Tab . Km −1 ) = Massflux, (.kgs ) −1 m cp = Heat capacity of mud, . Jkg. K ( −1 −1 ) Up = Overall heat transfer coefficient through workstring, 1680 Js m K ( −1 −2 −1 ) Ua = Overall heat transfer coefficient through annulus, 170.3 Js m K ( −1 −2 −1 ) rp = Workstring radius, (m) ra = Annulus radius, (m) L = Measured depth section length, (m) Viscosity and Compressibility of Methane Calculate the viscosity of methane at temperature and pressure P Pr = Pc T Tr = Tc ( f = A 0 + A1 Pr + A 2 Pr + A 3 Pr3 + 2 ) ( T r A 4 + A 5 Pr + A 6 Pr + A 7 Pr + 2 3 ) Tr 2 (A 8 + A 9 Pr + A10 Pr + A11 Pr3 + 2 ) Tr 3 (A 12 + A13 Pr + A14 Pr2 + A15 Pr3 ) µ base µ =ef This value is used in the Estimated Influx Calculation Tr Landmark WELLPLAN 305 Chapter 5: Well Control Analysis Calculate the compressibility of methane at temperature and pressure Pr f 1 = 0.07408 Tr3.5 0.4275 P f2 = 1.5 − 0.01501 r − 0.08664 Tr Tr Z N = f1 − f 2 Tr 0.4275 P r1 = 1.5 − 0.007506 r − 0.08664 Tr Tr r D = 3Z 2 − 2 Z + Pr 1 Tr 1 N r2 = − Pr DZ r2 c= This value is used in the Estimated Influx Calculation Pc Use the Gas Compressibility (Z Factor) calculations. 306 WELLPLAN Landmark Chapter 5: Well Control Analysis Where: µ ( = Gas Viscosity at T and P, Nsm 2 ) c ( = Gas compressibility at T and P, m 2 N ) T = Kick temperature (deg Kelvin) P = Kick Pressure , (Pa) Tc = Critical temperature of methane at 207.98 deg Kelvin Pc = Critical pressure of methane at 4,602,000 Pa Tr = Reduced temperature Pr = Reduced pressure µ base = Base viscosity for methane, 0.016 ∗ 10 −3 cp Z = Gas compressibility factor Constants: A0 = −2.46211820 ∗ 10 −00 A1 = −2.97054714 ∗ 10 −00 A2 = −2.86264054 ∗ 10 −01 A3 = 8.05420522 ∗ 10 −03 A4 = 2..80860949 ∗ 10 −00 A5 = −3.49803305 ∗ 10 −00 A6 = 3.60373020 ∗ 10 −01 A7 = −1.04432413 ∗ 10 −02 A8 = −7.93385684 ∗ 10 −01 A9 = 1.39643306 ∗ 10 −00 A10 = −1.49144925 ∗ 10 −01 A11 = 4.41015512 ∗ 10 −03 A12 = 8.39387178 ∗ 10 −02 A13 = −1.86408848 ∗ 10 −01 A14 = 2.03367881 ∗ 10 −02 A15 = −6.09579263 ∗ 10 −04 Landmark WELLPLAN 307 Chapter 5: Well Control Analysis References General Hage, J.I., Shell Research Rijswijk, Surewaard, J.H.G., Shell Research Rijswijk, Vullinghs, P.J.J., “Application of Research in Kick Detection and Well Control”, SIPM Paper presented at the IADC European Well Control Conference, Noordwijkerhout, June 2-4, 1992. Rabia, H., “Fundamentals of Casing Design”, Graham and Trotman, 1987. Estimated Influx Volume and Flow Rate Van Everdingen, A.F. and Hurst, W., “The Application of the Laplace Transformation to Flow Problems in Reservoirs”, Trans. AIDE 186, 305-324, 1949. Gas Compressibility (Z Factor) Model Calculations Redlich, O. and Kwong, J.N.S., Chem. Rev., 44,233,(1949). Steady State Temperature Swift, S.C. and Holmes, C.S., “Calculation of Circulating Mud Temperatures”, JPT, June 1970. 308 WELLPLAN Landmark Chapter 6 Surge Analysis Surge can be used for planning and designing wells where the control of surge pressures will be important and for postmortem analysis of well problems related to pressure surges. Surge can be especially useful in deep holes, while running liners, and while reciprocating pipe during cementing operations. Overview In this section of the course, you will become familiar with all aspects of using the Surge module. You will also become familiar with the data presented on reports, and plots. To reinforce what you learn in the class, you will complete several exercises designed to prepare you for using the program outside of class. The information presented in this chapter can be used as a study guide during the course, and can also be used as a reference for future analysis. At the end of this chapter you will find the methodology used for each analysis mode. The methodology is useful for understanding data requirements, analysis results, as well as the theory used as the basis for the analysis. Supporting calculations and references for additional reading are also included in this chapter. Landmark WELLPLAN 309 Chapter 6: Surge Analysis Surge Analysis: An Introduction What is the Surge Module? The Surge module is a transient pressure model that can be used for finding surge and swab pressures throughout the wellbore caused by pipe movement. This analysis can be useful for well planning operations when surge pressures need to be controlled and when well problems occurred that were related to pressure surges. It can also be useful for critical well designs when other surge pressure calculation methods are not sufficiently accurate. Surge is based on a fully dynamic analysis of fluid flow and pipe motion. (Refer to “Supporting Information and Calculations” on page 337, and the “References” on page 346sections of this chapter for more information.) This analysis solves the full balance of mass and balance of momentum for pipe flow and annulus flow. Surge solutions consider the compressibility of the fluids, the elasticity of the system, and the dynamic motions of pipes and fluids. Also considered are surge pressures related to fluid column length below the moving pipe, compressibility of the formation, and axial elasticity of the moving string. In-hole fluid properties are adjusted to reflect the effects of pressure and temperature on the fluids. Surge uses the wellbore, fluid, survey, workstring, and other parameters specified in the Case menu options. Operational, depths of interest, and moving pipe depth parameters are specified in the Parameter menu options. The analysis results (output) can be displayed on several plots, tables, and reports, which are accessed through the View menu. What is the Difference Between a Transient and Steady-State Model? The calculation of steady-state surge pressures is much easier and faster than the calculation of transient surge pressures. The transient pressure model included in the Surge module has several features that a steady- state model does not have. These features include: l Compressibility: A transient model accounts for the compressibility and expansion of the wellbore and fluids. 310 WELLPLAN Landmark Chapter 6: Surge Analysis l Storage: Fluids entering the well do not necessarily mean that fluids are exiting the well. For example, when viscous forces are extremely high, the surge pressure will be more related to the water compression and wellbore expansion than the steady state frictional pressure drop would indicate. l Elasticity: Because the drillstring can deform, the bit speed is not necessarily the draw works speed. For high yield points, pipe elasticity reduces swab pressures to an important degree. l Inertia: Fluid movement may be started or stopped. Therefore, positive and negative pressures may be developed in the same pipe movement. For high mud weights, fluid inertia results in higher swab pressures. When Should I use the Transient Surge Model? Under what circumstances are the more complex transient pressure calculations justified? Generally, more accurate estimates for surge pressures are required when there is a small margin for error. Some specific operations when Surge is useful include: l Tripping drill strings in deep hot holes, especially while drilling below liners l Running long casing strings, especially those with low clearance l Running liners, especially for larger sizes run in holes with minimal clearance l Analyzing pressure surges due to pipe movement during cementing of long strings and liners, especially where high pressure gas zones could be effected by surge pressures l Optimizing the selection of drilling fluid densities and pipe motions for wells with narrow margins between pore pressure and fracture gradients The following examples illustrate the advantage a transient surge model can offer. l Example 1: Assume that the wellbore pressure is close to the fracture pressure at one point in the open hole section. In other sections of the well there is a healthy margin relative to the pore Landmark WELLPLAN 311 Chapter 6: Surge Analysis pressure. Using a steady state model, surge pressures would clearly need to be controlled to prevent fracture, but the swab pressures would not be a consideration. Transient analysis of swab pressures would show that rebound pressures at the end of the swab could exceed the fracture pressure and cause unexpected lost returns. l Example 2: If the bit is nearing the casing setting depth, the wellbore pressure will be close to both the fracture pressure (top of the open hole) and the pore pressure (bottom of the open hole). surge pressures when tripping in should be maintained below the fracture pressure and above the pore pressures. In this case, there is little margin for error, so the most accurate calculation is needed. l Example 3: Running low clearance liners has the potential to generate large surge pressures because of the high pressure drop in the narrow annulus between the liner and wellbore. In this case, the transient model helps by including an effect not considered in a steady-state calculations: the elasticity of the work string. Steady- state models usually assume that the liner moves at the same speed as the draw works. In this case, the resistance to movement may be so high that the liner doesn’t move at all, at least not initially. As the fluid flow develops transiently, the liner will slowly descend, almost independent of the draw works speed. 312 WELLPLAN Landmark Chapter 6: Surge Analysis Workflow q Open the Case. (File →Open Case) If you have created a new case, save the case. (File →Save As) q Enter general information about the case. (Case →General) q If this is an offshore well, enter water depth and well type. (Case →Offshore If this isn’t an offshore well, you won’t be able to access this dialog.) q Define the wellbore. (Case →Wellbore) q Define the workstring. Use the same dialog to define all workstrings (drillstrings, tubing, liners, and so forth) (Case →String) q Enter deviation (survey) data. (Case →Deviation→Survey Editor) q Define the fluids used. This can be either mud or cement. You must define the fluid rheological properties, select a rheology model, and specify the temperature. You can define as many fluids as you want. Only one fluid can be used for tripping operations. For reciprocating operations, you can specify two fluids: a wellbore fluid and a circulating fluid. You can use a different fluid with each operation you are analyzing, but you will need to calculate results each time you change the fluid. (Case →Fluid Editor) q Define the pore pressure gradients. (Case →Pore Pressure) q Define the fracture gradients. (Case →Frac Gradient) q Specify formation temperatures. (Case →Undisturbed Temperature) q Optional Step: Specify the formation properties if you know the elastic properties of the wellbore formations. This information will result in a more accurate analysis. (Case →Formation Properties) q Optional Step: Enter the properties of the set cement. The default value for elastic modulus is 3 X 106 psi. The default value for Poisson’s ratio is 0.35. (Case →Cement Properties) Landmark WELLPLAN 313 Chapter 6: Surge Analysis q Optional Step: Specify the eccentricity ratio of the annuli at different measured depths. Eccentricity reduces the pressure drop for annular flow. This information is useful for evaluating the effects of eccentricity on a vertical well. For a deviated well, the pipe is automatically assumed to be fully eccentric in the deviated sections. (Case →Eccentricity) q Specify the analysis parameters you want to use for this analysis run. These parameters apply to all operations you are analyzing. You must specify the fluid (mud or cement) in use, and one or more depths (called Moving Pipe Depths) where the bottom of the moving pipe is located during the analysis. Calculations are performed at the depths specified in these columns assuming that the bottom of the moving pipe is at these depths. (Parameter→Operations Data→Analysis Parameters tab) q Specify the depth(s) that you are interested in analyzing.(These depths are called Depth of Interest.) Typically this is the last casing shoe, and the total depth of the well (TD). Analysis results will be calculated for each of the Depths of Interest assuming the pipe is at each of the Moving Pipe Depths specified. (Parameter→Operations Data→Operations tab) q Define an operation that you want to analyze. You must enter a unique name for the operation, and specify the operation type (surge, swab, or reciprocation). (Parameter→Operations Data→Operations tab) q After you have created an operation, you must define the operation parameters. To do this, click the row number of the operation you want to define. This will highlight the operation. After the operation has been highlighted, click the Details button. You won’t be able to click the Details button until after you create and highlight the operation. (Parameter→Operations Data→Operations tab) q Define the operation details. For Surge or Swab Operations: Specify the stand length, acceleration and deceleration speeds. You must also specify if you want to optimize trip time, or use a float. (Parameter→Operations Data→Operations tab→Details button→Analysis Details tab) If you are not optimizing trip time, define the maximum speeds the workstring can move for each depth interval specified on the Analysis Depths tab. (If you are optimizing, these values will be calculated.) The depths on this dialog are defined by the Moving 314 WELLPLAN Landmark Chapter 6: Surge Analysis Pipe Depths you specified in an earlier step. (Parameter→Operations Data→Operations tab→Details Button→Analysis Depths tab) For Reciprocation Operations: Specify the acceleration and deceleration speeds. You must also specify if you want to optimize trip time. (Parameter→Operations Data→Operations tab→Details Button→Analysis Details tab) Next, define the stroke length, stroke rate, circulating fluid, and flowrate. (Parameter→Operations Data→Operations tab→Details Button→Reciprocation Data tab) q Repeat the above two steps to define as many operations as necessary. Analyzing more than two or three operations at a time can become complicated, so you may want to repeat the analysis steps rather than run one analysis with many operations. q Calculate the results. (View→Calculate) q Analyze the results. You will want to review the Surge Limit, Swab Limit, and Transient Response plots. Use the Surge and Swab Limit plots to determine if the maximum surge or swab pressures exceed the pore or fracture pressure gradients. Use the Transient Response plot to determine if the fluctuating pressures exceed the pore or fracture pressures. Sometimes a surge operation may experience pressures below pore pressure, or a swab operation will experience pressures above the fracture pressure. You will need to review the Transient Response plots to notice this. Landmark WELLPLAN 315 Chapter 6: Surge Analysis Using Surge Analysis Mode Starting Surge Analysis There are two ways to begin the Surge module: l Select Surge from the Modules menu. l Click the Surge button . Select Surge from Modules menu or click Surge button. Entering Case Data Surge analysis uses the information input on the Case menu. Entry of some of this information is discussed in the section “Entering Case Data” on page 40 of the Basics chapter of this manual. For information on using the General, Offshore, Wellbore Editor, String Editor, Deviation, Pore Pressure, Frac Pressure and Undisturbed Temperature dialogs, please refer to the Basics chapter of this manual. Case menu options specific to Surge analysis will be covered in this chapter of the manual. Case menu items specific to Surge analysis are the Formation Properties spreadsheet, Cement Properties spreadsheet, and the Eccentricity spreadsheet. 316 WELLPLAN Landmark Chapter 6: Surge Analysis Case menu options for Surge analysis Define Fluid Properties and Rheological Model Use the Case →Fluid Editor dialog to assign the rheological model and specify other basic characteristics about standard drilling muds or cement slurries. The Fluid Editor is discussed in the section “Defining Drilling Fluids” on page 50 of the Basics section of this manual. The Fluid Editor has the following two tabs while using the Surge module. l Standard Muds tab - Use this tab to specify the basic characteristics of simple or standard drilling muds. l Cement Slurries tab - Use this tab to specify basic cement slurry characteristics. Formation Properties Use Case →Formation Properties to specify the properties of the formation if you have this information available. These data are used to calculate the compressibility of the formation. If you don’t specify data in this spreadsheet, default values of 1.45 X 106 psi for Elastic Modulus, and 0.3 for Poisson’s Ratio will be used. Most of the time you will not have this information available, and the default values are sufficient. In those situations where you have information regarding the elastic properties of the wellbore material, you can use this dialog to obtain a more accurate analysis. For most formations, the Elastic Modulus ranges between 1 X 106 and 2 X 106 psi. Poisson’s Ratio ranges between 0.2 and 0.3 for most formations. Landmark WELLPLAN 317 Chapter 6: Surge Analysis Specify the top and bottom of the formation layer, the Elastic Modulus, and Poisson’s Ratio. Cement Properties Use the Case →Cement Properties dialog to specify the elastic properties of the set cement behind the casing, if you have this information available. These data help provide more accurate calculated results of the analysis. If you don’t specify the Cement Properties using this dialog, the analysis will use the formation properties input on the Case →Formation Properties dialog. Use this dialog to specify the properties of the set cement (behind the casing). Eccentricity Use Case →Eccentricity spreadsheet to specify the eccentricity ratio of the annuli at different depths. Eccentricity reduces the pressure drop for annular flow. This information is useful for evaluating the effects of eccentricity on a vertical well. For a deviated well, the pipe is automatically assumed to be fully eccentric in the deviated sections. An eccentric annulus ratio is defined by specifying the displacement from the centerline divided by the radial clearance outside the moving pipe. You need to define the eccentricity for each annular section and then its eccentric value. Define the annular section by specifying a depth in the Depth cell for the row, and then specify an eccentric value for the section. A value of zero is concentric and a value of 1 is fully eccentric. 318 WELLPLAN Landmark Chapter 6: Surge Analysis You can use the WELLPLAN Torque Drag module Position Plot to determine the position of the string in the wellbore. The position in the wellbore can be used to determine the eccentricity. Remember, you must use a stiff string analysis to be able to generate a Position plot. Check Concentric Annulus to indicate the entire string is concentric in the annulus. When this box is checked, data in the spreadsheet is not used. Enter eccentricity = 1 to indicate string positioned against the wellbore. Specifying Surge Operations and Analysis Parameters Use the two Parameter→Surge Operations Data tabs to specify: l Operation types you want to analyze and the depths at which the operation types are performed. l Moving pipe depths, and whether a wellbore fluid or cementing fluids are in use. Analysis Parameters Tab Use the Parameter→Surge Operations Data→Analysis Parameters tab to specify moving pipe depths, and the wellbore fluid or cementing fluids (muds and/or slurries) in use. Mark the Cementing check box if cementing fluids are in use. When you mark this box you will need to specify the fluids and/or slurries in use, and their upper-level depths. When this check box is unmarked, you cannot specify any slurries and fluids, and you must specify the Landmark WELLPLAN 319 Chapter 6: Surge Analysis fluid in the wellbore using the Wellbore Fluid field. The Wellbore Fluid field is disabled when this check box is marked. Specify a combined cased and open hole friction factor. Specify the fluid to be used in the analysis. The Wellbore Fluid drop-down list has the fluids defined in the Fluid Editor dialog. This option is disabled when the Cementing check box is marked. Specify the depths where the bottom of the moving pipe is located. Calculations are performed at the depths specified in these columns assuming that the bottom of the moving pipe is at these depths. These depths will be used as the Analysis Depths on the Parameter→Surge Operations→Details button→Analysis Depths tab. Specify the Operations to Analyze Use the Parameter→Surge Operations Data→Operations tab to specify the name and type of the operation(s) you want to analyze. You can also specify one or more Depths of Interest. Typically a depth of interest will be depths in the well where you are particularly interested in analyzing. Examples may include the casing shoe, or the well TD. For the depths specified in the Depths of Interest fields, complete analysis are performed for all operations listed in the Operation/Operation Type section. You can name any operation by typing a name into the Operation cell. After you have entered an operation name, you must select an operation type by clicking the cell. From the drop-down list, click an operation to associate with the name you have entered. Operation Type choices are Swab, Surge, and Reciprocation. Using this tab, you can specify multiple operations using the same operations type if you wish. For example, you can analyze two swab 320 WELLPLAN Landmark Chapter 6: Surge Analysis cases. Using the Details button, you can specify different analysis details about each swab, surge or reciprocation analysis. Keep in mind that analyzing several operations at once may become too complex. You may want to limit the analysis to two or three operations at a time. Enter Depths of Interest. Additional depths of interest taken from the depths specified on the Click the pore and frac pressure operation for spreadsheets will which you will automatically be used in specify analysis the analysis, but are not details. Then displayed here. click Details to specify the Analysis Details. Enter a name for the operation first. Then specify the Operation Type. Analysis Details Use the Analysis Details tabs to define details about the analysis you are performing. The Analysis Conditions dialog and tabs are displayed when you click the Details button on the Parameter →Operations Data →Operations tab. The tabs displayed will depend on the operation type you have selected. Analysis Conditions (for Tripping) Tab Use the Analysis Conditions tab (Parameter→Surge Operations Data→Operations tab→Details button→Analysis Conditions) to define details about conditions when tripping in and out of the hole for the operation you selected in the Parameter→Surge Operations Data→Operations tab. The criteria you specify here includes trip speeds, acceleration rates, and deceleration rates. You can also specify whether floats and optimized trip times should be included in the operation. Landmark WELLPLAN 321 Chapter 6: Surge Analysis Check the Optimize Trip Time box to calculate the maximum speed the pipe can be tripped by increasing the calculation time. Trip time is optimized by calculating the fastest times where surge and swab pressures do not exceed the input constraints for fracture pressures and pore pressures (as specified in their respective spreadsheets). When the formation limits are exceeded, the speed is reduced until the limits are satisfied. Check the Float in Pipe box to calculate the pressures assuming there is non-moving fluid above the float in the moving pipe. A float inhibits fluid from flowing up into the moving pipe. The analysis details are the same for both tripping in and out. However, you can have different operations details for each operation specified on the Parameter →Operations Data →Operations tab. Check this box to perform calculation to optimize trip time. Check this box to include a float. To optimize trip time, you must specify a maximum trip speed. Specify the linear acceleration and deceleration. Analysis Depths (for Tripping Operations) Tab Use the Analysis Depths tab to define details for complex pipe speeds for the depths of interest specified in the Parameter→Surge Operations Data→Operations tab. This tab is not available if you are analyzing reciprocation, or if you have checked the Optimize Trip Time box. Depth cells are read-only. They are populated with the values specified in the Moving Pipe Depth fields in the Parameter→Surge Operations Data→Analysis Parameters tab. Use the Pipe Speed cells to specify the speeds that the pipes are tripped in and out of the hole depending on the operation type you have selected. 