SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER INDEX BULLETIN ITEMCHAPTER 13 Page 1 of 24 PAGE 13.1 INTRODUCTION ............................................................................................................. 2 13.2 LOST CIRCULATION ..................................................................................................... 2 13.2.1 CAUSES OF LOST CIRCULATION ....................................................................... 2 13.2.2 CLASSIFICATION OF LOSSES.............................................................................. 2 13.2.3 DETECTION OF LOST CIRCULATION ZONES .................................................. 2 13.2.4. PREVENTATIVE MEASURES ............................................................................... 3 13.2.5 CURATIVE MEASURES ......................................................................................... 3 13.2.6 LOST CIRCULATION PILLS.................................................................................. 5 13.2.7 SPECIAL DRILLING TECHNIQUES FOR LOSS ZONES.................................... 5 13.3 DRILLING UNSTABLE FORMATION .......................................................................... 6 13.3.1 CLAY DISPERSION................................................................................................. 6 13.3.2 SWELLING SHALES ............................................................................................... 6 13.3.3 CAVING SHALES.................................................................................................... 7 13.3.4 UNCONSOLIDATED SANDS................................................................................. 8 13.4 REAMING......................................................................................................................... 8 13.5 HOLE CLEANING ........................................................................................................... 9 13.5.1 WHEN IS HOLE CLEANING REQUIRED?........................................................... 9 13.5.2 RECOMMENDED HOLE CLEANING PARAMETERS (FOR HIGH ANGLE WELLS) 10 13.5.3 HOLE CLEANING CYCLES ................................................................................. 10 13.5.4 PUMPING SWEEPS ............................................................................................... 10 13.5.5 GENERAL RULES OF THUMB............................................................................ 11 13.5.6 HOLE CLEANING BEST PRACTICES IN HIGH ANGLE WELLS ................... 12 13.6 STUCK PIPE ................................................................................................................... 12 13.6.1 STUCK PIPE MECHANISMS................................................................................ 13 13.6.2 PREVENTION OF STUCK PIPE ........................................................................... 13 13.6.3 DETECTION OF STUCK POINT .......................................................................... 15 13.6.4 FREEING STUCK PIPE ......................................................................................... 15 13.6.5 BACK-OFF PROCEDURE ..................................................................................... 16 13.6.6 REPORTING ........................................................................................................... 17 13.7 FISHING AND JARRING OPERATIONS .................................................................... 17 13.7.1 GENERAL PRACTICES ........................................................................................ 17 13.7.2 USE OF FISHING TOOLS ..................................................................................... 18 13.7.3 FISHING FOR CST (SIDEWALL SAMPLE) BULLETS ..................................... 21 13.7.4 ALLOWABLE PULL ON DRILL PIPE................................................................. 21 13.8 PLUGGING BACK AND SIDETRACKING OPERATIONS....................................... 22 13.8.1 GENERAL............................................................................................................... 22 13.8.2 SETTING A BALANCED CEMENT PLUG ......................................................... 22 13.8.3 SIDETRACKING .................................................................................................... 23 EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 2 of 24 13.1 INTRODUCTION Hole problems and fishing cover numerous operations, many of which are handled on a daily basis on the rig site. This chapter highlights those areas, which may lead to the loss of the hole unless remedial or corrective action is taken. Reference should also be made to chapter 11, "The ABC of Stuck Pipe" (EP91 - 1908), the Drilling Fluids Manual, the Drilling Engineers Notebook and Training to Reduce Unscheduled Events (TRUE) manual. Several publications have been made on Borehole stability and hole cleaning. 