322 WELLPLAN Landmark Chapter 6: Surge Analysis Depth cells are read-only. Depths are entered in the Moving Pipe Depths fields on the Parameter→Surge Operations→Analysis Parameters tab. Specify the speeds that the pipes are tripped in and out of the hole for the specified depth interval. Analysis Conditions (for Reciprocation) Tab Use the Analysis Conditions tab to define details about conditions when reciprocating if you selected reciprocation in the Parameter→Surge Operations Data→Operations tab. The criteria you specify here include acceleration rates, and deceleration rates. You can also specify whether floats should be included in the operation. You can not check the Optimize Trip Time box because this type of analysis doesn’t pertain to reciprocating. Similarly, the stand length and maximum trip time fields are also unavailable. Check the Float in Pipe box to calculate the pressures assuming there is non-moving fluid above the float in the moving pipe. A float inhibits fluid from flowing up into the moving pipe. Check this box to include a float. Specify the linear acceleration and deceleration. Landmark WELLPLAN 323 Chapter 6: Surge Analysis Reciprocation Data Tab Use the Reciprocation Data tab to define details about stroke velocity and fluid circulation for the reciprocation operation specified in the Parameter→Surge Operations Data→Operations tab. These details are defined by specifying stroke length, stroke rate, fluid type, and flow rate in the fields provided. Keep in mind when you define the velocity profile data (stroke length and rate), that if the moving pipe approaches within 20 feet of the current measured depth of the well, the analysis depth is backed off from the well bottom by 20 feet plus the length of one stroke before the reciprocation analysis begins. Also, 60 seconds of circulation is simulated before the reciprocation analysis begins to ensure that steady- state circulation is achieved. Specify the length the pipe is moved up and down for each stroke. Specify the number of strokes rates per minute. One stroke consists of an up-and-down cycle. Specify the circulation or displacement fluid to use in the analysis. The drop-down list contains the fluids defined in the Fluid Editor dialog. Calculating Results Use the View →Calculate dialog to calculate the swab, surge, and reciprocation operations defined in the Surge Operations Data dialog. The items in the dialog’s list are calculated using values you specified in the Case and Parameter menu options. You highlight the items you want calculated by clicking them. All highlighted items are calculated one after the other in the order they are listed on this dialog. Click Diagnostics if you want the input and output data files displayed during the operation calculations. The Diagnostics dialog appears with 324 WELLPLAN Landmark Chapter 6: Surge Analysis two file types that you can select for displaying and editing. These data files follow a specific format. If you want to edit them, please contact Landmark support for assistance. Click Calculate when you are ready to calculate your data. You can view the analysis results using the View menu options. Click Calculate to begin the calculations. Highlight the operations you want to analyze. Click Diagnostics to display the Diagnostics dialog. Specify Diagnostic File Usage Click the Diagnostics button on the View →Calculate to display the Diagnostics dialog. On this dialog, select the files you want displayed during the swab, surge, and reciprocation operation calculations. Check Edit Input File to have the Edit Input File dialog appear before the calculation routine starts. This dialog contains an ASCII text file that you can view and edit the data used in the engineering calculations. Editing this data changes the data displayed in the results views (plots, tables, and reports). It will not change the data entered in any dialogs or spreadsheets. Check Show Output File to have the Show Output File dialog appear after the calculation routine is finished. This dialog contains a diagnostics report as an ASCII text file that you can use to view and edit the results from the engineering calculations. Editing this file does not change the results views. When you edit either of these files you do not change the values in any dialogs or spreadsheets. Landmark WELLPLAN 325 Chapter 6: Surge Analysis After the calculations are finished, and if you marked Show Output File, the Diagnostics report appears. When finished, click OK to close the dialog. The calculation routine is complete. Use the View menu Single Operation Plot, Multiple Operation Plot, Table, and Report options to display the calculated results. Check to edit the input data file. Check to display the output file. Analyzing Results Results for the Surge analysis are presented in plots, tables and a report. All results are available using the View menu. The analysis results must be calculated using View →Calculate before generating any plots, tables or the report. If not, data will not be available or the data presented will be inaccurate. Plots The Surge module has several plots that will assist you while analyzing results. The plot data can be displayed as a table. Right-click inside the plot to display its context menu, and then click Switch. Each plot represents results for tripping or reciprocating one stand of pipe. Multiple Operation Plots Trip Speed vs Moving Pipe Depth Use this plot to display the trip speed at a moving pipe depth for various operations. You can plot any of the surge, swab, and reciprocation operations that are defined in the Surge Operations Data→Operations tab. Several operations can be plotted simultaneously. 326 WELLPLAN Landmark Chapter 6: Surge Analysis Trip speeds are specified on the Parameter→Surge Operations→Details button→Analysis Depths tab for tripping operations. For reciprocation operations, the trip speed is determined by the stroke length and strokes per minute specified on the Parameter→Surge Operations→Details button→Analysis Details→Reciprocation Data tab Surge Limit Plot Use this plot to view the maximum pressures at a depth of interest versus various operations compared to the fracture pressure. You can plot any of the surge, swab, and reciprocation operations that are defined in the Surge Operations Data→Operations tab. Several operations can be plotted simultaneously. Due to dynamic sloshing and backflow effects, maximum pressures during a swab may exceed the fracture pressure, and minimum pressures during a surge may drop below the pore pressure. To help you obtain a complete evaluation of the operation, you should review both the surge and swab limit plots. Landmark WELLPLAN 327 Chapter 6: Surge Analysis Plot refers to one depth of interest only. Red portion of the plot (shaded in this picture) indicates fracture gradient pressure. Similar red areas are displayed for pore pressures. This plot indicates the maximum pressure that will occur at one depth of interest at the specified moving pipe depths for the defined operations. To view the plot at 5,700 ft MD, click the right mouse button. Choose Data Selection and select 5,700 ft. Click OK. Data at the selected depth displays on the plot. Highlight the Highlight the depth of interest operations you you want want displayed displayed in the in the plot. plot. 328 WELLPLAN Landmark Chapter 6: Surge Analysis Red (shaded) area indicates fracture gradient. Anticipated pressures during reciprocation will exceed the fracture gradient. From the plot you can see that the fracture gradient has been exceeded during the reciprocation operation as it is currently defined. Reduce the strokes to three strokes per minute (Parameter→Surge Operations→Details button→Analysis Details→Reciprocation Data) and calculate the results again. The following plot indicates that reciprocating with three strokes per minute will not exceed the fracture gradient. The red (shaded) area is no longer displayed on the plot because the pressures will not exceed the fracture gradient. Swab Limit Plot Use this plot to view the minimum pressures at a depth of interest versus various operations compared to the pore pressure. You can plot any of the surge, swab, and reciprocation operations that are defined in the Surge Operations Data→Operations tab. Several operations can be plotted simultaneously. Landmark WELLPLAN 329 Chapter 6: Surge Analysis Due to dynamic sloshing and backflow effects, maximum pressures during a swab may exceed the fracture pressure, and minimum pressures during a surge may drop below the pore pressure. To help you obtain a complete evaluation of the operation, you should review both the surge and swab limit plots. At 5700 ft, the swab pressures will be greatest while tripping in. Transient Response Plot Use this plot to display the transient pressure responses for one or more operations, at one depth of interest and one moving pipe depth versus the time to trip one stand of pipe. You can plot any of the surge, swab, and reciprocation operations that are defined. Why use transient pressure analysis instead of steady-state? Pressures on this plot can be compared to the specified formation pore and fracture pressure limits displayed as red areas on the plot. This plot can easily display a significant advantage of using a transient pressure analysis rather than a steady-state model. The relatively constant pressure displayed on the plot is the “steady-state” pressure. Notice the pressures above and below this steady-state pressure. These pressure changes can be significant, and are calculated using the transient pressure model. What is this plot telling me? The pressure fluctuations at the left side of this plot display the sloshing and damping effects on the pressure behavior. This behavior is caused 330 WELLPLAN Landmark Chapter 6: Surge Analysis by the acceleration and deceleration of the pipe as the pipe motion begins and ends. As an example, during a tripping in (surge) operation, the fluid will begin to compress. As a result, the pressure will increase. Eventually the fluid will begin to flow from the annulus, and the pressure will decrease. This cycle will continue until the pressure fluctuations dampen as a result of the friction in the fluid. As this occurs, the curve flattens to a relative constant, or “steady-state” pressure as displayed on the plot. The relatively constant pressure continues until the pipe motion begins to stop. As the motion stops, the fluid continues to flow from the annulus, and therefore the pressure will decrease. Some pressure fluctuations will occur as the pipe and fluid motion ceases. The reverse of this explanation holds for a tripping out (swab) operation. For reciprocation operations, refer to the portion of the plot displaying the peaks and valleys, or sine wave shape. The overall shape of the curve displays the pressure fluctuations resulting from each stroke. (Note that if you are optimizing trip time, the strokes per minute could be adjusted.) Imposed on the overall curve shape are some “wiggles” or smaller fluctuations in pressure as the curve follows the general sine wave pattern. These “wiggles” are caused by the transient pressure changes as the fluid is opposing the motion of the string. It can be confusing to display the reciprocation and tripping operations on the same plot because the pressure variations with time are difficult to correlate. Landmark WELLPLAN 331 Chapter 6: Surge Analysis Spikes in the reciprocation curve indicate the pressure changes resulting from the strokes. Initial movement of pipe. Curves flatten as the initial fluid movement is taking time to reflect back. This is the “steady- state” pressure. For a reciprocation operation, this plot is modified two ways. l Most of the initial circulation used to reach a steady-state prior to reciprocation is deleted from the plot. Therefore, the time scale should be viewed as incremental time, and not absolute time. l The reciprocation event is cut off from the plot so that only the rise/ fall pressure is drawn. In other words, for slow-stroke speeds, the flat constant pressure portions of the curves are extracted from the plots. Therefore, the accelerations and decelerations along with maximums and minimums are presented for consecutive strokes, and the full transient response is cut off to allow the key information to be presented as a single plot. Hook Load vs. Trip Time Plot Use this plot to display the hook load for a moving pipe versus trip time for various operations. You can plot any of the surge, swab, and reciprocation operations that are defined in the Surge Operations Data→Operations tab. Several operations can be plotted simultaneously. 332 WELLPLAN Landmark Chapter 6: Surge Analysis Tripping out has a Peaks correspond to positive change in strokes. hook load. The rate of change in hook load decreases as you near the end of a stand. Tripping in has a negative change in hook load. Surge Limit Plot @ Moving Pipe Depth Use the Surge Limit Plot @ Moving Pipe Depth plot to view the maximum pressures at a moving pipe depth versus various operations compared to the fracture pressure. Moving pipe depth is defined in the Surge Operations Data→Analysis Parameters tab. You can plot any of the surge, swab, and reciprocation operations that are defined in the Surge Operations Data→Operations tab. Several operations can be plotted simultaneously. Due to dynamic sloshing and backflow effects, maximum pressures during a swab may exceed the fracture pressure, and minimum pressures during a surge may drop below the pore pressure. To help you obtain a complete evaluation of the operation, you should review both the surge and swab limit plots. Landmark WELLPLAN 333 Chapter 6: Surge Analysis None of the operations exceed the pore pressure or fracture gradient limits. Swab Limit Plot @ Moving Pipe Depth Use the Swab Limit Plot @ Moving Pipe Depth plot to view the minimum pressures at a moving pipe depth versus various operations compared to the pore pressure. Moving pipe depth is defined in the Surge Operations Data→Analysis Parameters tab. You can plot any of the surge, swab, and reciprocation operations that are defined in the Surge Operations Data→Operations tab. Several operations can be plotted simultaneously. Due to dynamic sloshing and backflow effects, maximum pressures during a swab may exceed the fracture pressure, and minimum pressures during a surge may drop below the pore pressure. To help you obtain a complete evaluation of the operation, you should review both the surge and swab limit plots. None of the operations exceed the pore pressure or fracture gradient limits. 334 WELLPLAN Landmark Chapter 6: Surge Analysis Miscellaneous Plots Surface Results The Surface Results plot displays the standpipe pressure, block speed, and bit velocity versus times for a single operation at one moving pipe depth. Plot pertains to one moving pipe depth. Transient Results The Transient Results plot has the moving pipe depth at various times while tripping one stand of pipe. Use the plot to determine how fast the bit is moving when it is located at various depths. Landmark WELLPLAN 335 Chapter 6: Surge Analysis Report Report Options The Report Options dialog is used to specify what additional information will be included on the report. Using this dialog, you can include or exclude much of the information defining the case you are analyzing. Surge Report This report describes drill string and wellbore input data, mud properties, and booster pump properties. 336 WELLPLAN Landmark Chapter 6: Surge Analysis Supporting Information and Calculations The material contained in this section is intended to provide you more detailed information and calculations pertaining to many of the steps presented during the descriptions of the analysis mode methodologies. If the information in this section does not provide you the detail you require, please refer to “References” on page 346 for additional sources of information pertaining to the your topic of interest. Methodology The surge calculations are divided into two regions: the interval from the surface to the end of the pipe and the interval from the end of the pipe to bottomhole. In the upper region, pipe pressures are coupled to annulus pressures through the radial elasticity of the pipe. The interpolated method of characteristics is used to solve the fluid flow and pipe dynamics for these “Coupled Pipe-Annulus” and “Pipe-To- Bottomhole” regions. The fluid flow and pipe velocity equations are solved subject to the boundary conditions given below. The maximum time step allowed is the minimum grid spacing divided by the sonic velocity. For a drill string near bottomhole, the minimum gird spacing will be the distance off bottom. In order to avoid very small time-step sizes for surges near bottomhole, a “near bottomhole” element has been defined for this special case that neglects inertia. Many of the mass equations have terms that relate the flow cross- sectional area to the fluid pressures. For instance, in the “Coupled Pipe- Annulus” region, increasing tubing pressure increases the tubing cross- sectional area and decreases the annulus cross-sectional area. Expansion of the pipe cross-sectional area is governed by “thick-wall” pipe elastic solutions. Pressure and Temperature Behavior of Water Based Muds Temperature and pressure behavior of water-based muds is very complex and dependent on mud composition and chemistry. There are two water-based mud models in Surge. The simplest water-based mud model used by Surge is the results from Annis combined with a comprehensive water viscosity correlation. Landmark WELLPLAN 337 Chapter 6: Surge Analysis The more generalized water-based mud model uses Alderman, Gavignet, Guillot, and Maitland to provide a pressure-temperature correlation for user-supplied viscometer data as well as an improved model for low shear-rate flow. The fluid model is based on the Casson equation for non-Newtonian fluids. Viscosity Correlations of Oil Based Muds Temperature and pressure behavior of oil-based muds is equally complex and dependent on mud composition and chemistry. As for water-based muds, there are two oil-based mud models in Surge. For the simplest model, viscosity correlations for oil-based muds are based on the work of Combs and Whitmire. The more generalized oil-based mud model uses Houwen and Geehan for improved pressure-temperature correlation to viscometer data, as well as an improved model for low shear-rate flow. The fluid model is based on the Casson equation for non-Newtonian fluids. Surge Analysis Two Analysis Regions The dynamic surge analysis considers two distinct regions: l Coupled-pipe/annulus region l Pipe-to-bottomhole region 338 WELLPLAN Landmark Chapter 6: Surge Analysis These two regions are visible in the following picture. The Coupled-Pipe/Annulus Region Features: l The full balance of mass and balance of momentum for pipe and annulus flow are solved. l Pipe and annulus pressures are coupled through the pipe elasticity. Annulus pressures caused by pipe pressures may be significant. l Longitudinal pipe elasticity and fluid viscous forces determine pipe displacement. Referring to the following picture, we can see that the velocity of the pipe end is not necessarily equal to the velocity Landmark WELLPLAN 339 Chapter 6: Surge Analysis imposed at the surface. Therefore, the block speed does not necessarily equal the speed of the bit. l Frictional pressure drop is solved for laminar flow in an annulus with a moving pipe for power-law fluids. Turbulent-flow frictional pressure drop uses the Dodge and Metzner friction factor for power-law fluids. l Fluid properties vary as a function of pressure and temperature. Plastic viscosity and yield point can vary significantly with temperature. l Formation elasticity, pipe elasticity and cement elasticity are all considered in determining the composite elastic response of the wellbore. For the case of a pipe cemented to the formation, use of only the pipe elasticity will not give conservative surge pressures. The Pipe-To-Bottomhole Region Features: l Balance of mass and balance of momentum for the pipe-to- bottomhole flow are solved. l Frictional pressure drop is solved for laminar flow in the pipe-to- bottomhole region for power-law fluids. Turbulent flow frictional pressure drop uses the Dodge and Metzner friction factor for power-law fluids. l Fluid properties vary as a function of pressure and temperature. 340 WELLPLAN Landmark Chapter 6: Surge Analysis l Formation elasticity, pipe elasticity and cement elasticity are all considered in determining the composite elastic response of the wellbore. Connecting the Coupled-Pipe/Annulus and the Pipe-to-Bottomhole Regions The two regions are connected through a comprehensive set of force and displacement compatibility relations. l The elastic force in the moving pipe is equal to the pressure below the pipe times the pipe-end area. This means that a sufficiently high pressure below the pipe could retard the pipe motion. l Mass-flow balances are calculated for flow through the pipe nozzle, the annulus return area and into the pipe bottomhole region. The surge force and displacement and compatibility relations are illustrated in the following diagram. l Pressure drops are calculated through the pipe nozzle and annulus return area on the basis of cross-sectional area changes with appropriate discharge coefficients. l Boundary conditions for floats were chosen to allow one-way flow through the float. Fluid is allowed to flow out of the float, otherwise the float is treated as a closed pipe. Landmark WELLPLAN 341 Chapter 6: Surge Analysis l Surface boundary conditions set the fluid pressures in the tube and the annulus to atmospheric pressure. The bottomhole boundary condition assumes a rigid floor, which requires a zero fluid velocity. Open Annulus Calculations Mass Balance The Mass Balance consists of three parts: l Expansion of the hole caused by internal fluid pressure (dA/dP). l Compression of the fluid resulting from the changes in fluid pressure. l Influx (or outflux) of the fluid. Hole expansion is a impacted by the elastic response of the formation and any casing cemented between the fluid and the formation. The fluid volume change is given by the bulk modulus, K. For drilling muds, K is a function of the composition, pressure, and temperature of the mud. K is the reciprocal of the compressibility. 1 dA 1 dP 1 ∂ + + q=0 A dP K dt A ∂z Momentum Balance This equation consists of four parts. The left side of the equation represents acceleration of the fluid. The acceleration of the fluid equals the sum of the forces on the fluid. The forces on the fluid are represented by the three terms on the right side of the equation. The first fluid force term represents the pressure or viscous force. The middle term on the right side is the drag and is a function of the fluid velocity. The final term is the gravitational force. ρ d ∂P q=− + h(q ) + ρg cos Θ A dt ∂z 342 WELLPLAN Landmark Chapter 6: Surge Analysis Where: A = Cross-sectional area P = Pressure K = Fluid bulk modulus q = Fluid volume flow rate ρ = Fluid density h = Frictional pressure drop g = Gravitational constant Θ = Angle of inclination of annulus from vertical Coupled Pipe Annulus Calculations Four partial differential equations define this region. These balance equations are similar to the equations for the Open Annulus. However, there are two important differences. l In the balance of mass equations, an extra term is added to account for the pressures both inside and outside of the pipe. For example, increased annulus pressure can decrease the cross-sectional area inside the pipe and increased pipe pressure can increase the cross- sectional area because of pipe elastic deformation. l The second major difference is the effect of pipe speed on the frictional pressure drop in the annulus as given by the frictional pressure drop term. Pipe Flow Mass Balance 1 dA1 1 dP1 1 dA1 dP2 1 ∂ + + + q1 = 0 A1 dP1 K 1 dt A1 dP2 dt A1 ∂z Momentum Balance ρ1 d ∂P q1 = − 1 + h(q1 − A1v3 ) + ρ1 g cos Θ A1 dt ∂z Landmark WELLPLAN 343 Chapter 6: Surge Analysis Annulus Flow Mass Balance ρ1 dA2 dP1 1 dA2 1 dP2 1 ∂ + + + q2 = 0 A2 dP1 dt A2 dP2 K 2 dt A2 ∂z Momentum Balance ρ2 d ∂P q 2 = − 2 + h2 (q 2 , v3 ) + ρ 2 g cos Θ A2 dt ∂z Pipe Motion The following equation is the balance of momentum for the pipe. The pipe inertia is represented by the left side of the equation. The first term of the right side is the longitudinal elasticity of the pipe (using Young’s modulus, E). The second and third items provide the hoop-stress effect (increased inside pressure shortens the pipe and increased outside pressure lengthens the pipe). The final three terms define the effect of viscous drag on the pipe. Variations in fluid velocity, relative to the pipe velocity, inside the pipe and in the annulus affect the shear stress at the pipe. Momentum Balance d2 ∂ 2 v3 ∂ dP1 ∂ dP2 d d d ρ3 v3 = E + f1 + f2 + f 3 q1 + f 4 q 2 + f 5 v3 dt 2 ∂z 2 ∂ z dt ∂z dt dt dt dt 344 WELLPLAN Landmark Chapter 6: Surge Analysis Where: A1 = Pipe flow area K1 = Pipe fluid bulk modulus P1 = Pipe fluid pressure q1 = Pipe fluid volume flow rate h = Pipe frictional pressure drop ρ1 = Pipe fluid density A2 = Annulus flow area K2 = Annulus fluid bulk modulus P2 = Annulus fluid pressure q2 = Annulus fluid volume flow rate h2 = Annulus frictional pressure drop ρ2 = Annulus fluid density E = Pipe elastic modulus v3 = Pipe velocity ρ3 = Pipe density f1 , f 2 = Hoop strain coefficients f3 , f4 , f5 = Fluid shear stress coefficients g = Gravitational constant Θ = Angle of inclination from vertical Landmark WELLPLAN 345 Chapter 6: Surge Analysis References Transient Pressure Surge Mitchell, R. F. “Dynamic Surge/Swab Pressure Predictions.”, SPE Drilling Engineering, September 1988, (pages 325-333). Lal, Manohar. “Surge and Swab Modeling for Dynamic Pressures and Safe Trip Velocities.” Proceedings, 1983 IADC/SPE Drilling Conference, New Orleans (427-433). Lubinski, A., Hsu, F. H., and Nolte, K. G. “Transient Pressure Surges Due to Pipe Movement in an Oil Well.” Fevue de l’Inst. Franc. Du Pet., May — June 1977 (307-347). Wylie, E. Benjamin, and Streeter, Victor L. Fluid Transients, Corrected Edition (1983). FEB Press, Ann Arbor, Mich., (1982). Validation Rudolf, R.L., Suryanarayana, P.V.R., Mobil E&P Technical Center, “Field Validation of Swab Effects While Tripping-In the Hole on Deep, High Temperature Wells “, SPE 39395. Samuel, G.R., Sunthankar, A., McColpin, G., Landmark Graphics, Bern, P., BPAmoco, Flynn,T., Sperry Sun, “Field Validation of Transient Swab/Surge Response with PWD Data”, SPE 67717. Pipe and Borehole Expansion Timoshenko, S. P., and Goodier, J. N., “Theory of Elasticity”, McGraw- Hill Book Company, New York, 1951. Frictional Pressure Drop Savins, F. J. “Generalized Newton (Pseudo-plastic) Flow in Stationary Pipes and Annuli.” Pet. Trans. AIME (1958). Dodge, D.W., and Metzner, A. B. “Turbulent Flow of Non-Newtonian Systems,” AIChEJ (June 1959). 346 WELLPLAN Landmark Chapter 6: Surge Analysis Fontenot, J. E., and Clark, R. E.: “An Improved Method for Calculating Swab and Surge Pressures and Calculating Pressures in a Drilling Well, “Society of Petroleum Engineering, October 1974 (451-462). Schuh, F. J. “Computer Makes Surge-Pressure Calculations Useful.” Oil and Gas Journal, August 1964 (96). Pressure and Temperature Fluid Property Dependence Annis, Max R. “High Temperature Flow Properties of Water-Base Drilling Fluids.” J. Pet. Tech., August 1967. Alderman, N. J., Gavignet, A., Guillot, D., and Maitland, G. C.: “High Temperature, High Pressure Rheology of Water-Based Muds,” SPE 18035, 63rd Annual Technical Conference and Exhibition of the SPE., Houston, (1988 (187-196). Combs, G. D., and Whitmire, L. D. “Capillary Viscometer Simulates Bottom Hole Conditions.” Oil and Gas Journal, September 30, 1968 (108-113). Houwen, O. H. and Geehan, T.:”Rheology of Oil-Based Muds.” SPE15416, 61st Annual Technical Conference and Exhibition of the SPE, New Orleans (1986). Uner, D., Ozgen, C., and Tosun, I. “Flow of a Power-Law Fluid in an Eccentric Annulus” SPEDE, September 1989 (269-272). Johancsik, C. A., Friesen, D. B., and Dawson, R. “Torque and Drag in Directional Wells — Prediction and Measurement.” J. Pet. Tech., June 1984 (987-992). Landmark WELLPLAN 347 Chapter 6: Surge Analysis 348 WELLPLAN Landmark Chapter 7 Cementing-OptiCem Analysis Cementing can be used to optimize cementing operations and minimize the possibility of costly cementing errors. Overview In this section of the course you will become familiar with all aspects of using Cementing to design your cementing operations. You will become familiar with entering analysis data and using plot, reports, and tables to analyze the results. To reinforce what you learn in the course lecture, you will complete several exercises designed to prepare you for using the program outside of class. The information presented in this chapter can be used as a study guide during the course, and can also be used as a reference for future cement job planning. Landmark WELLPLAN 349 Chapter 7: Cementing-OptiCem Analysis Cementing Analysis: An Introduction What is Cementing? The Cementing module can be used to predict what occurs in the well during cementing operations. Cementing can be used to evaluate the effects of various conditions on the simulated cementing operation. You can use Cementing to calculate: • Safe pump rates • Surface pressure • Downhole pressures • Nitrogen concentration • Foam volume • Downhole rheology • Temperature thinning of fluids 350 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis Workflow q Activate Cementing by clicking the button. q Open the Case. (File →Open Case) If you have created a new case, save the case. (File →Save As) q Enter general information about the case. (Case →General) q If this is an offshore well, enter water depth and well type. (Case →Offshore If this isn’t an offshore well, you won’t be able to access this dialog.) q Define the wellbore. (Case →Wellbore) q Define the workstring. Use the same dialog to define all workstrings (drillstrings, casings, liners, etc.) (Case →String) q Enter deviation (survey) data. (Case →Deviation→Survey Editor) q Define the fluids used. You will probably need to enter mud and cement. You must define the fluid rheological properties, select a rheology model, and specify the temperature. You can define as many fluids as you want. (Case→Fluid Editor) q Define the pore pressure gradients. (Case →Pore Pressure) q Define the fracture gradients. (Case →Frac Gradient) q Specify centralizer information. (Parameter→Centralizer Placement) q Specify cement job data including volumes, fluids used, back pressure and whether or not this is a foam job. (Parameter→Job Data) q If this is a foam job, specify the foam job data. (Parameter→Foam Data) q Specify wellbore temperatures, depths of interest and whether or not returns are taken at the sea floor. (Parameter→Additional Data) Landmark WELLPLAN 351 Chapter 7: Cementing-OptiCem Analysis q Specify additional pressure that may be required to seat the plug and the eccentricity (standoff) to be used in the calculations. (Parameter→Data Analysis) q Analyze the results. 352 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis Using Cementing Analysis Mode Starting Cementing Analysis There are two ways to start the Cementing Module. l Select Cementing from the Modules menu. l Click the Cementing button. Entering Case Data The example case used in this portion of the course is titled “Cement 7 inch casing” in the project “Guided Tour” and well “Tour #1.” Please open this case now. The Cementing module uses the information input on the Case menu. Entry of much of this information is discussed in the section “Entering Case Data” on page 40 of Basics chapter of this manual. The next few pages will discuss entry of information that is not discussed in the Basics chapter of this manual. If you have a question that is not addressed in this chapter, you may want to refer to the Basics chapter for additional information on using the General, Offshore, Wellbore Editor, String Editor, Deviation, Pore Pressure, and Frac Pressure dialogs. Although the Fluid Editor is common to all modules, it will be discussed here in this section again because entry of cement data has not been covered before. Define Fluids Used During the Cement Job Use the Case→Fluid Editor tabs to specify the rheological model and other basic characteristics about simple drilling muds, spacers, or cement slurries Two tabs are used to specify fluids used during a cement job. These include: l Standard Muds Tab: Use this tab to define drilling muds and spacers. l Cement Slurries Tab: Use this tab to define cement slurries. Landmark WELLPLAN 353 Chapter 7: Cementing-OptiCem Analysis You can also import fluids from fluid libraries and export fluids defined in this dialog to the fluid libraries. Defining Muds and Spacers Use the Case→Fluid Editor→Standard Fluids tab to define drilling fluids and spacers by specifying the basic characteristics of the fluid using the fields provided. You can also import fluids from fluid libraries and export fluids defined in this tab to the fluid libraries. This tab was discussed in the Basics chapter of this manual. The data for the spacer has been entered for you. Be sure to select the correct Type from the drop-down list. You can choose from Spacer and Non Spacer. Defining Cement Slurries Use the Case→Fluid Editor→Cement Slurries tab to define the cement slurries you will be using. You can define multiple cements using the tab. You can also import or export cements to libraries using this tab. 354 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis The following defines the lead cement. Enter this data as described below. Use the Import To Library or Export From Library buttons to import a cement from the Click New to enter a new cement. library or to export a cement to the library. Highlight an existing cement name if you want to edit data defining an existing cement.The data displayed pertains to the highlighted cement. Highlight the temperature for which you will specify rheology data. In this example, there is only one temperature specified, but you can have more than one temperature. All data specified in the Rheology Tests pertains to the highlighted temperature. Landmark WELLPLAN 355 Chapter 7: Cementing-OptiCem Analysis In this example, we want to use a tail slurry also. Review the data entered in the following dialog. Tail Slurry is highlighted. Therefore, all data on this tab pertains to the cement named Tail Slurry. Notice that this cement has rheological data defined for two temperatures. Define Job Information In the Basics chapter you became familiar with the Options and Comments tabs on the Case →General dialog. For Cementing analysis, the General dialog has an additional tab called the Job Information tab. Entry of information on this tab is optional. In this example, we will not use this tab. Specify the Volume Excess % If you remember from the Basics section of this course, the Wellbore Editor is used to define the wellbore as the current workstring sees it. You can also use the Case→Wellbore dialog to specify the extra percentage of annular cement volume required for an enlarged wellbore. This volume will be based on the Effective Hole Diameter field. For open hole sections, the Effective Hole Diameter is used to represent the 356 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis actual size of the hole. If you specify the Effective Hole Diameter, the Volume Excess % is calculated based on Effective Hole Diameter. Similarly, if you specify the Volume Excess %, the Effective Hole Diameter will be calculated. For example, if you are drilling an 8.5 inch hole that is 10% overgauge, enter 8.5 for Hole Diameter and 10 for Volume Excess %. The extra volume will be calculated. Do not use the Volume Excess % field to raise the cement top. Use Parameter →Job Data to raise the cement top. Be careful that you don’t enlarge the wellbore in the Hole Diameter field and then again using the Volume Excess % field. Enter the Volume Excess % and the Effective Hole Diameter is calculated. Specify the Standoff or Calculate the Centralizer Placement Use the Parameter →Centralizer Placement dialog to calculate the spacing between multiple centralizers and/or the variable standoff between the casing and wellbore. Alternately, you can enter a manual standoff value that applies to the entire well. Before using this dialog, you should use the Centralizer Editor to specify all centralizers if you plan on using centralizers not already in the catalog. A special button lets you access the Centralizer Editor to define additional centralizers. Landmark WELLPLAN 357 Chapter 7: Cementing-OptiCem Analysis Centralizer placement calculations are typically performed before wellbore simulation. These calculations can also be performed independently using the Centralizer Placement mode. Dialog Field Descriptions Calculate Standoff/Spacing Select this option if you want to use this window to calculate spacing and/or standoff values. The remaining entries in this window will help you build the spreadsheet. Standoff is the ratio of the largest to smallest distances between the casing and wellbore. Standoff is 100% when the casing is perfectly centered in the wellbore and declines as the casing becomes off-centered. If casing is against the wellbore, standoff would be 0%. Entered Standoff Select this option if you want to enter a standoff manually. A good value for standoff is 80%. A value of 70% is adequate. If you select this option, all other fields except Top of Centralized Interval will become inactive because the centralizer placement will not be calculated. Fluid Profile These entries specify whether the standoff/spacing calculations will use the density of the fluids at the end of the cement job, or only a single mud density. If you select As Top Plug Lands, the fluid profile will be taken from the Parameter →Job Data dialog. If you select During Mud Conditioning, then enter the Mud Density value immediately before the casing is run. If the wellbore fluid density has been entered elsewhere, it will be automatically specified here. 358 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis Spacing Limits (Between Centralizers) Enter the Maximum Distance and Minimum Distance values that the program can use when calculating the spacing between centralizers. Top of Centralized Interval If desired, you can specify a Measured Depth and Standoff above the top of the centralized interval. To do this, turn on the check box next to the Top of Centralized Interval field and enter the values. Enter the depth measured from the Kelly bushing to the top of the interval to be centralized. Specify the percentage value for standoff above the top. The default value of 40 percent is typical. This represents the resulting standoff in the upper portion of the well caused by the suspended weight below and the centering effect of the slips. Centralizer Editor button Click the Centralizer Editor button if you want to define more centralizers. Typically, you will do this if you do not see the desired centralizers in the drop-down lists under the second and third column of the spreadsheet. Centralizer Spreadsheet Use the spreadsheet area on the right side of the dialog to specify centralizer patterns and calculate standoff and spacing for each. The first three columns contain drop-down lists that you can use to select a centralizer pattern and to specify the centralizers in each interval. The remaining columns let you enter specific depths and standoffs, and either enter or calculate the spacing. Pattern Column The pattern column allows you to optionally switch back and forth between multiple centralizers within a single constant interval. From the drop-down list, Pattern A is normal and uses a single centralizer for the interval. All other patterns alternate between the two specified centralizers in the manner suggested by the lettering. Centralizer A, Centralizer B Columns Use these two fields to select the centralizers to be used for this interval. The drop-down list shows centralizers defined in the Centralizer Editor. Use the Centralizer B column only if you are using a pattern other than A (AB, AAB, AABB, or AAAB). The list of centralizers available comes from the centralizer database. Define the Cement Job The Job Data dialog lets you define crucial job information such as tracer fluid types, rate, volume, and placement for each fluid in the cementing job. Landmark WELLPLAN 359 Chapter 7: Cementing-OptiCem Analysis Job Data Dialog Field Descriptions Automatic Rate Adjustment Select this check box to allow the program to automatically adjust the pumping rate so that the pressure at the fracture zone depth remains less that the fracture gradient minus the safety factor. The pumping rate is automatically adjusted down to a minimum of 0.5 bpm [0.08 m³], if required. To use a rate less than 0.5 bpm, turn this option off and enter the rate manually. Safety Factor When the Automatic Rate Adjustment option is selected, the safety factor specifies how close the ECD can come to the entered fracture gradient before the program reduces the rate to a safe value. Mud Erodibility Mud Erodibility as used in cementing and OptiCem refers to the ability of the wellbore fluid to be eroded away by a different fluid passing by it in the annulus of the well. First, you need to enter the rheological parameters of the fluids you will be pumping into the well (cement, spacers/flushes, etc.). OptiCem uses these values to calculate the erosion that occurs as these fluids pass by the wellbore fluid. It then uses this erodibility that has occurred to calculate a displacement efficiency. For example, if the erodibility graph shows 80% displacement efficiency, basically 80% of the wellbore fluid was removed. This calculation applies to 5% of the temperature differential of the chosen zone of interest. The Mud Erodibility option is available only to Halliburton users. If you need this calculation performed, please contact your local Halliburton Zonal Isolation Group. 