13.2 LOST CIRCULATION Reference should be made to chapter 11 and the Drilling Fluids Manual (EP88-2637). Although mud losses of about 1 bbl/ft occur during drilling of loose sands in surface holes, severe mud losses and lost circulation do not normally occur in the Niger Delta area. Lost circulation zones have however been encountered on the periphery of the Delta and returns have been lost occasionally when mud weights had to be increased sharply after drilling into geopressured zones. 13.2.1 CAUSES OF LOST CIRCULATION Losses may occur in highly porous and permeable formations. The severity depends on the mud weight, Equivalent Circulating Density (ECD) and pressure surges that may be created. Lack of care while performing leak off/limit tests and excessive Rate Of Penetration (ROP) while drilling surface hole can also result in heavy mud losses, as can the improper handling of kicks and drilling into depleted reservoirs with too high an overbalance. For proper analysis, it is important to have as much information available as possible from the time losses were detected (e.g. ROP, mud properties, mud weights in/out, solid content, sand percent, stand pipe pressure, etc.). 13.2.2 CLASSIFICATION OF LOSSES 1. Trip losses. 2. Minor or seepage losses (less than 20 bbls/hr). 3. Moderate to severe losses (20 - 100 bbls/hr). 4. Total loss of circulation 13.2.3 DETECTION OF LOST CIRCULATION ZONES The point of initial loss in naturally occurring loss zones is normally at the bottom of the hole. Induced fractures however, may occur anywhere in the open hole interval, but are frequently found immediately below the last casing shoe. If severe losses occur while tripping, circulating or increasing mud weights, the loss zone can be at any depth. To be able to locate the loss zone, it may be necessary to run wireline logs such as a spinner survey, a temperature survey, or a radioactive tracer survey. Detection of mud losses during drilling is observed by a change in tank level and reduction in mud returns. This may be accompanied by either a sudden increase in pump pressure indicating bridging in the hole, or by a decrease in pump pressure indicating a reduction in annulus level. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT then the loss circulation has to be cured first before the kicking formation can be controlled. Setting a barytes plug is the last resort before running out of mud materials. If a well kicks as a result of losses. This is to prevent impairing the formation. Barytes plug formulation is given in SIPM EP 89 1500. it should be noted that reducing the pump rate might actually increase the ECD if the resultant hole cleaning is ineffective. If losses are as a result of fractures and are not severe. Monitor the total bottom hole circulating pressure. When loss circulation is expected or when normal circulation has been restored after losses: 1. Trip losses and pressure surges must be reduced by improved mud conditioning and controlled pipe handling/avoidance of excessive pipe speed respectively. If losses occur while drilling the drain hole (objective sand) use of acid soluble "lost circulation material" like Calcium Carbonate should be considered first. Treating the mud in circulation with Loss Circulation Material (LCM) e.2. Spotting concentrated LCM plugs across the zone may cure severe or total losses. reducing the viscosity of the mud. However. it may be necessary to set a casing to seal off the loss zones.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 3 of 24 Severe and moderate losses may be encountered in depleted zones or in cavernous formations. PREVENTATIVE MEASURES Keep the mud properties within the limits set out in the drilling programme. e.g. The cause of the losses must be determined in order to treat it effectively. This is achieved by reducing the mud weight. Keep mud weights as low as safely possible. 13. 3. without any safety margin on the mud weight. LCM material should be added (nozzles sizes permitting) to the kill mud. 2.g. This is achieved by keeping the hole full at all times. and reducing the cuttings load by controlling the penetration rate and possibly by reducing the pump rate. If none of the various LCM pills and EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT .2. This can be done with LCM pills pumped down either the drill pipe or annulus. Avoid excessive pipe running speed to prevent pressure surges and in the areas where losses are severe. 5 or 10 sacks/hour of Mica Fine and Walnut Fine added at the hopper can sometimes cure partial losses. Run pipe slowly to avoid pressure surges. 