360 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis Tracer Fluid A tracer fluid allows you to track a certain fluid in the wellbore during the course of the job. Typically, this is assigned to the cement slurry (lead cement slurry, if two are being pumped). The tracer fluid is displayed in the ‘Volume and Rate Calculations’ and ‘Free Fall Calculations’ tables in the simulated output of the report document. From the drop-down list, select the fluid you want to use as the tracer fluid. The tracer fluid drop-down list is blank until the stage table types are selected. The initial wellbore fluid cannot be a tracer fluid. Usually the lead cement stage is selected as the tracer fluid from the drop-down list. The leading edge of the tracer fluid is a reference point for tracking fluid movement. The value is negative as the fluid is moving down the well in the casing string, and positive as it begins to move up the well in the annulus. The position of the selected tracer fluid is shown in the report document. OptiCem actually calculates the movement of all the fluids, but due to size limitations only one can be shown in the report. Use Foam Schedule Check this box to indicate the cement job is using foam. When you are using a foamed cement, you must specify the foam job information using Parameter →Foam Data. If this box is checked, Foam Data option becomes available under the Parameter menu. Otherwise, the Foam Data menu option will not be available. Disable Auto-Displacement Calculation Check this box if you want to disable the automatic calculation of displacement. If this box is not checked, the calculation is performed automatically. Fluid Editor Button Access Case→Fluid Editor in order to define more standard fluids or cement slurries. Typically, you would do this if you do not see the appropriate fluids listed in the drop-down list under the Fluid column of the spreadsheet. Spreadsheet Columns: Type This is the stage name displayed in the report and graphs. This name defaults to the fluid name and can be used to differentiate stages with the same selected fluid. The following types are available: Wellbore The initial fluid at the start of the job, usually the drilling fluid or mud used to circulate. No volume is entered. Landmark WELLPLAN 361 Chapter 7: Cementing-OptiCem Analysis Cement A cement fluid type placed in the annulus. Cement can be subdivided into a lead and tail cement, or as many other parts as required. Displacement Drilling fluid or mud that follows the plug. Shutdown Period of time that pumping has stopped, often while dropping the plug. Spacer/Flush A spacer or flush fluid placed in the annulus or pumped out. Shoe Slurry Specify the cement that is left in the shoe joint after the top plug lands or at the end of the cement job. Spacer on Plug A spacer or flush that follows the plug and remains in the casing. Tuned Spacer A tuned spacer is a special type of spacer that is used in conjunction with the erodibility technology. Once you can identify the Required Shear Stress of the fluid to be removed, you can “tune” a spacer system rheologically to remove it. Mud A drilling fluid or mud that can be placed in the annulus, much like a spacer. Mud can be in the wellbore before the cement job or it can be used to displace the slurry. Fluid This is the selected fluid as defined in the Fluid Editor. Rate The rate the selected fluid will be pumped into the well, in barrels per minute. Stroke Rate The stroke rate in strokes per minute. You must enter a volume per stroke on the Circulating System dialog to use strokes. Shutdown Time If Shutdown is selected in Type, a time must be entered in this field; all other fields become inactive. Placement Method The Placement Method column defines how volumes are calculated for each stage. When the calculations are performed, the omitted information in the table is filled in automatically. The drop-down list contains Top of Fluid, Length, Volume, and Bulk & Yield. Volume Enter the volume for this stage, and Top of Fluid and Length are calculated. If you wish to calculate stage volumes, enter information for the stages you are pumping in the order they are to be pumped. Each stage must have one of the following columns 362 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis entered, depending on the Volume calculation option: Top of Fluid, Length, Bulk Cement. Strokes The number of strokes. You must enter a volume per stroke on the Circulating System dialog to use strokes. Top of Fluid Enter the measured depth for the top of the fluid in the annulus at the end of the job. The volume and length are calculated. Length Enter the measured length of this stage in the annulus at the end of the job. The volume and top of fluid are calculated. Bulk Cement Enter the number of sacks to be mixed for this cement stage. The volume, length, and top of fluid are calculated. Back Pressure Schedule Back Pressure is the absolute (not gauge) pressure held on the top of the annulus during pumping. You can simulate a job with any back pressure or combinations of back pressures. If the annulus is to be left open to the atmosphere during the entire job, then 14.7 psi [101 kPa] should be entered for the back pressure value and 0 should be used for the return volume. If several back pressure values are to be used, then enter zero for the return volume of the last back pressure. This indicates that the pressure will be maintained throughout the remainder of the job. Back pressure is often used for one of three reasons: • To compress foam near the surface. When foam is circulated back to the surface, densities can become too light. The application of back pressure before circulating the foam to surface can increase the density of the near surface foam. • To control annular gas migration. Back pressure has also been used as an anti-gas migration technique. Back pressure has been shown to be effective only if applied immediately after the plug lands, prior to the development of gel strength of the slurry in the annulus. • To prevent or minimize free fall. If free fall must be controlled or eliminated, back pressure can be incrementally increased during free fall. Return Volume If the entire job is to be run at one back pressure, then the Return Volume value should be zero. If several back pressure values are Landmark WELLPLAN 363 Chapter 7: Cementing-OptiCem Analysis used, the Return Volume value for the last pressure should be zero, because the last pressure remains in effect until the plug is down. Define Temperatures, Depths of Interest and Offshore Returns Information The Additional Data dialog is used to enter data for the Wellbore Simulator mode in the Cementing module (OptiCem). This dialog allows you to enter and manage offshore, zone depth, and temperature information. Do not check this box because we are not taking returns at the sea floor. Reservoir Zone and Fracture Zone are the same in this case. Offshore Information Returns at Sea Floor Check this box to indicate there are returns at the sea floor. Use this option when you have a subsea wellhead and no riser. If you are taking returns at the sea floor, you must specify the sea water density. Sea Water Density Enter a value in this field when you have clicked the check box for Returns at Sea Floor. Depths of Interest for Plots (MD) Reservoir Zone Enter a value for the depth where the pore pressure gradient is a maximum. 364 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis Fracture Zone Enter a value for the depth where you are concerned about fracturing the formation. Temperature Information BHCT button The temperature profile can be calculated in one of several ways. If the Bottom Hole Circulating Temperature (BHCT) is known, then click this button and enter the BHCT, Surface Temperature, and Mud Outlet Temperature in the fields that become active below. Calculate API BHCT button To calculate the API BHCT (bottom hole circulating temperature), click this button and enter the Mud Outlet Temperature and Bottom Hold Static Temperature as described below. Temperature Profile button The temperature profile can be calculated in one of several ways. If the Bottom Hole Circulating Temperature (BHCT) is known, then you can enter this temperature along with Surface Temperature and Mud Outlet Temperature. To calculate the API BHCT, enter the Bottom Hole Static Temperature (BHST) and Mud temperature. NOTE: The WellCat thermal simulator can create an OptiCem compatible temperature profile data set. This data set contains the casing and annular temperatures at several different depths along the wellbore. If a temperature profile data set is selected, OptiCem uses that temperature profile in its simulation. Some sample temperature profiles are available with this application and use the filename extension *.HCT. You may access temperature profiles or enter temperature profile data by selecting the Edit Profile button and then selecting Import. Edit Profile Button Define the temperature profile to be used or import a temperature profile. BHCT If you have selected the BHCT or Calculate API BHCT options above, then enter the Bottom Hole Circulating Temperature value in this field when it becomes active. Surface Temperature If BHCT is selected above, then enter the Surface Temperature value in this field when it becomes active. Mud Outlet Temperature If BHCT is selected above, then enter the Mud Outlet Temperature value in this field when it becomes active. BHST If Calculate API BHCT is selected above, then enter the Bottom Hole Static Temperature in this field when it becomes active. Landmark WELLPLAN 365 Chapter 7: Cementing-OptiCem Analysis Specify Additional Analysis Parameters The Parameter →Analysis Data dialog provides supplemental control of several values before performing the Wellbore Simulator calculations. Select Eccentricity if eccentricity is to be considered in To ensure proper plug the calculation. If Eccentricity is turned off, then the seating, additional pressure wellbore simulator performs its calculations assuming may be applied to the 100% standoff. If you want the eccentricity calculations casing immediately after at a particular standoff, select the Entered Standoff the plug is landed. option on the Centralizer Placement Dialog. Otherwise, it will run with an actual standoff profile. Erodibility is only available to Halliburton personnel. If you need this option, contact your local Zonal Isolation Group. Check Calculate Automatically for automatic calculation of step size. Enter a Volume Increment (barrels) if simulator step size is not to be calculated automatically. The check box for automatic calculation cannot be selected. NOTE: The Volume Increment is the amount of fluid volume the simulator pumps per iteration. The Calculate Automatically option uses 1.4% of the total job volume rounded to the nearest 5 bbls or 1 m³. Increase this value if the rates or ECD curves have extra spikes. Decrease the value if data is missing between points. Usually you will want to leave the Calculate Automatically option turned on. Analyzing Results Results for the Cementing analysis are presented in plots, tables and a report. All results are available using the View menu. 366 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis What is the Circulating Pressure Throughout the Cement Job? Use the View→Plot→Circ Pres and Den - Frac Zone plot to determine the circulating pressure fluid volume pumped at the fracture zone specified on Parameter→Additional Data. These lines indicate when the The circulating pressure during various stages occur. the displacement stage exceeds the fracture pressure. Fracture pressure The formation breakdown pressure at this depth is indicated by one of the curves on this plot. If the Automatic Rate Adjustment option was selected (on Parameter→Job Data), then a second curve indicates the safety factor. If the circulating pressure exceeds the fracture zone pressure, the fluid can fracture the formation and result in lost circulation from the wellbore. If the circulating pressure exceeds the fracture zone pressure, reduce the pump rates or turn on the Automatic Rate Adjustment option. If reducing the pump rates does not completely solve the problem, decrease the density of one or more fluids (with foamed fluids, or by increasing the nitrogen concentration), or decrease the volume of the heaviest stages. Landmark WELLPLAN 367 Chapter 7: Cementing-OptiCem Analysis If you prefer, you can view this information as ECD versus volume pumped. Click the right mouse button anywhere on the plot to open the plot selection box. Highlight the plot you want displayed and click the left mouse button. This plot displays the pressure as ECD. Is There Free Fall? The View→Plot→Comparison of Rates In and Out plot displays the total annular return rate and corresponding pump rate versus the fluid pumped into the well. This data may be correlated with information in 368 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis the Volume and Rates Calculations table in the Cementing Report. (View→Report) Differences between the two rate curves indicates free fall without nitrogen injection. If free fall occurs and the well goes on vacuum, the rate out will initially exceed, and then fall below, the planned pumped rate. An example of free fall Notice the rate out initially exceeds the rate in. After initial high, rate out then falls below rate in. What is the Surface Pressure? Use the View→Plot→Calculated Wellhead/Surface Pressure plot to view the pressure changes as varying density fluids are pumped at varying rates through the well. If the Surface Iron option was selected (on the Case→Cement Circulating System dialog) this graph is titled Calculated Surface Pressure. This data may be correlated with information in the Volume and Rates Calculations table on the cementing report. The calculated wellhead pressure is lower than pump pressure because of the hydrostatic head and friction in the lines between the pump and cementing head. A horizontal graph line along the x-axis indicates free fall. Often, as the majority of the cement moves from the casing to the annulus, the slope Landmark WELLPLAN 369 Chapter 7: Cementing-OptiCem Analysis of this curve beings to increase. Usually, it continues to increase as the heavier cementing fluids are forced up the annular gap. Free Fall Automatically Adjusting the Flowrate Because the circulating pressure exceeds the fracture pressure using the rates specified on the Parameter→Job Data dialog, you can allow the software to automatically adjust the pump rates. Click the Automatic Rate Adjustment box on the Parameter→Job Data dialog. Click Automatic Rate Adjustment to have the rate adjusted to avoid exceeding the fracture pressure. If you allow automatic rate adjustment, you must specify a Safety Factor. These rates will be adjusted. 370 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis Refer to the View→Plot→Circ Pres and Den - Frac Zone plot to determine the circulating pressure using the adjusted flow rates. In this example, although the circulating pressure no longer exceeds the fracture pressure, it is exceeding the safe pressure (based on the safety factor). The maximum circulating pressure is 83 psi less than the fracture pressure. What Are the Adjusted Rates? The View→Plot→Comparison of Rates In and Out plot displays the total annular return rate and corresponding pump rate versus the fluid pumped into the well. This data may be correlated with information in the Volume and Rates Calculations table in the Cementing Report. (View→Report) Rates have been decreased to reduce the circulating pressure as a result of checking the Automatic Rate Adjustment box on the Parameter→Job Data dialog. Refer to the Job Data dialog to view the rates specified prior to the rate adjustment. Landmark WELLPLAN 371 Chapter 7: Cementing-OptiCem Analysis Using Foamed Cement In the example we have been using, the circulating pressure exceeds the formation fracture pressure. We have used the automatic rate adjustment option to reduce the circulating pressures. Using foamed cement is another means to reduce the circulating pressures. The Parameter→Foam Data dialog is available only if you check the Use Foam Schedule box on the Parameter→Job Data dialog while using the Wellbore Simulator analysis mode. This dialog lets you describe calculation methods and stages when simulating foam in a cement job. Select Constant or Staged Gas Flow to keep the nitrogen constant for a segment.The foam Type concentrations for density will follow the pressure gradient, and Surfactant, Stabilizer. thus decreases from the bottom to the top of the segment. The longer the segment, the greater the density variance. Select this option if the nitrogen ratio will be adjusted to offset pressure changes and thus hold density more constant. Use this option Click the stage you only with automated nitrogen want to define using pumping equipment. the bottom portion of this dialog. This information is read-only. It is defaulted from the Job Data dialog. In order to foam a segment, The Gas Rate Stage you must check the Foam Number is used to tell box. how many different gas rates are to be used under the Stage Gas option and where each Enter Foam Density and Quality (the volume of the rates are used. percentage of gas in the foam) is calculated. or Enter Quality (the volume percentage of gas in the foam) and Foam Density is calculated. 372 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis The information in this example pertains to the slurry stage. Foam Data Dialog Data Descriptions Calculation Methods Constant or Staged Gas Flow Select this option if nitrogen will be constant for a segment. The foam density follows the pressure gradient, and thus decreases from the bottom to the top of the segment. The longer the segment, the greater the density variance. For depths of 6,000 feet. or less, adjust the nitrogen ratio at least every 1,000 feet; for greater depths, adjust at least every 2,000 feet. Constant Density Select this option if the nitrogen ratio will be adjusted to offset pressure changes and thus hold density more constant. Use this option only with automated nitrogen pumping equipment. Foaming Agents Percentage concentrations of foam stabilizer and foamer other than the standard 1.5 and 0.75% may be entered in the Stabilizer and Surfactant fields. Zero is acceptable, but only in one field at a time. Stages List This is a portion of the fluids list: those that will remain in the annulus. Fluids pumped out or partially pumped and the displacement fluids do not appear in this list. The segment table below shows the foam segments for only one stage at a time. Select the stage you wish to foam by clicking on it to highlight it. You can Landmark WELLPLAN 373 Chapter 7: Cementing-OptiCem Analysis not edit the data listed in the Stages List. This information is defaulted from the Parameter→Job Data dialog. Stage Number Each stage name listed displays its Stage Number in this column. Stage Name This column shows a partial list of fluids that will remain in the annulus. Fluids pumped out or partially pumped and the displacement fluids will not appear in this list. The segment table at the bottom of the dialog shows the foam segments for only one stage at a time. Select the stage you wish to foam. Density The density for this stage, in pounds per gallon. Length The length of this stage, in feet. Stage Name, Top of Stage and In-Place Fluid Length: This data is shown for each stage in the foam job, when the stage is selected from the Stages list above. This information is read-only and defaults from the Parameter→Job Data dialog. Clear button Click to reset all entries in the Segments group. Segments This is a table of foam parameters for each segment of the fluid in the annulus. Displayed segments are for the currently selected stage in the Stages List above. You can break up a stage into segments to vary the foam density or gas rate. The lengths of the segments must add up to the total in-place fluid length for that stage. For constant gas flow method, increment the gas rate stage number when you want a new gas injection rate. To start over on a stage’s segments, click the Clear button. Length The length of this portion of the stage. Foam By selecting this check box, you are indicating that you want to foam this stage. If so, enter the foamed density or quality. Foam Density The foam density for this segment. The field remains inactive unless Foam is checked. Quality Quality is the volume percentage of gas in the foam. Pick a quality or a reduced density. The field remains inactive unless Foam is checked. Gas Rate Stage Number This number is used to tell how many different gas rates are to be used under the Stage Gas option and where each of the rates are used. 374 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis Using the Foam Schedule Use View→Foam Schedule dialog to calculate and view the Foam Pumping Schedule. This dialog lists liquid volume and gas rates of the fluids left in the annulus at the end of the simulation. The calculated hydrostatic pressure for the frac zone and reservoir zones are displayed at the bottom of the table. The frac zone and reservoir zones are specified using the Parameter→Additional Data dialog. Notice that some of these fluids may not be foamed. Some fluids may not appear in this report if they were pumped completely out of the annulus. If an error occurs during the calculation process, an error dialog appears displaying a description of the error. When you finish reading it, click OK. The Error dialog and the Calculate dialog close so you can begin working on solving the source of the error. Landmark WELLPLAN 375 Chapter 7: Cementing-OptiCem Analysis These are design depths (as specified on the Job Data dialog) and may not be the actual depths. Review the View→Final Density and Hydrostatic plot for accurate cement locations. Click Calculate to ensure you are looking at accurate Adjusted Liquid Volume and Adjusted Gas Rate sliders adjust the cement tops results. or placement. These are the calculated Final Gas Rate and Adjusted hydrostatic pressure gradient for Final Gas Rate do not apply the depths of interest specified when you are using constant or on the Additional Data dialog. stage gas flow. Field Descriptions Calculate Click Calculate when you are ready to calculate your data. See the Checking Results section below for tips on how to check results of the calculation. Adjusted Liquid Volume You may enter a value in this field if you wish, or use the sliders to adjust the values displayed. Use the slide bar by clicking it and moving it along the percentage graduation marks. You may also click the slider, or press the Tab key until the slider bar is selected, then use your Right Arrow or Left Arrow keys to adjust the value 376 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis displayed. Use this feature to increase volume or gas cone as needed to correct base hydrostatic calculations. Adjusted Gas Rate You may enter a value in this field if you wish, or use the sliders to adjust the values displayed. Use the slide bar by clicking it and moving it along the percentage graduation marks. You may also click the slider, or press the Tab key until the slider bar is selected, then use your Right Arrow or Left Arrow keys to adjust the value displayed. Use this feature to increase volume or gas cone as needed to correct base hydrostatic calculations. Spreadsheet The spreadsheet section of this dialog displays the calculated foam schedule including volumes, ranges and densities for each segment of the foam job. Top of Fluid The distance from the top of fluid to the Kelly bushing, in feet, for each segment of the foam job. Length The length of the segment, in feet, for each segment of the foam job. Liquid Volume The liquid volume, in barrels, for each segment of the foam job. Adjusted Liquid Volume The adjusted liquid volume, in barrels, for each segment of the foam job. This can be varied as a function of the percentage entered in the Adjusted Liquid Volume field above. Gas Rate The gas rate, or starting rate on ramp N2 jobs, in standard cubic feet per barrel, for each segment of the foam job. Adjusted Gas Rate The adjusted gas rate, in standard cubic feet per barrel, for each segment of the foam job. This varies as a function of the percentage entered in the Adjusted Gas Rate field above. Top/Bottom Density The density in pounds per gallon at the top and bottom of each segment. Final Gas Rate The final gas rate, in standard cubic feet per barrel, for each segment of the foam job. Adjusted Final Gas Rate The final gas rate, in standard cubic feet per barrel, adjusted as a function of the percentage entered in the Adjusted Gas Rate field above. Checking Results To check results of the foam schedule calculation: Landmark WELLPLAN 377 Chapter 7: Cementing-OptiCem Analysis 1. Check the Fluid Animations Schematic to see whether the desired top of cement was achieved, check the Final Positions of Stages table in the reports, or downhole density plot. 2. Check the circulation Pressure and Density-Fracture Zone graph and the Circulation Pressure and Density-Reservoir Zone graphs to see if the density is acceptable. 3. Adjust, rerun, and recheck the job as follows: Checking Results If TOC is.... and ECD is.... then do this: Low Light 1. Increase density or decrease quality. 2. Rerun the Foam Schedule. 3. Use the slider bar (top of Foam Data dialog) to increase the Adjusted Liquid Volume. 4. Click the Calculate button. 5. Check the Fluid Animation Schematic and the Circ Pres and Den plots. Low Acceptable 1. Use the slider bar (top of Foam Data dialog) to increase the Adjusted Liquid Volume. 2. Repeat steps 4 and 5 above. Low Heavy 1. Use the slider bar (top of Foam Data dialog) to increase the Adjusted Gas Rate. 2. Repeat steps 4 and 5 above. Low Light 1. Increase the density or decrease quality. 2. Rerun the Foam Schedule. 3. Repeat steps 4 and 5 above. Acceptable Acceptable Do nothing. 378 WELLPLAN Landmark Chapter 7: Cementing-OptiCem Analysis Checking Results (Continued) Acceptable Heavy 1. Decrease density or increase quality. 2. Rerun the Foam Schedule. 3. Repeat steps 4 and 5 above. Acceptable Heavy 1. Decrease density or increase quality. 2. Rerun the Foam Simulator. 3. Repeat steps 4 and 5 above. High** Light 1. Manually decrease N2 in the Adjusted Start Gas Rate column. 2. If calculation method is constant density, also manually decrease N2 in the Adj. Final Gas Rate column. 3. Repeat steps 4 and 5 above. High** Acceptable 1. Manually decrease liquid volume in the Adj. Liq. Vol. column.* 2. Repeat steps 4 and 5 above. High** Heavy 1. Decrease density or increase quality. 2. Rerun the Foam Simulator. 3. Repeat steps 4 and 5 above. * To estimate the percentage by which to change the volume, use the percentage by which the simulated foamed length differs from the desired length. (If the foamed length 1,500 feet and the desired length is 2,000 feet, increase by 33%.) ** This scenario is unlikely because the Fluid Placement calculations should prevent excessive top of cement. Repeat these steps until you are satisfied with the results. Round the slurry and gas rate quantities before running the Wellbore Simulator. Landmark WELLPLAN 379 Chapter 7: Cementing-OptiCem Analysis References Ravi, K.M., and Sutton, D.L., “New Rheological Correlation for Cement Slurries as a Function of Temperature,” SPE 20449. Shah, Subhash, N., and Sutton, David, L., “New Friction Correlation for Cements from Pipe And Rotational-Viscometer Data,” SPE 19539. 380 WELLPLAN Landmark Chapter 8 Critical Speed The Critical Speed Analysis module was designed to assist with the determination and prediction of damaging downhole vibrations. The analysis begins with a static structural analysis to determine where the drillstring is in contact with the wellbore and to determine what forces are acting on the drillstring. The next step is the vibrational analysis. The program predicts the relative stresses the drillstring will be subjected to based upon a range of rotational speeds (RPMs) input by the user. Critical Speed Course Overview During the Critical Speed segment of your WELLPLAN training you will learn the basic functionality of the Critical Speed Analysis module. The class exercises are designed to mimic a typical Critical Speed Analysis workflow. In the future, you can refer to these workflows to assist you with using WELLPLAN. By the end of the Critical Speed course you will know how to complete the following tasks: q Input required data for the analysis. q Create analysis plots. q Interpret analysis plots to analyze string behavior over a range of operating parameters. q Predict critical rotational speeds that may cause damaging vibrations. q Investigate the effect of changing input parameters on the vibrational response of the string. q Recognize drilling parameters that are likely to cause vibration. Landmark WELLPLAN 381 Chapter 8: Critical Speed Critical Speed: An Introduction What is the Critical Speed Module? The Critical Speed Analysis module is used to identify critical rotary speeds and areas of high stress concentration in the drillstring. The analysis uses an engineering analysis technique called Forced Frequency Response (FFR) to solve for resonant rotational speeds 382 WELLPLAN Landmark Chapter 8: Critical Speed Resonance can occur when a drillstring’s natural vibration is subjected to a forced vibration. Resonance is an increase in amplitude that results when a drillstring is exposed to a periodic force or displacement (excitation) whose frequency is equal to, or very close to the natural frequency of the system. Resonance is nearly always accompanied with severe high dynamic stresses that can cause drillstring damage or failure. The Critical Speed Analysis module indicates resonant frequencies for a drillstring rotating in a wellbore, as well as non- rotating steerable assemblies. The effects of hole angle, curvature, collar size, contact locations, and BHA displacement due to rotational friction effects can be modeled. Drill string rotation will affect the results of this analysis, to some degree, due to additional torque at the contact points that are generated due to friction forces. Critical Speed Limitations A rotating drillstring is subject to intermittent contact, impact, and friction effects as well as many other highly nonlinear and transient phenomena. Since the Critical Speed Analysis module assumes cyclic behavior, transient effects typical for drillstring dynamics cannot be modeled. The analysis assumes all drillstring components are free of stress fractures. Ideally, this type of analysis is run along with downhole sensors, or at the least with careful surface observations. Isolating and identifying the principal excitation mechanism responsible for drillstring vibrations has proven to be challenging. The literature contains many studies undertaken to acquire and analyze experimental and field-derived data to determine the dynamic characteristics of drillstring systems. Many excitation mechanisms have been identified, including bit forces, stabilizer forces, mass imbalances, and walk and whirl mechanisms. It is important to realize that the Critical Speed Analysis module does not provide an exact solution for critical frequencies. The results from the Critical Speed Analysis are relative stresses, indicating those frequencies that are likely to cause damaging vibrations. The Critical Speed Analysis module can be used prior to drilling, or can be use in conjunction with downhole sensors. Vibration control is a multi-step process. It involves planning and analysis, monitoring during drilling, and interpreting control through observations. Landmark WELLPLAN 383 Chapter 8: Critical Speed Workflow The following steps are designed to be a general guide to the steps involved in using the Critical Speed Analysis module. This workflow is not intended to suggest that you must follow these steps when using the module. There are certainly other workflows that may meet your analysis requirements. q Open the Case. (File →Open Case) If you have created a new case, save the case. (File →Save As) q Select the Critical Speed Analysis module by clicking . q Enter general information about the case. (Case →General) q If this is an offshore well, enter water depth and well type. (Case →Offshore) If this isn’t an offshore well, you won’t be able to access this dialog. q Define the wellbore. (Case →Wellbore) q Define the workstring. Use the same dialog to define all workstrings (drillstrings, tubing, liners, and so forth) (Case →String) q Enter deviation (survey) data. (Case →Deviation→Survey Editor) q Define the fluids used. You must define the fluid rheological properties, select a rheology model, and specify the temperature. You can define as many fluids as you want. Only one fluid can be used at a time. (Case →Fluid Editor) q Optional Step: Most of the time you will want to use the default values for the mesh. Rarely will you need to change this information. (Case →Mesh Zone) q Define the analysis parameters. (Parameter→Critical Speed Analysis Parameters) q Analyze the results. First, determine the critical rotational speeds. (View→Rotational Speed Plots→Resultant Stresses) Next, determine where in the string the greatest relative stress is occurring at the critical rotational speeds. 384 WELLPLAN Landmark Chapter 8: Critical Speed (View→Position Plots→Resultant Stresses) You may also want to determine what type of stress is causing the large relative stresses. (View→Position Plots→Stress Components) Landmark WELLPLAN 385 Chapter 8: Critical Speed Using Critical Speed Starting the Critical Speed Module There are two ways to begin the Critical Speed Analysis module: l Select Critical Speed from the Modules menu. l Click the button. Opening the Case In this section of the course, we will be analyzing the Case ‘Landmark 1’ in the Project ‘Wellplan 6 Example’ and Well ‘DEMO’. Open this Case now by using File→Open Case and selecting the appropriate Project, Well and Case. Entering Case Data Like all WELLPLAN modules, Critical Speed uses the information input on the Case menu. Entry of almost all of this information is discussed in the Basics chapter of this manual. Please refer to “Entering Case Data” on page 40 of the Basics chapter of this manual if you have questions concerned with the General dialog, Offshore dialog, Wellbore Editor, String Editor, Survey Editor, or Fluid Editor. Specify the Finite Element Mesh Normally you will use the default values as shown below. You may consider changing the mesh if you are particularly interested in what is happening at a particular section of the workstring. Otherwise, the defaults provide adequate analysis of most situations. The information entered on this dialog is used to divide the string up into small portions (called elements) prior to analysis. The Finite Element analysis (FEA) method used in Critical Speed analyzes small portions initially, and then combines the individual analyses into an complete analysis for the entire string. Please refer to “Supporting Information and Calculations” on page 422 of the Bottom Hole Assembly chapter of this manual for more information about FEA. 386 WELLPLAN Landmark Chapter 8: Critical Speed Use the default values as displayed unless you are familiar with FEA and are particularly interested in a section of the string. To understand how the Mesh Zone is used, assume you have an 8" collar located in Zone 1. The maximum element length in Zone 1 for an 8" collar would be: 8 inches X 20 (default for Aspect Ratio 1) = 160 inches = 13.3 ft. An exception to this is in the bottom 12 feet of Zone 1 where there is a 3-foot limit for element length. The 3-foot limit is included because the drillstring closest to the bit has a significant impact on the behavior of the bottom hole assembly. Landmark WELLPLAN 387 Chapter 8: Critical Speed Defining Analysis Parameters Use the Parameter→Critical Speed Analysis Parameters dialog to input parameters needed to perform the critical speed calculations. Refer to text below for field definitions. Field Definitions Torque at Bit Type the actual torque at the bit. Obtain typical bit torque values from the bit manufacturer, or provide an estimate based on your own experience. Weight on Bit Type the actual weight applied at the bit, not the surface weight that is slacked off. Steering Tool Orientation Type the orientation of the steering tool (scribe line) relative to the high side of the hole, measured clockwise from the high side. This is used to orient the bend angle relative to the high side of the hole. Starting Speed, Ending Speed A critical speed analysis will be performed at every Speed Increment within the range specified by the Starting Speed and Ending Speed fields. Speed Increment Type the range and the speed increment you want. Note: Calculation time increases as the number of speeds analyzed increases. To reduce execution time, reduce the number of speeds being analyzed at one time. Excitation Frequency Factor Type the rate you want the forcing function to be applied (number of excitation per revolution). A general rule of thumb is to use 3.0 388 WELLPLAN Landmark Chapter 8: Critical Speed for tricone bits and 6.0 to 9.0 for PDC bits. The nature of forcing functions is still an area of study in the industry. Mesh Begins at Dist. From Bit, Max Total Length of Mesh Normally, you will type values of 0.0 (zero) and 99999.9 for the Mesh Begins At Depth From Bit and Max Total Length of Mesh, respectively, in order to analyze the entire string starting at the bit (or as much as can be meshed by the number of nodes available). If you want to study an limited portion of the string, type a smaller range. Use measured depth to estimate the distance in feet.If you get an error message indicating an “Non Converged Solution,” this means the critical speed analysis was unable to solve the structural solution, usually because the of a complex drillstring (many small components) and hole geometry. If this happens, shorten the mesh length, and run the analysis again. Dynamics Check this box to turn on the calculation of the nodal torque due to friction. The nodal torque affects the initial static solution of the displaced shape of the BHA. If you don’t check this box, the only torque that will be used is the torque you entered for Torque at Bit. Specify the Boundary Conditions Use the Parameter→Boundary Condition Options dialog box to determine the physical constraints on the top and bottom nodes of the mesh. Use the default values as presented here, unless you are familiar with Finite Element Analysis methods. Fix w/Axial Slider prevents all movement except for sliding movement along the longitudinal axis of the string. Fix Axial prevents sliding movement along the longitudinal axis of the string, but allows all other types of movement. Landmark WELLPLAN 389 Chapter 8: Critical Speed Calculating Results Calculations will be performed automatically when you select a plot from the View menu. A typical critical speed analysis consists of an initial “frequency sweep,” in which the drillstring is analyzed over a user-specified range of operating speeds. The program repeatedly analyzes the drillstring by incrementally stepping though the given range. At each step the program computes the excitation frequency for that step from the current rotational speed (RPM) and the excitation factor. It then applies the excitation to the drillstring at the computed frequency and solves for the response in the entire model. For this analysis, response means any component of displacement, force, or stress. The maximum response at each step is saved. After the entire range has been analyzed, the maximums can be plotted against the operating speed range. These plots are then used to determine the critical operating speeds for the drillstring or assembly. Once the critical speeds are determined, the analysis can be repeated at each critical speed and the response of the total drillstring model can be examined. This type of analysis is used to determine the exact nature of the resonant behavior at a particular critical speed. Analyzing the Results All critical speed analysis results are presented as graphs, and can be selected from the View menu. What are the Critical Rotational Speeds? You can determine the critical rotational speeds by reviewing the Equivalent Resultant Stress curve on the View→Rotational Speed Plots→Resultant Stresses plot. It is important to remember that the stress values are relative stresses and not actual stresses. The stresses are relative in magnitude to each other also. You cannot determine from the plot what the actual stress is. You can only compare relative magnitudes. 