13.4. If losses occur while handling a kick. 4. This is equal to the sum of the hydrostatic head due to the mud column plus the pressure drop in the annulus. Care must be taken to displace this plug below the bit so as to avoid the bit being plugged. Solids content should be controlled within the stated limits and surface hole drilling at a controlled rate of penetration to avoid over loading the annulus. the viscosity and gel strength should be kept as low as possible. In particular.5 CURATIVE MEASURES The most important step when losses are experienced is to maintain control of the well. carbonates. Keep the other mud properties within the limits set out in the drilling programme. it is sometimes sufficient to reduce the total bottom hole circulating pressure. in a 20 bbl pill. When this condition prevails the procedure set out below should be followed: 1. When the well is static. the setting of casing as soon as a nonpermeable zone is encountered. a) Curing Minor or Seepage Losses (less than 20 bbls/hr): Small continuous mud losses when drilling permeable low pressure reservoirs may occur.100 bbls of LCM pill above the loss zone and pull back into the shoe. Pump diesel oil spacer down the hole with the bit just above the lost zone. In cases of severe losses. Clean the cement pump and lines with diesel to remove all traces of water to prevent flash setting. but this must be discussed in detail with the office. Do not forget to remove the suction strainers and clean out the pump after it has been used for pumping LCM pill. After experiencing lost circulation problems.). such as gunk. 2. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . nutplug fine. acid soluble pill should be the first option to consider. Keep annulus filled up with water and record the amount of water consumed. 300 lbs/bbl bentonite mixed in diesel is then pumped down. Add the plugging materials slowly and continuously to mud (e. but still maintaining at least 150 psi over-balance./bbl of mica fine. drill ahead carefully. calculate the new weight required.g. a gunk squeeze can be tried. c) Curing Total Loss of Circulation With total losses. 3. should be seriously considered. are successful. if water rather than mud come into contact with the open hole. Note: Never pull out of hole when circulation is lost and mud level in annulus cannot be seen. + 5 lbs. Follow this gunk mixture with diesel spacer. drilling without returns may be considered. 4. Slow down pump so long as good hole cleaning is maintained and reciprocate string slowly.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 4 of 24 soft plugs. sodium silicate solution etc. Wait for a minimum of one hour then run back to the top of the LCM plug and circulate to the new mud weight. When returns are established and the minimum over-balance is still achievable. Note: Whenever possible. 2. After circulating and conditioning. etc. If possible. the mud weight can be reduced in stages to the minimum weight permissible. b) Curing Moderate to Severe Losses (greater than 20 bbls/hr) Spot 50 . there is a danger of stuck pipe due to destabilisation of the formation. wash back to bottom and circulate LCM pill out. This method utilises the swelling property of bentonite in the presence of water: 1. 13. The mud cap balances the formation pressure. It is this solid that plugs off lost circulation zones. when it comes in contact with Calcium Chloride solution. it forms a highly viscous. add the following to above: Calcium Carbonate (Coarse) 5 lbs/bbl Note: . Soda Ash should not be used because the viscosity of slurries made from HEC and Soda Ash drops rapidly. In bad cases of losses. Because of EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . these products should be tried whilst keeping in mind their high price. Sufficient mud is kept in the annulus to hold any formation pressure. A general formulation will be as follows: a) For minor or seepage losses: CHEMICALS Brine Base Fluid Caustic Soda to provide pH of 10 HEC (viscosifier) 2 lbs/bbl Starch (Fluid Loss) 2 lbs/bbl Calcium Carbonate (fine) 20 lbs/bbl b) For a moderate to severe losses. Sodium silicate solution is a clear liquid which. 13. lost circulation cannot be cured and some special techniques are used for drilling the lost zones. CHAPTER 13 Page 5 of 24 6. add the following to above: Calcium Carbonate (medium) 10 lbs/bbl c) For very serious losses.7 SPECIAL DRILLING TECHNIQUES FOR LOSS ZONES In some cases. as soon as it comes into contact with water. Whilst the bentonite is pumpable when mixed in diesel.2.6 LOST CIRCULATION PILLS It should be noted that treatment depends on severity but the idea is to have distribution of particles as wide as possible in order to close the various pores sizes in the loss zone.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING 5. Water is pumped down the drill pipe and mud down the annulus simultaneously. Drilling with air. forms a white precipitate of Calcium Silicate. putty like material which can plug off the formation. A good pH is necessary for HEC to yield properly.2. Displace gunk mixture out of the bit with mud.The concentrations of the various grades of Calcium carbonate can be increased to achieve desired results. Blind or floating mud cap drilling can also be carefully considered. gas or aerated mud can be used but have a limited application. Successes have been claimed for the sized cellulose products such as "Liquid Casing".300 psi. Pump simultaneously down drill pipe and annulus and apply a squeeze pressure of 100 . A cement squeeze with the slurry containing loss circulation material can be considered if all other methods fail. SPDC recommends whole mud dilution. 