390 WELLPLAN Landmark Chapter 8: Critical Speed For example: If two stresses are calculated to be 5,000 and 10,000 psi, the stresses may not be exactly equal to the calculated value. Because the stresses are relative in magnitude, the stresses may really be 4,000 and 8,000 psi. All peaks represent stresses above and beyond steady state stresses caused by vibrations. They are relative to the magnitude of the forcing function used and should be used only to assist with the location of critical rotating speeds. The forcing function is a periodic displacement or force (the Critical Speed Analysis module uses displacement) at a point on the drillstring that is assumed to occur a regular number of times per revolution. The forcing function (displacement) can be lateral, axial, or torsional. Referring to the following Maximum Relative Resultant Stress plot, you can see the large peaks of relative stress at certain rotational speeds. You should avoid the rotational speeds associated with a large relative stress. Make a note of the critical rotational speeds. You will use them in the next step of your analysis. The peak at 74 rpm indicates that this is a critical rotational frequency. This frequency should be analyzed further. Note that you cannot determine the actual resultant stress by reviewing this plot. You can only determine that the stresses at 74 rpm are greater than the stresses at other rpms. Where in the BHA are the Large Relative Stresses Occurring? Now that you know what rotational speeds are causing large relative stresses, you may want to know where in the bottom hole assembly (BHA) these stresses are occurring. Use the Landmark WELLPLAN 391 Chapter 8: Critical Speed View→Position Plots→Resultant Stresses plot to determine where in the BHA the large stresses are occurring. At 74 rpm, the maximum equivalent stress is acting on the bottom hole assembly 31 feet from the bit. Use the slider bar to change the rotational speed you want to analyze. Refer to the Case→String Editor to determine what component is located 31 feet from the bit. What Kind of Stress is Causing the Large Relative Stress? You may want to know what type of stress (axial, bending, torsional, shear) is causing the large relative resultant stresses to occur in a certain part of the BHA. Use the View→Position Plots→Stress Components plot. Bending stress is the most significant stress acting on the bottom hole assembly 31 feet from the bit while rotating at 74 rpm. 392 WELLPLAN Landmark Chapter 8: Critical Speed How Do I View the Large Relative Stress at Any Position on One Plot? We have been using one plot to tell us what rotational speeds have a large relative stress and then referring to a position plot to tell us where in the bottom hole assembly these stresses are occurring. You can use the View→3D Plots→Resultant Stresses→Equivalent plot to view this information on one plot if you prefer. Read Distance from Read Rotational Click and hold down Bit on this axis. Speed on this axis. the left mouse button anywhere on the plot and then move the mouse to rotate the plot. Read the Equivalent Stress on this axis. Landmark WELLPLAN 393 Chapter 8: Critical Speed Supporting Information and Calculations Structural Solution The Critical Speed Analysis module begins by performing a structural solution to determine the displaced shape of the drillstring and the forces acting on it. The structural solution is accomplished through the use of the mathematical Finite Element Analysis method. The static structural solution is completed to determine where the drillstring is in contact with the wellbore. This information is passed on to the vibrational analysis segment of the analysis. Any contact points found during the structural solution are assumed to remain in contact during the vibrational analysis. Other points of contact between the string and the wellbore may occur due to vibration. These contact points may lead to displacements outside of the wellbore. In reality, displacements outside of the wellbore do not occur. This is a limitation in the analysis. As a result of this limitation, the analysis predicts a relative critical frequency (RPM), and does not model or predict the actual magnitude of a critical frequency. The steps performed in the structural solution analysis step are the same as those performed in the WELLPLAN Bottom Hole Assembly analysis module. The only exception is that the Critical Speed Analysis module meshes the drillstring into 150 nodes. (The Bottom Hole Assembly Analysis module will mesh the BHA into 40 nodes.) Refer to the Bottom Hole Assembly module chapter in this manual for more details concerning the structural solution. Vibrational Analysis Following the completion of the structural solution, the vibrational portion of the analysis is begun. After the shape of the drillstring is determined and the structural solution has been performed, the Critical Speed Analysis module calculates the critical frequencies, or RPMs. The critical frequencies are determined from the response of the BHA to some user specified harmonic excitation usually, but not limited, to the bit. The Critical Speed Analysis module assumes that at a critical rotational speed, or RPM, excitations at the bit, stabilizer, or other contact points cause large displacements and stresses elsewhere in the drillstring. Because the Critical Speed Analysis module is a harmonic 394 WELLPLAN Landmark Chapter 8: Critical Speed vibration analysis, it does not model the reaction of the drillstring if it is rotating about an axis that is not centered on the drillstring axis (bit whirl). The Critical Speed Analysis module solves for a range of frequencies to determine the sensitivity of the BHA to the excitation frequency. Because the analysis applies the boundary conditions only during the static structural solution, it may yield displacements outside of the wellbore during the vibrational analysis. The Critical Speed Analysis module is not a transient analysis, and does not solve the analysis related to time. As a result, any contact points occurring as a result of the vibrational analysis are allowed to penetrate the wellbore. The full transient dynamic response analysis of any non-linear finite element model involves the finite integration of the equations of motion found in Equation 1. In Equation 1, P(t) is a vector quantity indicating the periodic displacement at a point on the drillstring that occurs at a regular number of times per revolution. This displacement (or force) can be lateral, axial, or torsional. {P(t)} = {I(u,t)} + [C]{ú(t)} + [M]{Ü(t)} (equation 1) where: {P(t)} = Applied Load Vector (or forcing function) at time t {u(t)} = Displacement Vector at time t {I(u,t)}= Internal Force Vector at time t and Displacement State {u} [C] = Damping Matrix [M] = Mass Matrix {} indicates a vector quantity [] indicates a matrix quantity () indicates differentiation with respect to time t To utilize this equation for solving drilling mechanics problems, it must be formulated to include the following factors common to drilling. • The need for large displacement and finite rotation beam theories in modeling drillstring and BHA components • Dealing with intermittent contact and the friction effects involved • The need to model a tortuous 3D curved wellbore surface • Representing the structural behavior of certain drillstring components (motors and so forth) Landmark WELLPLAN 395 Chapter 8: Critical Speed The approach utilized in the analysis solves a linearized form of the above equation for the case of vibration in which all displacements and forces are varying harmonically in time at the same frequency. In order to develop the harmonic formula, two assumptions are made: • First, it is assumed that the response is at the same frequency as the excitation, but not necessarily the same phase. • Second, it is assumed that the excitation is a function and response of the sin and cosine terms at the same phase. Since the analysis assumes cyclic behavior, transient effects, such as impact forces that may have a significant impact on the service life of a component, can not be modeled with the Critical Speed module. The solution is based upon an imposed load or force vector excitation {P}, and it is assumed the BHA is subjected to a harmonically varying form of the excitation {P} given by: {P(t)} = {Ps}sin ωt + {Pc}cos ωt (equation 2) which yields a resulting steady state displacement response of: {u(t)} = {us} sin ωt + {uc} cos ωt (equation 3) The angular frequency (ω) of the excitation is directly related to the rotary speed through the use of an excitation factor. The excitation factor designates how many times per revolution a given excitation occurs. Combining the three previous equations and implementing concepts from complex vector algebra, it is apparent that the steady state displacement field arising from the applied harmonic loading can be determined by solving for the solution of the linearized system of complex force-displacement relation given by: {Pc} + i{Ps} = ([J] - ω2[M] + iω[C])({uc} + i{us}) (equation 4) where: i = −1 [J] = Jacobian matrix (contains the effects of contact, stress stiffening and friction) [M] = Mass matrix [C] = Damping matrix 396 WELLPLAN Landmark Chapter 8: Critical Speed During the vibration portion of the analysis, the previous equation is solved for a range of operating (RPM) speeds. At a critical rotary speed, small forced excitations at the point of application will cause large displacements and stresses elsewhere in the drillstring. Therefore, ωcr is said to locate a point of structural instability of the BHA. The Critical Speed Analysis module generates many graphics to illustrate this phenomena. Mass Matrix The mass matrix implemented in the Critical Speed Analysis module is a lumped mass matrix. From the composition of the matrices, it is evident that the material component descriptions (ID, OD, weight, material), and fluid descriptions are important data for correctly determining vibrational response. In the previous equation, the mass matrix is denoted by [M], and contains terms based on the following four classes of effects: l Structural - This is the primary mass matrix, and is based on the dimensions and material of the drillstring. l Fluid - Additional term included to account for the weight of the fluid inside the drillstring. l Inertial - Includes the effects of acceleration of mud outside the drillstring. l Nonstructural mass - Includes miscellaneous masses that may be attached to the drillstring and are not accounted for in any other way. Damping Matrix The Critical Speed Analysis module includes damping in predicting the response of the drillstring to the specified excitations. Damping primarily limits the magnitude of the response to the excitation. An important implication of including damping in the model is that while the response of the BHA will be at the same frequency as the excitation, it may not be in phase with it. Damping includes the effects of interaction with the formation, drilling fluid effects, inertial effects of acceleration of mud outside the drillstring and mass damping produced by the BHA structure. Landmark WELLPLAN 397 Chapter 8: Critical Speed To account for the damping, or energy losses that drillstring vibration is subjected to, the Critical Speed includes the following three damping mechanisms. l Structural Damping - Accounts for energy losses due to mechanical means. l Fluid Damping - Accounts for energy losses due to fluid movement on the drillstring. This damping does not use fluid viscosity, and applies to the axial and torsional directions only. l Lateral Fluid Damping - Accounts for energy losses due to viscous fluid damping, and is applied to lateral direction only. This type of damping is based on the work done by Chen (refer to the Reference section) and uses flow equations for fluid moving around a cylinder in a confined space. The damping matrix terms are a function of beam element length, outer diameter, and constant fluid damping coefficients. Discrete fluid damping coefficients are also assigned for lateral, axial, and torsional DOF. All damping coefficients are defaulted and are not user input items. Including damping is an important part of the vibrational analysis. Referring to Equation 4, if the damping matrix is removed, the equation is simplified. However, if damping is not included, the plots of amplitude vs. frequency cause the critical states to appear as extremely steep and relatively narrow spikes of infinite amplitude. A steep, narrow spike could mislead a user into concluding that the analysis calculates an exact value for the critical frequency (RPM). In reality, the analysis can only predict a range of critical frequencies, but can not provide an exact critical frequency. Excitation Factors The frequency of the excitation mechanism is designated by the use of the excitation factor. This factor is simply the number of times the excitation is applied for each revolution of the drillstring. Although excitations are usually at the bit, this analysis can model excitations at other locations. The Critical Speed Analysis module can also model multiple excitations at multiple locations. These excitations can be out of phase with one another, but they will all be assumed to be excited at the same number of excitations per revolution. This can be a 398 WELLPLAN Landmark Chapter 8: Critical Speed problem if a tricone bit (normally 3 excitations/revolution) is combined with a four blade stabilizer (perhaps 4 excitations/revolution). Experience has shown the following excitation factors: l Tricone Bits: EF = 3, as expected from the three lobed geometry l PDC Bits: EF for PDC Bits vary depending on the bit design. There is no specific rule for selecting the EF for PDC bits. However a general rule obtained from laboratory experience is: EF= (n)(#Blades) + 1; where n = 1 or 2 Landmark WELLPLAN 399 Chapter 8: Critical Speed The following table presents several primary and secondary excitation factors that may occur during drilling. For more information concerning this information, refer to the references presented at the end of this chapter. Physical Primary Secondary Mechanism Excitation(s) Excitation(s) Mass Imbalance 1 X RPM Lateral 2 X RPM Axial or or Bent Pipe 2 X RPM Torsional or 2 X RPM Lateral Misalignment 1 X RPM Lateral or 2 X RPM Axial or 2 X RPM Lateral 2 X RPM Axial Tricone Bit 3 X RPM Axial 3 X RPM Torsional or 3/2 X RPM Lateral Very Soft 1,2,3,4,5, X RPM Axial, Formation, Low Torsional, Lateral WOB, Causing a Loose Drillstring Rotational Walk dh /(dh - dd) X RPM Lateral 2(dh (dh -dd)) RPM Axial or (precessional) 2(dh (dh -dd)) RPM Torsional Rotational Walk dd /(dh - dd) X RPM Lateral 2(dd (dh -dd)) RPM Axial or (backward whirl) 2(dd (dh -dd)) RPM Torsional Non synchronous (0.8 to 1.0)(dh(dh - dd)) X RPM (0.6 to 2.0)(dh(dh - dd)) X Walk or Whirl Lateral (0.6 to 2.0)(dh(dh - dd)) RPM Axial or X RPM (0.6 to 2.0)(dh(dh - dd)) X RPM Torsional Drillstring Whip RPM Harmonics (1X, 2X, 3X) RPM Harmonics Axial, Lateral Torsional 400 WELLPLAN Landmark Chapter 8: Critical Speed References Field, D.J., DRD Corp., Swarbrick, A.J., Halliburton MWD, and Haduch, G.A., DRD Corp., “Techniques for Successful Application of Dynamic Analysis in the Prevention of Field-Induced Vibration Damage in MWD Tools,” SPE #25773, 1993. Apostal, M.C., Haduch, G.A., and Williams, J.B., DRD Corp., “A Study to Determine the Effect of Damping on Finite-Element-Based, Forced- Frequency-Response Models for Bottomhole Assemble Vibration Analysis”, SPE #20458, 1990. Besaisow, A.A. and Payne, M.L., ARCO Oil and Gas Co., “A Study of Excitation Mechanisms and Resonances Inducing BHA Vibrations”, SPE #15560, 1986. Nicholson, J.W., Shell Research B.V., “An Integrated Approach to Drilling Dynamics Planning, Identification, and Control”, IADC/SPE #27537, 1994. Defourny, P., Security DBS, and Abbassian, F., BP Exploration, “Flexible Bit: A New Anti-Vibration PDC Bit Concept”, SPE #30475, 1995. Gallagher, J., Baker Hughes INTEQ, Waller, M., Shell (U.K.) E&P, and Ruszka, J., Baker Hughes INTEQ, “Performance Drilling: A Practical Solution to Drillstring Vibration”, IADC/SPE 27538, 1994. Behr, S.M., Warren, T.M., Sinor, L.A., Brett, J.F., Amoco Production Co., “Three-Dimensional Modeling of PDC Bits”, SPE #21928, 1991. Behr, S.M., Warren, T.M., Brett, J.F., Amoco Production Co., “Bit Whirl: A New Theory of PDC Bit Failure”, SPE 19571, 1989. Dykstra, M.W.; Chen, D. C-K.; Warren, T.M.; Azar, J.J., “Drillstring Component Mass Imbalance: A Major Source of Downhole Vibrations”, SPE #29350, 1996. Landmark WELLPLAN 401 Chapter 8: Critical Speed 402 WELLPLAN Landmark Chapter 9 Bottom Hole Assembly The Bottom Hole Assembly module was designed to predict the directional drilling performance of a bottom hole assembly. The module can provide an accurate representation of the forces acting on the assembly as it exists in the wellbore. This type of analysis can be useful for explaining unexpected performance or for determining the causes of tool failures. In addition, the module can solve a “drillahead” scenario to represent the expected behavior of the bottom hole assembly as it drills new hole. Bottom Hole Assembly Course Overview During the Bottom Hole Assembly segment of your WELLPLAN training you will learn the basic functionality of the Bottom Hole Assembly module. The class exercise and workflow are designed to follow a typical workflow using the module. In the future, you can refer to these workflows to assist you with using WELLPLAN. By the end of the Bottom Hole Assembly course you will know how to complete the following tasks: q Input required data for the analysis. q Create analysis plots and report. q Interpret analysis plots to analyze string behavior over a range of operating parameters. Landmark WELLPLAN 403 Chapter 9: Bottom Hole Assembly Bottom Hole Assembly Analysis: An Introduction What is the Bottom Hole Assembly Module? The Bottom Hole Assembly module analyzes a bottom hole assembly (BHA) in a static “in-place” condition or in a “drillahead” mode. Many different factors influence the behavior of a bottom hole assembly. These factors include more controllable parameters such as WOB, and drillstring component size and placement, as well as less controllable items such as formation type. Because the performance of a bottom hole assembly is impacted by such a wide and varied range of parameters, predicting the behavior of a bottom hole assembly can be very complex. Engineers in other fields have often relied on the Finite Element Analysis Method to solve complex problems. The Finite Element Analysis (FEA) method solves a complex problem by breaking it into smaller problems. Each of the smaller problems can then be solved much easier. The individual solutions to the smaller problems can be combined to solve the complex problem. Depending on the number of elements (smaller problems) that the complex structure (overall problem) is comprised of, the solution can become very laborious. Fortunately, the combination of the increasing speed of computing power and creative mathematics have significantly simplified FEA analysis. Because a bottom hole assembly is composed of many different elements of varying dimensions, it lends itself quite well to the FEA method. The following sections describe the major steps performed by the Bottom Hole Assembly module while solving for an “in-place” solution, as well as a “drillahead” prediction. For more technical information, refer to “Supporting Information and Calculations” on page 422. Why Should I Use the Bottom Hole Assembly Module? There are many times where the Bottom Hole Assembly module can be useful. Among these are: l Analyze the contact forces and displaced shape of a bottom hole assembly including the bit tilt, side forces, and wellbore contact points. 