2. blind or floating mud cap drilling should be limited to short intervals. Inhibition with salts such as KCL and encapsulation with polymers will also reduce dispersion. Maintaining fully inhibited mud might reduce the hole problems. Caving Shales 4. On advice from the office.3. drilled solids become dispersed in the mud. High concentrations of hydroxyl ions in the drilling fluid may also increase the rate of clay dispersion. 13.3 DRILLING UNSTABLE FORMATION The following phenomena frequently give rise to drilling. They cause tight hole and sometimes bit balling. Unconsolidated sands. and mud control problems (refer to chapter 6 for more information): 1. Dispersion of clay and other drilled solids. Swelling clay 3. viscosity and gel strengths. The main cause of clay dispersion is the nature of the formation being drilled and the type of mud in use. Nevertheless. Mud density and solids content can be controlled by the efficient use of well-maintained solids control equipment. Treatment: Maintain the pH below 9. Treatment: If this Shale is known to be present.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 6 of 24 the absence of cuttings removal.5 if possible.3. the mud will have to be continuously diluted and treated to maintain constant mud properties. Use non-dispersed polymer mud without lignosulphonate dispersant. completion.2 SWELLING SHALES Some Shale undergoes plastic deformation when drilled and squeezed into the borehole. 13. the mud weight must be increased prior to drilling into the formation to prevent the start of movement. a proprietary additive. causing an increase in mud density. A deviated hole requires increased wellbore support from the mud and hence the density will need to be higher than that for a vertical hole at same depth. 13. which may result in a stuck string or frequent reaming.1 CLAY DISPERSION When clays or Shells are drilled with water-based mud. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . as will the use of dispersants such as Lignosulphonate. such as a lubricant may be added. SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING Note: . Of most importance is to immediately increase the mud gradient to an adequate level to stop or at least minimise the amount of cavings. Pieces of shale (caving) are often seen in large quantities on the shale shaker once a failure has occurred.3. with their high slip EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . It should be noted that a build up of these cavings and cuttings resulting from washouts could lead to hole pack-off around the BHA. The following factors play important roles in keeping the hole clean: 1.In addition. Maximum circulation rates In addition.mud pressure penetration can be greatly reduced by use of Sodium Silicate or eliminated with POBM/LTOBM . Mud viscosity with YP ranging between 40 to 50 lb/100ft2 2. any reduction in open hole time will reduce problems as all water based mud. It is always advisable to increase the mud gradient prior to entering known weak shale. 13.That the first 8000 ft in the Niger Delta has very fresh formation water. CHAPTER 13 Page 7 of 24 . the possibility of particular shale to "cave-in" depends on mud pressure penetration and its chemical potential (often called osmosis). Good hole cleaning is critical to minimise the risk of stuck pipe in caving boreholes. Therefore. Slow incremental increases in mud gradient are not advised since significant failure of the borehole will occur if the mud gradient is too low.Minimise nozzle velocity when drilling unstable formations by using larger nozzles. . The rheology should be adequate to clean the large diameter cavings. The addition of Sodium Silicate will assist with the mud pressure penetration problem.3 CAVING SHALES Shales fail when the borehole stress on them exceeds their strength as a consequence of drilling through.Borehole stability Template. . any swellable clay is already in a "swollen" state. Waiting for cavings to appear over the shale shakers before increasing the mud gradient should only be done when shale encountering was not anticipated. Moreover. Treatment: Design practice to cub shale failure due to stress of drilling . Pipe rotation 3. will eventually water wet and de-stabilise hydratable formations. however inhibiting. (it is desirable to run bits without nozzles when wiper tripping to ensure high annular velocities).KCl is a very effective swelling inhibitor and will deal with this issue as well as possible for WBMs. a rule of thumb is to keep it less than 300 ft/sec. 2 x DC. from surface to + 8000 ft. When drilling productive unconsolidated sands.g. as percolated gas may have accumulated below the bridge. 6. 