404 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly l Study previous directional failures through analysis of contact forces on tools. l Predict the directional behavior (including build, walk, and drop) of a bottom hole assembly as it drills ahead through a specified interval. l Predict the transient effect when new assembly is run in hole. l Adjust operating parameters to affect bottom hole assembly performance. l Study effects of bent assemblies, collar size, stabilizer placement, eccentric stabilizers, stabilizer wear, hole enlargement, operating parameters for optimal performance. l Select proper bent sub to achieve desired build or drop rate. l Estimate the additional torque drawn from a motor due to lateral forces at bit. l Determine the downhole mechanism controlling the bottom hole assembly. l Determine the orientation of a bottomhole assembly (0 - 180 degrees left or right of high side) for achieving optimum performance in a well deflection scenario. l Compare a rotary versus steerable assembly performance for a given well trajectory analysis. l Optimize the design of a steerable system through modeling of number of bends and eccentric contact points in the bottom hole assembly. Bottom Hole Assembly Module Limitations The Bottom Hole Assembly module does not model formation dip. Landmark WELLPLAN 405 Chapter 9: Bottom Hole Assembly Workflow The following steps are designed to be a general guide to the steps involved in using the Bottom Hole Assembly module. This workflow is not intended to suggest that you must follow these steps when using the module. There are certainly other workflows that may meet your analysis requirements. q Open the Case. (File →Open Case) If you have created a new case, save the case. (File →Save As) q Select the Bottom Hole Assembly module by clicking . q Enter general information about the case. (Case →General) q If this is an offshore well, enter water depth and well type. (Case →Offshore If this isn’t an offshore well, you won’t be able to access this dialog.) q Define the wellbore. (Case →Wellbore) q Define the workstring. Use the String Editor to define all workstrings (drillstrings, tubing, liners, and so forth). (Case →String Editor) q Enter deviation (survey) data. (Case →Deviation→Survey Editor) q Define the fluids used. You must define the fluid rheological properties, select a rheology model, and specify the temperature. You can define as many fluids as you want. Only one fluid can be used at a time. (Case →Fluid Editor) q Optional Step: Most of the time you will want to use the default values for the mesh. Rarely will you need to change this information. (Case →Mesh Zone) q Define the analysis parameters. (Parameter→Analysis) q Analyze the results. Using View→Report→BHA you can analyze the expected build/drop and walk rates for the bottom hole assembly. You can also analyze the contact forces acting on the BHA, which may assist you with determining why the bottom hole assembly is performing as it is. 406 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly Using Bottom Hole Assembly Analysis Mode Starting Bottom Hole Assembly Analysis There are two ways to begin the Bottom Hole Assembly module: l Select Bottom Hole Assembly from the Modules menu. l Click . In this class example, we will use the case “9 5/8" casing” in the Guided Tour project, well named Tour #1. Please open this case. Entering Case Data Like all WELLPLAN modules, Bottom Hole Assembly uses the information input on the Case menu. Entry of almost all of this information is discussed in the Basics chapter (2) of this manual. Please refer to the Basics chapter of this manual if you have questions concerned with the General dialog, Offshore dialog, Wellbore Editor, String Editor, Survey Editor, or Fluid Editor. Specify the Finite Element Mesh Normally you will use the default values as shown below. You may consider changing the mesh if you are particularly interested in what is happening at a particular section of the workstring. Otherwise, the defaults provide adequate analysis of most situations. The information entered on this dialog is used to divide the string up into small portions (called elements) prior to analysis. The Finite Element analysis (FEA) method used in Bottom Hole Assembly analyzes small portions initially, and then combines the individual analyses into an complete analysis for the entire string. Landmark WELLPLAN 407 Chapter 9: Bottom Hole Assembly Use the default values as displayed unless you are familiar with FEA and are particularly interested in a section of the string. You may want to reduce the element size in areas you are particularly interested in. To understand how the Mesh Zone is used, assume you have an 8" collar located in Zone 1. The maximum element length in Zone 1 for an 8" collar would be: 8 inches X 20 (default for Aspect Ratio 1) = 160 inches = 13.3 ft. An exception to this is in the bottom 12 feet of Zone 1 where there is a 3-foot limit for element length. The 3-foot limit is included because the drillstring closest to the bit has a significant impact on the behavior of the bottom hole assembly and a smaller element size better models the behavior in this portion of the string. Analyzing a Static Bottom Hole Assembly Static in-place analysis of the bottom hole assembly can be useful in determining the contact forces and displaced shape of a bottom hole assembly, including bit tilt, side forces, and wellbore contact points. This may be helpful in analyzing previous directional failures through analysis of contact forces on tools. Defining Analysis Parameters for Static Analysis Use Parameter→Analysis to input parameters needed to perform the calculations. Do not mark the Enable Drillahead check box at this time because we are analyzing the bottom hole assembly at the current depth. 408 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly Later we will analyze the forces acting on the bottom hole assembly in a “drillahead” scenario. For information regarding data required for this dialog, refer to the following text. 7 Parameters Torque at Bit Type the actual torque at the bit. Obtain typical bit torque values from the bit manufacturer, or provide an estimate based on your own experience. Weight at Bit Type the actual weight applied at the bit. Weight on bit is the compressive axial load that is applied to the formation by the bit face. It is the difference between the net weight of the entire drillstring and the resulting reduced weight when the bit is resting on bottom. Rotary Speed Type the rotating speed of the drillstring and bit once steady state conditions are reached. For rotary assemblies, type the rotating speed of the drillstring. For hydraulic motor assemblies where the drillpipe does not turn, type the rotating speed of the bit. The rotary Landmark WELLPLAN 409 Chapter 9: Bottom Hole Assembly speed is used in the lateral penetration model. It does not effect the static structural solution of the bottom hole assembly. Enable Drillahead Box Check this box to solve a “drillahead” scenario to represent the expected behavior of the bottom hole assembly as it drills new hole. The “drillahead” solution advances the bit depth, in 5-foot intervals, through the drill interval specified below. At each of the 5-foot intervals, a static solution is performed. The drillahead solution assumes the following: • The bit will drill in the direction it is pointed. • The bit will cut sideways due to the presence of side forces generated in the inclination and direction axes. • The formation has isotropic rock properties. Drillahead Steering Tool Orient Steering tool orientation is the orientation of the steering tool (scribe line) relative to the high side of the hole, measured clockwise from the high side. The tool orientation is used in conjunction with the Tool Reference to determine the orientation of the bend, relative to the high side of the hole. Note: A steering tool must be present in the drillstring in order to enter a tool orientation. Refer to the Basics chapter (2) of this manual for help with entering steering tools. Drill Interval Drill interval is the total measured depth distance that the current bottom hole assembly will drill ahead. Usually, 100 to 200 feet is sufficient to determine the directional behavior of the bottom hole assembly. A minimum value of 100 feet is recommended. Overgauge Overgauge is the amount of washout expected as the bottom hole assembly is drilling. This effect can be modeled without having to change the hole size on the Wellbore Editor. Record Interval Record interval is the distance at which the survey points will be generated for the final output. Bit Coefficient The bit coefficient is a number between 0 and 100 that indicates the efficiency at which a drill bit will cut sideways. The typical range for roller bits is 20-80, 80 being used for soft formation bits and 20 for hard formation bits. A bit coefficient of 0 means the bit does not cut sideways, yielding a trajectory based solely on bit tilt. Rarely will a bit attain an efficiency of 100. Refer to “Supporting 410 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly Information and Calculations” on page 422 of this chapter for more information. Formation Hardness The formation hardness is a number between 0 and 60 which is used in the lateral ROP model to resist the bit side cutting capability. Refer to “Supporting Information and Calculations” on page 422 of this chapter for more information. Rate of Penetration The rate of penetration is the speed at which the drillstring is drilling the hole. Dynamics Box Check to turn on the calculation of the nodal torque due to friction. The nodal torque affects the initial static solution of the displaced shape of the bottom hole assembly. If you do not check this box, the only torque that will be applied to the string is the specified torque at bit. Analyzing Results for the Static (in-place) Position First we are going to analyze the current position of the bottom hole assembly. We will investigate the position of the bottom hole assembly in the wellbore and we will determine the side forces acting on the bottom hole assembly where it is in contact with the wellbore. Later we will analyze the bottom hole assembly as it drills ahead. Plots Two plots are available for analysis. The Displacement plot allows you to determine how the bottom hole assembly is lying in the wellbore. The Side Force plot tells you the side force acting on the bottom hole assembly as it lies in the wellbore. Displacement Plot The View→Displacement plot displays the displacement from the centerline versus distance from bit. Three measures of displacement are used: • Inclination - the displacement of the analyzed portion of the drillstring from the wellbore centerline in the inclination plane • Directional - the displacement of the analyzed portion of the drillstring from the wellbore centerline in the direction plane • Clearance - the displacement of the analyzed portion of the drillstring from the wellbore centerline Landmark WELLPLAN 411 Chapter 9: Bottom Hole Assembly A positive value for Direction indicates the string displacement from the wellbore centerline is towards the right side of the wellbore. A clearance of zero A negative value for Inclination indicates the string is indicates the string displacement lying along the wellbore. from the wellbore centerline is towards the low side of the wellbore. Side Force Plot The View→Side Force plot displays the calculated side force (at each node analyzed) versus distance from bit. This information is also displayed in table form in the BHA Forces section of the report. The maximum side force is at the bit. About 65 feet from the bit, the side force is close to 1000 lbs. Report Options The Report Options dialog is used to specify what additional information will be included on the report. Using this dialog, you can include or exclude much of the information defining the case you are analyzing. 412 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly Using the Report The BHA report (View→Report→BHA) contains information regarding the forces acting the bottom hole assembly and the resulting displacements. The BHA report provides information concerning the forces acting on each element and node as well. What is Happening at the Bit? The BHA report includes a section that indicates the bit tilt in both the inclination and direction planes. This information pertains to the bit only. It is possible to have a negative bit tilt, yet build angle. If this should occur, it is probable that the bit is momentarily tilted downward, and that the assembly is influenced by a positive side force. Always consider all the information presented when analyzing a bottom hole assembly performance. What are the Forces Acting on the Bottom Hole Assembly? The following is an excerpt from the BHA report. From this portion of the BHA report you can view a table of the forces acting on the bottom hole assembly. Force information is useful in determining where the bottom hole assembly is in contact with the wellbore along with the corresponding side force at the contact point. This can be helpful if an assembly is not building or dropping as expected. Perhaps there is no contact between stabilizers for a build assembly, or the contact point is not in the proper location. The BHA Forces information may also be useful in determining areas where casing wear may become a problem. Look for areas of contact in the cased hole section. The Bottom Hole Assembly module will not determine if casing wear is a problem, only that the bottom hole assembly is in contact with the inside of the casing. Landmark WELLPLAN 413 Chapter 9: Bottom Hole Assembly If you do not check the Dynamics box on the Analysis Parameters dialog the torque You can determine the contact is always equal to the value forces acting on any portion of for torque at bit that you the string that was analyzed. specified. Where is the Bottom Hole Assembly Located in the Wellbore? The following is an another excerpt from the report. From this portion of the report you can view a table representing how the bottom hole assembly is lying in the wellbore. 414 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly Clearance is the minimum This information is distance also available in the between the Displacement plot drillstring and you viewed earlier. the wellbore. What Force and Moment is Acting at Each Node? The Element Forces Table from the BHA Report contains information regarding the magnitudes of the forces and moments (associated with each degree of freedom) acting on each node. You can see the forces and moments acting on each element and node. Landmark WELLPLAN 415 Chapter 9: Bottom Hole Assembly You can view a summary of this information in the Element Forces Table Summary of the BHA Report. This table displays the minimum and maximum magnitudes of each force and moment along with the corresponding nodes at which these forces or moments occur. You can view the minimum and maximum force and moment as well as the node at which the force or moment occurs. What are the Stresses at Each Node? The Component Stress Table from the BHA Report displays the magnitudes of each stress type (axial, bending, torsion, shear and equivalent) along with the corresponding nodes at which they occur. Stress information is reported based on stress type. 416 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly What are the Principal Stress Acting at Each Node? The principal stress table from the BHA Report displays the magnitudes of the maximum principal, minimum principal, maximum shear and equivalent stress at each node analyzed. You can determine the principal stress acting at each node. What is the Inclination and Azimuth of the Drillstring or Wellbore? The final section of the BHA Report—the Wellbore vs. Drillstring Angle Table—contains information related to the inclination and azimuth directions of each node for the string and the wellbore. You can determine the inclination and azimuth of the string and wellbore at any node. Landmark WELLPLAN 417 Chapter 9: Bottom Hole Assembly Predicting How a Bottom Hole Assembly Will Drill Ahead The drillahead analysis is useful in the planning stages, as well as during the operational stages. Drillahead analysis can be used to predict the directional behavior of a bottom hole assembly during the planning stages. Drillahead analysis makes it possible to study the effects of various components, including bent assemblies, collar sizes, stabilizer placement, hole enlargement, and component wear. During well operations, drillahead analysis can be used to adjust operating parameters to optimize performance. The drillahead analysis first performs the same analysis as in the static analysis. The program then drills ahead in 5-foot increments to predict the bottom hole assembly behavior over the user specified drillahead interval. Data is presented on the reports in increments specified by the user. The report generated for the drillahead analysis is similar to the static analysis except that information for a user specified drillahead interval is included. Defining Analysis Parameters for Drillahead Analysis Use Parameter→Analysis to input parameters needed to perform the calculations. Mark the Enable Drillahead check box in order to analyze how the assembly drills ahead. 418 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly Check Enable Drillahead to analyze how a bottom hole assembly will perform as it makes new hole. Type in data as it appears in the dialog. Analyzing Drillahead Results The reports and plots available for a drillahead analysis are the same as those available for the static analysis discusses previously. How Will the BHA Drill Ahead? Refer to the Weight on Bit Study Report section of the BHA Report (View→Report→BHA) to determine how the BHA performs over the specified drillahead interval. In this example, the BHA is very slightly building angle. Landmark WELLPLAN 419 Chapter 9: Bottom Hole Assembly Predicted survey data is appended to the existing surveys based on the drillahead parameters specified. Predicted survey data is appended to the existing surveys over the drillahead interval specified. Why is the BHA Building or Dropping? To assist you with determining why the BHA is performing as it is, you can observe the BHA Forces table on the BHA Report (View→Report→BHA). 420 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly These intermittent contact points You can determine where the are the connections touching the BHA is in contact with the wellbore. wellbore and the amount of contact force. Landmark WELLPLAN 421 Chapter 9: Bottom Hole Assembly Supporting Information and Calculations The material contained in this section is intended to provide you more detailed information and calculations pertaining to many of the steps presented during the descriptions of the analysis mode methodologies. If the information in this section does not provide you the detail you require, please refer to the section titled “References” on page 438 for additional sources of information pertaining to the topic you are interested in. Analysis Methodology Three Fundamental Requirements of Structural Analysis The Finite Element Analysis (FEA) method used in the Bottom Hole Assembly module adheres to three basic conditions of structural analysis: • First, the internal forces must balance the external forces. • Second, the solutions for each separate element must be compatible with the next element. This is necessary so that the deformed structure fits together. • Third, the laws of material behavior must be followed. Defining the Finite Element Mesh The first step completed during the analysis is to divide the drillstring into a 40 element mesh. This 40 element mesh is divided into three sections, or “zones.” The total length of the mesh, the length of each zone, and the maximum length of each element in a zone can all be set by the user to create a coarser or finer mesh. The Bottom Hole Assembly module has preset defaults for the total length of the mesh, the lengths of the individual zones, and for the elements within the zones. It is recommended that the defaults be used unless the user is very familiar with Finite Element Analysis methods. The defaults for lengths of zones 1 and 2 are 500 and 2500 feet, respectively. The length of zone 3 varies depending on the remaining length of drillstring and the remaining number of available nodes. The Aspect Ratios for zones 1, 2 and 3 default to 20, 100, and 500 respectively. The following example explains how Aspect Ratios 422 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly determine element lengths. Assume there is an 8" collar in zone 1. The maximum element length in zone 1 for an 8" collar would be: 8" X 20 (default for Aspect Ratio 1) = 160" or 13.3 ft. An exception to this is in the bottom 12 feet of zone 1 where there is a 3-foot limit for element length. The 3-foot limit is included because the drillstring closest to the bit has a significant impact on the bottom hole assembly behavior. Compute the Local Stiffness Matrix and the Global Stiffness Matrix After the drillstring has been divided into elements, each element is closely examined in terms of geometrical and physical properties. The correct representation of geometrical and physical properties— including component weight, dimensions, moment of inertia and modulus of elasticity—is very important in order to accurately represent the component for the remaining analysis. The Bottom Hole Assembly module has a catalog containing much of the information, but it is important that the user carefully selects each component to model the drillstring as closely as possible. The user should verify that all selected component properties accurately reflect the component. The local stiffness matrix [K] is an important piece of the analysis as it represents how rigid or bendable a component is. The relationship between the stiffness matrix [K], and the nodal forces, displacements, rotations, and moments is defined in Equation 1. (Equation 1) {F} = [K] {δ} where: {F} = vector of nodal loads, and moments [K] = stiffness matrix {δ} = vector of nodal displacements, and rotations The stiffness matrix [K] is composed of the following: E = Young’s Modulus (lb/in2) I = Moment of Inertia (in4) Landmark WELLPLAN 423 Chapter 9: Bottom Hole Assembly L = Length between nodes (in) G = Modulus of Rigidity = E/2 (1+v) J = Polar Moment of Inertia = 2I v = Poisson’s Ratio Young’s Modulus (E) varies with material type. Young’s Moduli for a few common materials are listed below. Material Young’s Modulus Steel 29 X 106 psi Aluminum 10.3 X 106 psi Monel 26 X 106 psi Tungsten 87 X 106 psi Beryllium-copper alloy 19.5 X 106 psi The Moment of Inertia (I) varies based on the cross-section of the element in question. The Moment of Inertia for a tubular element is given in Equation 2. (Equation 2) I= π/64 (OD4 - ID4) where: OD = Outside diameter (in) ID = Inside diameter (in) Equations 1 (page 423) and 2 (above) clearly present the importance of accurately representing the bottom hole assembly components. An incorrect material type or tubular dimension can make a significant difference. Figure 1 (on the following page) is the expanded form of Equation 1 (above), and contains more complete descriptions of the vectors and matrix. The forces and moments acting on the single element in Figure 4 (page 428) are calculated using the matrix algebra illustrated in Figure 1 (page 425). The data in this matrix is for the element between node “n” and node “n+1.” Note that each element is defined by two nodes. There are similar matrices for the element between node “n+1” and node “n+2.” 