4.4 UNCONSOLIDATED SANDS Enlargement in unconsolidated sands is a common phenomenon in the Niger Delta. a conventional rock bit with extra gauge protection should be run without nozzles and the normal drilling circulation rate used. use the following guidelines: 1. 2 x DCs. without rotating. resulting in a hydraulic piston which can break down the formation. Stab. formation testing and completion. out of the hole.: Bit. do not use a stiff assembly. When reaming is necessary. When reaming a mud motor section.4 REAMING Whenever an under-gauged bit is pulled out. Ensure the hole is effectively cleaned and the solids control equipment is operating efficiently. Whenever a mud motor is run for kicking off or course correction purposes.70% of the previous pumping rate used for drilling. CHAPTER 13 Page 8 of 24 13. Extreme care should be taken when reaming bridges. 5. the mud motor drilled section must be reamed and "smoothed out" before drilling ahead. Do not ream with the same pumping rate as used for drilling as it may create a 'mud ball' ahead of the bit. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . When heavy reaming is encountered. as cuttings/cavings must still be removed from the hole. reaming is to be done using 50 . 13. NB Stab. (Compare MWD data with plotted hole direction). the string should be picked up at frequent intervals and lowered to check if it is possible to wash the string past the tight spot. as there is a danger of side tracking the hole. When excessive reaming is anticipated. Stab. at least the last 60 feet has to be reamed before drilling ahead with the next bit. Use a semi stiff assembly e.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING velocity. With a jet bit. This gives rise to difficulties in log interpretation. care must be taken to minimise washouts and avoid bad primary cementations. the solids build-up in the mud may cause problems. 3. With excessive reaming. etc. to prevent likely hole problems. 2. Care should be taken to prevent drilling a new hole in a directional well.3. g. diverging T&D. excessive ECD. limited cuttings returns).SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 9 of 24 13. cuttings beds tend to slide down the low side of the hole and may accumulate. c) >±60° degree wells: Hole cleaning practices should be designed to move cuttings in a long. once cuttings have fallen to the low side and cutting beds formed. Prior to any back-reaming on trip out. the better the hole cleaning will be.5 HOLE CLEANING One of the major problems in SPDCs drilling operations is stuck pipe due to "Hole Pack-Off" (due to solids). This is because the flow approaches turbulence and stirs up the cutting beds with a scouring action. Cleanup cycles are not a waste of time “Sometimes you have to go slow to go fast” EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . then low viscosity fluid pumped at high annular velocity combined with rotation of drill string at very high speeds will have effect. the problem can be alleviated by keeping the hole as clean as possible. Prior to drilling into a known or suspected loss circulation zone. This is common in highly deviated and horizontal holes with inclination greater than 350. b) ±35° to ±60° wells: Hole cleaning practices are designed to combat cuttings avalanching. Boreholes become more difficult to clean as the angle increases. However. Mud rheology (viscosity) has a great effect on the hole cleaning in vertical wells. 13. Appropriate hole cleaning approach must therefore adopted depending in well bore inclination a) 0° to ±35° wells: Mud rheology & flow rate are designed to keep cuttings in suspension and combat slip-velocity.1 WHEN IS HOLE CLEANING REQUIRED? In general hole cleaning cycles are mandatory at any of the following stages: Prior to any trip out of the hole! For remedial hole cleaning when a hole cleaning problem is evident (e. During back-reaming if signs of packing off are seen. At high angles. the higher the viscosity. stationary bed (with a short avalanche interval in the build section) Note that a high angle wells must deal with each of these intervals.5. causing the hole to pack-off. where it may be said that in general. particularly by using sufficient mud density to delay the onset of borehole collapse. Whilst some actions can be taken to reduce the occurrence of unstable hole. Do not stop pumping till the sweep is completely out of hole.2 RECOMMENDED HOLE CLEANING PARAMETERS (FOR HIGH ANGLE WELLS) Desirable for Good Hole Cleaning Minimun for Effective Hole Cleaning Flowrate (gpm) Drillstring rpm Hole Size Flowrate (gpm) Drillstring rpm 17½” 14½” 12¼” 9 7/8” 8½” 900 – 1200 850 – 1150 800 – 1100 700 – 900 450 . carefully document to avoid doing the same thing twice and expecting a different result.5. ECD and torque 13.400 120 120 120 100 60 In all cases keep close watch over string vibration.700 500 350 .5. The number of BU will increase with: Increased measured depth Higher inclination Larger hole size Reduced parameters (rpm.5. Pipe should be rotated continuously at 120+rpm in hole sizes >9⅞”.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 10 of 24 13. viscosity) NOTE: The absence of cuttings over the shakers does not mean that the hole is clean.600 120 – 150 120 – 170 150 – 180 120 – 150 70 – 100 800 800 650 . flowrate. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . Consider alternative sweep types such as Tandem lo-vis / hi-vis sweeps and weighted sweeps.3 HOLE CLEANING CYCLES Generally a minimum 2 or 3 x cleaning cycles or bottoms up (sometimes up to 4 to 6) is required to cleanup a high angle hole. Experience has shown that cuttings usually come in two or more waves over the shakers 13.4 PUMPING SWEEPS When sweeps are pumped. time should be taken circulate the hole clean and the section "controlled" drilled (if directional constraints allow). Minimise nozzle velocities to less than 300 ft/sec. as evidenced by increasing torque and drag or insufficient cuttings on the shakers. If directional constraints allow. Viscous/high density sweeps are most effective in vertical and low angle holes and in removing larger or heavier cuttings and cavings. the procedure in item 9 should be followed after oriented drilling (sliding) with a downhole motor. when drilling soft or unstable formations. the ROP must be restricted. 8. if the hole is not cleaned.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 11 of 24 13. Note: Low viscosity sweeps are especially effective in deviated holes by stirring up the cutting beds and in removing smaller cuttings from washouts. washing and reaming down and pumping out. If in doubt. sufficient to clean the hole. The required annular velocity to clean a 50. During fast drilling. minimising the chance of packing off. as inadequate hole cleaning will increase the chance of the hole packing off. This may be up to twice as long as gas bottoms up. the string should be pulled off bottom and reciprocated whilst rotating as fast as possible for five to ten minutes whilst circulating prior to a trip. in general. In high angle wells (>45 deg. If losses are encountered.) high rotary speed. Therefore. the pump rate should not be reduced. Also. It is vitally important to rotate the string to move the cutting beds. 5. 6. Use cuttings bottoms up for circulating clean.5 GENERAL RULES OF THUMB 1. 2. is effective in "stirring up" cutting beds and improving hole cleaning.degree angle hole is double that required cleaning a vertical hole. drilling must be interrupted whilst the screens are changed. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . Check the effect of weighted/unweighted sweeps on the hydrostatic pressure. up to 180 RPM if possible. pump a low/high viscosity sweep and check returns. This will reduce the cuttings volume and spread them evenly throughout the annulus. A minimum flow-rate must be maintained when drilling. 7.5. The volume and physical appearance of the cuttings arriving at the shakers should be closely monitored to assess hole-cleaning efficiency. 3. 4. in deviated or washed out holes. the increased annular cuttings loading will often increase the ECD and exacerbate the losses. 9. On no account must the flow-rate be reduced. If the shaker capacity is overloaded and surface losses are occurring. particularly whilst pumping any mud sweeps. If this is ineffective. Sweeps should fill 300 feet of the annulus if possible. time consuming problem. wipe the hole at full circulating (5 . Very necessary for real time hole cleaning 3 4 Very important to clean the hole while the cuttings are being generated. raise the drill string slowly (5 min/std) and slack-off at a safe but fast rate (1 min/std) Select optimum rheology and maintain mud properties in optimum range Consider pumping high-vis sweeps in wells at low deviation (<35o).6 STUCK PIPE Pipe sticking is an expensive.5. or a combination of causes. to see if the annular velocity is sufficient and the mud rheology is suitable. Trip may be done with a different BHA. lower or rotate the drill string due to one.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 12 of 24 10. "ABC of Stuck Pipe" (EP93 – 1908 and EP94-1908) EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . it should never be necessary to pump sweeps in order to be able to continue drilling. 13. Mud sweeps should be used as a check on hole cleaning. It is defined as the inability to raise. 13. Consider low-vis / high-vis sweeps in wells at higher deviation (>35o) Must be done with the minimum recommended rpm and mud flow rate. Further information can be found in the Drilling Engineers Notebook. rotating at maximum RPM when possible Back reaming REMARKS This should be done/attempted on a best endeavours basis Mandatory for intervals drilled in the sliding mode.6 HOLE CLEANING BEST PRACTICES IN HIGH ANGLE WELLS BEST PRACTICE Use of adequate pump rates at all time REMARKS Minimum flow rates for different hole sizes as recommended in section 13.5.2 is mandatory Minimum drill string rotary speed for different hole sizes as recommended in section 13. Usually more difficult after cuttings bed has formed 5 For hole cleaning purposes.10 min). Be aware: Use of sleek BHAs can mask the presence of cuttings bed on the trip out. which can lead to loss of equipment.2 is mandatory 1 2 3 4 Use maximum practical RPM.5. side tracking and some times complete loss of hole. use backreaming only as a last resort. 