424 WELLPLAN Landmark Landmark Figure 1: Expanded Stiffness Matrix Equation Fx(n) (12EI)/L3 (6EI)/L2 (-12EI)/L3 (6EI)/L2 X(n) Fy(n) (12EI)/L3 (-6EI)/2 (-12EI)/L2 (-6EI)/L2 Y(n) Fz(n) AE/L -AE/L Z(n) WELLPLAN Mx(n) (-6EI)/L2 4EI/L (6EI)/L2 (2EI)/L θx(n) My(n) = (6EI)/L2 4EI/L (-6EI)/L2 (2EI)/L X θy(n) Mz(n) GJ/L GJ/L θz(n) Fx(n+1) (-12EI)/L3 (-6EI)/L2 (12EI)/L3 (-6EI)/L2 X(n+1) Fy(n+1) (-12EI)/L2 (6EI)/L2 (12EI)/L3 (6EI)/L2 Y(n+1) Fz(n+1) -AE/L AE/L Z(n+1) Chapter 9: Bottom Hole Assembly Mx(n+1) (-6EI)/L2 2EI/L (6EI)/L2 4EI/L θx(n+1) My(n+1) (6EI)/L2 2EI/L (-6EI)/L2 4EI/L θy(n+1) Mz(n+1) GJ/L GJ/L θz(n+1) 425 Chapter 9: Bottom Hole Assembly The individual matrices for all the element are combined to form one matrix for the entire bottom hole assembly. The expanded matrix [K] containing data for all 40 nodes included in the analysis is structured as in the Figure 2 (below). Figure 2: Matrix Structure Stiffness matrix [K] for element between nodes 1 and 2 Nodes 2 and 3 Nodes 3 and 4 Nodes 37 and 38 Nodes 38 and 39 Nodes 39 and 40 426 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly Figure 3: Simplified Beam Element Length L Y(n) Y(n+1) Deflected Position Figure 3 (above) is a simplified beam element to illustrate the angle θ as it is used in Figure 4 (page 428). The angle θ is used to measure the deflection of the element from the reference axis. The individual element stiffness matrices are computed and combined to form the global stiffness matrix. This is a necessary step towards ensuring a complete solution for the entire bottom hole assembly, rather than a number of individual solutions for several elements. The global matrix is a necessary step towards satisfying the fundamental requirements of structural analysis mentioned earlier. Landmark WELLPLAN 427 Chapter 9: Bottom Hole Assembly Degrees of Freedom Figure 4: Single Beam Element X Fx(n+1) M x(n+1) Z Fz(n+1) M z(n+1) Fx(n) M z(n) Fy(n+1) Fz(n) M y(n+1) Node n + 1 Mz(n) Fy(n) M y(n) Node n Y Refer to Figure 4 (above) for an illustration of a single beam element. This particular illustration shows one element with six degrees of freedom (DOF). A DOF is an unknown displacement that can occur at a point, or node. As shown in Figure 4, each node can move along the X, Y and Z axes, constituting three DOF—one DOF along each axis. In addition, there can also be a rotation around each axis. This is an additional three DOF, for a total of six at each node. Notice the forces and moments acting on the beam at each node. During the mesh generation step, the entire bottom hole assembly is divided into 39 similar single beam elements and analyzed. Boundary Conditions Boundary conditions are the physical constraints acting on the bottom hole assembly. Boundary conditions are important to the analysis to set how the structure is supported and constrained. Boundary conditions 428 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly make it possible to solve the finite element analysis. The Bottom Hole Assembly module provides six default boundary conditions that can be selected for the top and bottom nodes. The Bottom Hole Assembly module’s system defaults do not apply boundary conditions to nodes between the top and bottom nodes. An experienced user familiar with FEA (and with assistance from Landmark) can define additional boundary conditions and can enforce boundary conditions at additional nodes. It is recommended that the defaults be used unless the user is familiar with finite element analysis methods. The following list defines the seven default boundary conditions selections available for the top and bottom nodes. l Full pin: All three translations are specified and rotations are free. l Full Fix: All three translations and rotations are specified. l Pin with Axial Slider: Two lateral translations (X, Y) are specified. Z translation is free, and all three rotations are specified. l Fix with Axial Slider: Two lateral translation (X, Y) are specified. Z translation is free, and all three rotations are specified. l Fix Axial: Two lateral translations (X, Y) are free. Z is specified, and X,Y, and Z rotations are free. Landmark WELLPLAN 429 Chapter 9: Bottom Hole Assembly l Fix Torsion: All three translations (X, Y, Z) are free, two rotations (X, Y) are free, and Z rotation is specified. l Fix Rotations: All three translations are free (X, Y, Z) and two lateral rotations (X, Y) are specified, and Z rotation is specified. Displacements Rotations Description X Y Z X Y Z Full Pin Set Set Set Free Free Free Full Fix Set Set Set Set Set Set Pin with Axial Slider Set Set Free Free Free Free Fix with Axial Slider Set Set Free Set Set Set Fix Axial Free Free Set Free Free Free Fix Torsion Free Free Free Free Free Set Fix Rotation Free Free Free Set Set Free 430 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly For each of the seven previous types, it is possible to modify the radius, angle, axial displacement, and twist for each type. l Radius: Determines the string position from the center of the wellbore. A large value places it against the wellbore. l Angle: Locates the string relative to the high side of the hole. A radius of 1.0 unit and an angle of 90 degrees places the string one unit (inch, mm, or so forth) to the right of the center of the hole. l Axial Displacement: Used to initially displace the string. l Twist: The rotation from the high side of the hole. This is used to impart an initial twist to the string. Constructing the Wellbore and Bottom Hole Assembly Reference Axis Survey data and wellbore diameters are important pieces of information supplied by the user. The Bottom Hole Assembly module uses this information to construct the wellbore. Each survey data point supplied by the user is used to calculate location reference coordinates for each survey point of the wellbore using the survey calculation method supplied by the user (that is, Radius of Curvature and so forth). Next, the coordinates of the bottom hole assembly nodes are determined as if the bottom hole assembly is lying along the centerline of the wellbore, with the bit at the depth specified by the user. A bottom hole assembly reference axis (Z) is established by using the inclination and direction as interpolated at the bit location. The Z reference axis is tangent to the wellbore and points toward the surface. Landmark WELLPLAN 431 Chapter 9: Bottom Hole Assembly The X and Y reference axes are also established. The X axis points toward the surface (vertical) and theY-axis is parallel to the surface (lateral). Hole diameters are assumed to be constant over the interval specified by the user in the WELLPLAN Wellbore Editor. Calculating the Solution Using the information from the previous steps of the analysis, the force/contact solution can be calculated. This is a complex, iterative procedure. First, the drillstring finite element model is laid out along the z-axis described above. Unless the wellbore is straight, the drillstring finite element model penetrates the wellbore described by the surveys. At this point, the program begins to determine the force acting between the wellbore and the drillstring. The boundary conditions are enforced on the nodes specified. All other nodes have no boundary conditions applied. The program determines where the drillstring has (theoretically) penetrated the wellbore and calculates the restoring force necessary to move the node back into the wellbore. If the node is already inside the wellbore, no force or displacements are applied to the node. These steps are repeated until the changes in displacements at all nodes fall below a set tolerance. The objective is to determine the forces necessary to move the nodes along the reference axis to the corresponding nodal position lying along the wellbore centerline. When this is accomplished, the solution is considered complete. At this point, the axial forces, torque, stresses and coordinates (X, Y, and Z) of each node are known. Bit Tilt and Resultant Side Force The following two figures are inclination and directional views of the forces acting on a bit. In these figures, the following nomenclature is used. 432 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly Figure 5: Inclination Forces FI FR FA φΑ φI φR TAN Landmark WELLPLAN 433 Chapter 9: Bottom Hole Assembly Figure 6: Direction Forces N TAN θD FR FA θA θR FD FI = Inclination Force FD = Direction Force FRI = Resultant Inclination Force FR = Resultant Direction Force φI = Wellbore Inclination fA = Bit Inclination fR = Resultant Force Inclination Angle θD = Wellbore Direction Angle θA = Bit Direction Angle θR = Resultant Force Direction Angle These figures can be somewhat misleading because the inclinational (FI) and directional (FD) side forces compared to the axial force (FA) in the diagrams are represented approximately equal in magnitude. In normal operating conditions, the axial force (FA) is usually 10 to 100 times the magnitude of the side forces. 434 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly The bit tilt is defined as the angle between the centerline of the wellbore and the centerline of the bit. As shown, there is a bit tilt in both the inclination and azimuth directions. Bit tilt is a result of the bending characteristics of the bottom hole assembly and the resulting force acting on the bit. The resultant force is a vector solution of all the forces acting on an individual node, and it is this force that determines the magnitude of the displacement from the center line. The bit trajectory is determined by the resultant force acting on the bit and by the bit tilt. Drillahead Solutions The Bottom Hole Assembly module is capable of two analysis modes: l The static or “in-place” solution has been explained in the previous discussion. A static solution assumes the bit is stationary at the user specified depth. l The “drillahead” solution advances the bit depth, in 5 foot intervals, through the interval specified by the user. At each of the 5 foot intervals, a static solution is performed. The drillahead solution assumes: • The bit will drill in the direction it is pointed. • The bit will cut sideways due to the presence of side forces generated in the inclination and direction axes. • The formation has isotropic rock properties. Although side cutting is affected by penetration rate, it is not entirely a function of the same parameters that affect penetration rate. Lateral penetration rates do not always vary with penetration rate. One reason for this can be attributed to the variety of bits available. Different bits have different side cutting abilities. To calculate the lateral penetration rate, the Bottom Hole Assembly module uses the Warren Penetration Rate Model. Landmark WELLPLAN 435 Chapter 9: Bottom Hole Assembly Warren Penetration Rate Model (Equation 3) CS Ri = A (S2)(D3) C + (RSB)(Fi2) (RS) (D) Where: Ri = Lateral penetration rate (ft/hr) CS = Side cutting coefficient = bit coefficient /10.0 S = Rock strength = formation hardness / 10.0 D = Bit diameter (in) Rs = Rotary speed (rpm) Fi = Lateral side force at the bit (kips) A = Bit constant = 0.03 B = Bit constant = 0.60 C = Bit constant = 2.80 Bit Coefficient Bit coefficients indicate how efficient a bit will cut sideways. Values for bit coefficient range from 1 - 100. Note that a value of 0 indicates the bit does not cut sideways, and the wellbore trajectory will be based solely on bit tilt. The following table includes suggested bit coefficients for roller cone bits. Typically range for this type of bit is 20 - 80, with 20 used for soft formations, and 80 used for hard formations. IADC Series Bit Coefficient 8 20-30 3,7 30-40 2,6 40-60 1,4,5 60-80 436 WELLPLAN Landmark Chapter 9: Bottom Hole Assembly The values for fixed cutter bit coefficients are more difficult to determine from the IADC classification system. Cutter size, density, and placement impact the determination of bit coefficient. Fixed Cutter Bits Bit Coefficient Flat Faced Diamond 0-5 Step Profile/Small Cutters 10-20 Bladed/Small Cutters 20-40 Step Profile/Large Cutters 40-60 Bladed/Large Cutters 60-80 Formation Hardness Formation hardness is used in Equation 3 (page 436) to model the formations resistance to the bit side cutting capability. Formation hardness is a number between 0 and 60, with the larger numbers indicating the relative hardness of the formation. The table below correlates formation hardness to rate of penetration and formation description. Formation Formation ROP ROP Description Hardness (ft/hr) (m/hr) Soft 10 100+ 30+ Medium Soft 20 75 23 (Shallow Gulf Coast) Medium 30 50 15 (Above 10,000 feet) Medium Hard 40 30 9 (Below 10,000 feet) Hard 50 20 6 (Granite) Rigid 60 10 3 (Igneous Rock) Landmark WELLPLAN 437 Chapter 9: Bottom Hole Assembly References Millheim, K.K., Jordan, S., and Ritter, C.J., “Bottom Hole Assembly Analysis Using the Finite Element Method,” Journal of Petroleum Technology, February, 1978, 265-74. Warren, T.M., “Factors Affecting Torque for a Roller Cone Bit,” Journal of Petroleum Technology, September 1984, 1500-08. Rockey, K.C., Evans, H.R., Griffiths, D.W., and Nethercot, D.A., “The Finite Element Method,” Granada Publishing Limited, 1975. Williams, J.B., Apostal, M.C., Haduch, G.A., “An Analysis of Predicted Wellbore Trajectory Using a Three-dimensional Model of a Bottomhole Assembly with Bent Sub, Bent Housing, and Eccentric Contact Capabilities,” SPE 19545, 1989. Millheim, K., Jordan, S., Ritter, C.J., “Bottom Hole Assembly Analysis Using the Finite Element Method,” SPE 6057, 1978. Millheim, K., “Directional Drilling” (an 8 part series), Oil and Gas Journal, 1979. 438 WELLPLAN Landmark Chapter 10 Notebook Notebook provides a wide range of simple operational calculations. The calculations in Notebook are divided into three categories, including: Miscellaneous, Fluids, and Hydraulics Overview In this section of the course, you will become familiar with all aspects of using the Notebook module. To reinforce what you learn in the class lecture, you will have the opportunity to complete several exercises designed to prepare you for using the program outside of class. The information presented in this chapter can be used as a study guide during the course, and can also be used as a reference for future torque and drag analysis. Starting Notebook You must have a Case open to use the Notebook module even though case data will not be used in any analysis within the Notebook module. Open the Case ‘9 5/8” Casing’ in the Project ‘Guided Tour’, and Well ‘Tour #1’. There are two ways to launch the Notebook module. You can select Notebook from the Modules Menu, or you can click the Notebook Button on the Modules Toolbar. Landmark WELLPLAN 439 Chapter 10: Notebook Choose Notebook from Modules Menu, or by clicking the Notebook button Select desired analysis mode from submenu or from Mode drop down list Notebook Analysis Modes Notebook offers three analysis modes. The analysis mode are essentially a grouping of similar operational calculations. The analysis modes or groups are: l Miscellaneous - This group of calculations include: determining the linear weight (in air and buoyed) of a component or a section of pipe, calculating the block line cut off length and analyzing leak off test data. l Fluids - This group of calculations can be used to achieve the desired fluid weight by mixing fluids, diluting, or weight up. You can also determine the compressibility of a water or oil based mud. l Hydraulics - This group of calculations can be used to determine the pump output, annular and pipe volumes, nozzle TFA or sizes, and buoyancy factors. 440 WELLPLAN Landmark Chapter 10: Notebook Miscellaneous Mode To access the Miscellaneous mode, select Miscellaneous from the Mode drop down list. The Miscellaneous mode calculates: l Linear Weight l Blockline Cut Off Length l Leak Off Test Linear Weight Use the Parameter→Linear Weight dialog to quickly calculate the weight-in-air and buoyed-weight of a component based on a specified OD, ID, and mud weight. To calculate the linear weight, specify the components ID and OD, its length, the density of the mud, and whether it is a steel or aluminum component. Enter required input data Click in output Specify component section to material calculate and view results Blockline Cut Off Length Use the Parameter→Blockline Cut Off dialog to quickly calculate the recommended cut-off length for rotary drilling lines. These calculation values are based on API RP 9B. Landmark WELLPLAN 441 Chapter 10: Notebook Click a radio button to Select a Drum Diameter select Drum Type from the list of drum diameters suitable for the respective mast Select a Mast Height height. from the list View results Leak Off Test Use the Parameter→Leak Off Test dialog to quickly calculate the formation breakdown pressure and equivalent mud gradient from a leak off test (LOT). The air gap and sea depth can be set to zero for a land rig. Click a field in the Output group box to display results 442 WELLPLAN Landmark Chapter 10: Notebook Fluids Mode To access the Fluids analysis mode, select Fluids from the Mode drop down list. The Fluids Mode calculates: l Mix Fluids l Dilute / Weight Up l Fluid Compressibility Mix Fluids Use the Parameter→Mix Fluids dialog to quickly calculate the density and volume of a fluid when two fluids with different densities and volumes are mixed. Specify initial volume and density of one fluid Specify the density and volume of the second fluid Click in output to view results Dilute /Weight Up Use the Parameter→Dilute/Weight Up dialog to calculate the resulting volume when the density of a fluid is increased or decreased to a different density. You can opt to keep the volume constant. In this case, the required dump volume is determined. Landmark WELLPLAN 443 Chapter 10: Notebook To calculate a volume, specify the volume and density of the initial fluid, the density of the final fluid mixture, and the density of the heavier fluid you want added. If you mark the Maintain total volume check box, the total volume of the final mixture will not be allowed to exceed the volume specified in the Initial Volume field. You must specify volumes in all fields in order for a resulting volume to be calculated. Enter the volume and density of your original fluid Required Enter the required fluid density operation achieve required Specify the density of the fluid density will be you are using to dilute or weight indicated up the original fluid with Check box to keep volume constant. In this box is checked, the Initial Dump Volume will be calculated Fluid Compressibility Use the Parameter→Fluid Compressibility dialog to quickly calculate the volume of mud that must be pumped to overcome the compressibility of the fluid. Specify the hole volume and test pressure Specify the mud type Click in output section to view results 444 WELLPLAN Landmark Chapter 10: Notebook Hydraulics Mode To access the Hydraulics Mode, select Hydraulics from the Mode drop down list. The Hydraulics mode calculates: l Pump Output l Annular capacity, volume and velocity l Pipe capacity, volume and velocity l Nozzle TFA or sizes based on TFA l Buoyancy factors Pump Output Use the Parameter→Pump Output dialog to quickly calculate the flow rate and volume-per-stroke for a user-defined pump configuration. Enter all required input data Rod diameter is not required for a triplex pump Click radio button to select pump type Click in output section to view results Annular Use the Parameter→Annular dialog to calculate the capacity, volume, and velocity for two annular sections. Landmark WELLPLAN 445 Chapter 10: Notebook Enter flow rate Total annular volume Enter data for first annular section Calculated data for sections Enter data for Calculated second annular fluid velocity section in annulus Pipe Use the Parameter→Pipe dialog to calculate the linear capacity, volume, linear displacement, total displacement and velocity for two pipe sections. Enter flow rate Total pipe capacity Total fluid displacement Enter data for one pipe section Calculated results for each section Enter data for second pipe section Nozzles Use the Parameter→Nozzles dialog to calculate the nozzle sizes required to produce a desired total flow area (TFA) or to calculate the TFA based on a specified number and sizes of nozzles. 446 WELLPLAN Landmark Chapter 10: Notebook Input size and number Click the Total of nozzles to calculate Flow Area radio TFA button to calculate TFA based on specified nozzle sizes Input TFA to calculate size and number of nozzles Click the Nozzles radio button to calculate nozzle sizes base on specified TFA. Buoyancy Use the Parameter→Buoyancy dialog to quickly calculate the buoyancy factor based on the specified mud density. Specify mud weight Click in output section to calculate the buoyancy factor Landmark WELLPLAN 447 Chapter 10: Notebook Calculations Block Line Cut Off Length Π Length = Laps × Drum Diameter × 12 Dilute/Wt Up Fluid V1 D1 +V 2D 2 = V 3 D 3 Where: V1 = Volume of one material to be mixed D1 = Density of V1 material V2 = Volume of second material to be mixed D2 = Density of V 2 material V3 = Total volume D3 = Density of total volume Fluid Buoyancy Mud Weight Buoyancy = 1 − Steel Density 448 WELLPLAN Landmark Chapter 10: Notebook Fluid Compressibility Test Pressure [ psi ] × Hole Volume [bbl ] Vol to Pump [bbl ] = Constant where: Constant for oil-based mud = 2.2e5 Constant for water-based mud = 3.16e5 Leak Off Test Formation Breakdown Pressure = TVD × 0.052 × Mud Density + Test Pressure Density Formation Breakdown Pressure Equivalent Mud Gradient = TVD Formation Breakdown Gradient = Formation Brekdown Pressure − Sea Depth × Seawater Gradient TVD − AirGap − Sea Depth Mix Fluids V1 D1 +V 2D 2 = V 3 D 3 Where: V1 = Volume of one material to be mixed D1 = Density of V1 material V2 = Volume of second material to be mixed D2 = Density of V 2 material V3 = Total volume D3 = Density of total volume Landmark WELLPLAN 449 Chapter 10: Notebook Pump Output For a duplex pum p Q = 1 . 568 e −6 × L ( 2 × d r − d y ) × N × η 2 2 W here: L = stroke length dλ = liner diam eter dr = rod diam eter N = stroke rate η = volum etric efficiency For a triplex pum p: Q = 2 . 3555 e − 6 × L × d λ × N × η 2 Nozzle Area 2 Π d n TFA = ∑ ni × ( i ) i =1 4 32 Where: di = Size of the nozzle ni = Number of nozzles in each group i = Number of groups 450 WELLPLAN Landmark
Copyright © 2024 DOKUMEN.SITE Inc.