1 2 BEST PRACTICE Plan the well with minimum possible build rate and during drilling minimize DLS to < 4o / ft Plan a reaming/wiping trip if hole geometry exhibits high DLS Short trip frequently every 500ft to 700ft depending on hole quality Before connections. 6. etc.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING 13. reactive formation. When differentially stuck. the problem is "one way" and in most cases occurs when pulling out. micro doglegs and mobile formation. but also fluid loss. it covers all the causes related to hole configuration and not those related to hole cleaning. Maintain mud properties within the programmed specifications. It should be noted that the pipe needs only to be stationary. the contact area and hence the sticking force will increase with time. key seating. Increase mud inhibition or encapsulating chemical concentrations if the cuttings become sticky or show a tendency to break up and disperse. the greater the contact with the pipe. particularly mud density.2 PREVENTION OF STUCK PIPE a) Mud Properties 1. the thicker the cake. 2. c) Solids/Hole Pack-off This category encompasses stuck pipe caused by cuttings. mud properties. The common observations for the stuck pipe causes in this category are that circulation is often restricted. hole collapse. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . Hole cleaning is difficult in a washed out hole and continuous generation of cavings makes efficient hole cleaning very difficult. Therefore. for a very brief period such as a connection change for it to get stuck. time spent circulating at the shoe to condition the mud could prevent loss of the hole.1 STUCK PIPE MECHANISMS a) Differential Sticking CHAPTER 13 Page 13 of 24 This is a sticking force which develops when the mud's differential pressure (overbalance) forces stationary Bottom Hole Assembly (BHA) onto the thick filter cake across a permeable zone. The common aspects of these causes is that once the string is stuck. which are often related subjects and affected by mud properties (mud density. fractured and faulted formations. Possible causes are under-gauge hole. Also. inhibition. ledges. length. the problem occurs when moving the string and it is often "one way" either coming up or going down.6. circulation is not affected. b) Mechanical Sticking/Hole Geometry This category of stuck pipe occurs when the hole diameter and/or angle relative to BHA geometry and/or stiffness will not allow passage of the drill string. circulation remains unaffected but pipe movement is not possible in either direction. BHA configuration is also of key importance.e. cavings. and stiffness of the BHA. It has to do with hole cleaning and hole stability. In general. filter cake thickness and mud solids play a significant part in differential sticking. rheology). 13. i. Thickness of the filter cake will affect the sticking force. OD and stabilisation. Consider using HWDP or smaller diameter DCs. circulate the hole clean of cuttings and cavings and when tripping. include a jar and use spiral DCs (the minimum required). 9. avoid excessive jet velocities as these will contribute to washed out hole. particularly in depleted sands. Never keep the pipe stationary in open hole. Prior to tripping. Ensure shift Drillers leave detailed handovers at the end of each tour. (0. If pumping out is necessary. 6. 6. consider rotating the string during a connection change. After increasing mud density. the DS must be on the rig floor for at least the first 10 stands pulled. Always wash/ream the last two joints to bottom. 4. do not decrease it. Use the top drive. 5. circulate at intervals to prevent the hole packing off. 5. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . it takes an increase of 0. b) Procedures: 1. increase in hole angle. Monitor torque.5 lbs. ensure that it is carried out before entering the problem zone (i. whenever tight spots are encountered and for the last 10 stands in. the overpull should be increased in 10 kips increments and always keep going back to where the string was free. 8. 7. not reactive. When the mud density has to be increased to control unstable Shales in known problem areas. Should the hole conditions dictate that an increase in mud density is required. Maintain good hydraulics when drilling.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 14 of 24 3. which may help the next Driller during a trip.allow for this when circulating clean. 4.026 psi/ft. 2. or areas of known differential sticking problems.e. but use high enough annular velocities to clean the hole. When working the pipe. 3.) be proactive. highlighting any hole problems.) mud density to stabilise the hole for each 30 deg. As a rule of thumb. "Bottoms up" time is greatly increased with hole deviation due to the cuttings settling on the low side of the hole . Use melon shaped stabilisers whenever possible and always gauge the bit and stabilisers when out of the hole. or install the kelly at any stage./gal. Not more than 90 ft of DCs in 12-1/4" hole section should be run unstabilised. Minimise the BHA. do it without delay. reduce the ROP to allow the mud to clean the hole. do not pull more than half the DC weight below the jars. as this will contribute to borehole instability. If shakers become overloaded. drag and carry out wiper trips if necessary. When tripping. 4 FREEING STUCK PIPE The first actions taken when the string becomes stuck have the greatest chance of success. in highly deviated wells. Plan ahead. mix and pump a spotting pill. hole deviation will result in less reliable values due to hole friction. This is a more accurate method than the stretch method. If differential sticking is suspected. using the jars if necessary. Even if the string is not differentially stuck. Using the formula. If the string was moving immediately prior to being stuck. move in the opposite direction. the EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . 4. 13. Analyse the type of sticking mechanism. By applying stretch and torque on the pipe.6.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 15 of 24 11. pull to the maximum and commence jarring. in remote locations keep the back-off equipment on site. work right hand torque into the string and slack off. the FPI run in tandem with a CCL can be used to accurately determine the free point and the deepest tool joint for back off. pull in lbs Wdp = Plain end pipe weight in lbs/ft b) Free Point Indicator Tool (FPI) The FPI is run on electric wireline inside the pipe. However. know the maximum load that can be pulled. 3. 13. as a correct interpretation will greatly increase the chances of success. consider including a drilling accelerator in the string. It should be the same as density as the mud and the volume should be sufficient to cover the BHA with enough excess to pump one bbl every half-hour for a 12-hour period. The recipe for a spotting pill should be known and the required chemicals on site. 1. 2. Immediately the string becomes stuck.3 DETECTION OF STUCK POINT Detection of the stuck point is necessary in order to find the deepest possible place for a back off. for a more accurate depth of the stuck point. use the wireline Free Point indicators. an approximate depth of the stuck point can be obtained. a) Stretch Method The stuck pipe is stretched and marked accurately at surface. An approximate depth can be determined using the stretch method. L = 735294 x Wdp x e P Where: e = Elongation in inches L = Length of free pipe in feet P = Load.6. Work the pipe to its limit immediately. Ensure that contract personnel are aware of the correct procedures. If unsuccessful. as soon as possible. the elevator should be latched around the pipe but should be free from the tool joint to enable free rotation. 4. consideration should be given to reducing bottom hole hydrostatic pressure. ensure there is no residual torque remaining in the string. It also has a detrimental effect on the mud and considerable mud conditioning will be required.24 hours. When torque is applied. When the string shot charge is run in the hole. 2. If differentially stuck. An explosive device is positioned by a CCL on electric wireline in the joint to be broken. 6. When the string is picked up. make sure that the hook is unlocked when the pipe is being rotated.6. 3. All precautions to control the well in the event of kick must be in place and the personnel warned in advance. 13. especially in crooked or deviated holes. This should only be carried out after discussions with the base SDE. ensure that only "one" of the table locks is engaged to make it possible to release the table after torquing up and firing the shot. When coming out of hole with the backed-off pipe. Strings have been known to come free half an hour or more after firing the string shot. 5. 6. check all connections for correct make-up torque. b) Working Left-hand Torque down the Hole It is necessary to work left-hand torque down the hole to the desired back-off depth. It is mixed using HCl and inhibitors and works by dissolving the filter cake and the formation. 7. treat the rotary table with great care. while applying pull for neutral weight at the back off depth. When the string shot has been fired and no positive indications of back-off is observed. sharp and of the correct size. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . 5. Tongs and back-up lines must be in good condition (double back-up lines are often used). tie the slip handles together to keep the slips around the pipe. Mud acid pills may also be considered. Where the kelly is in use. Tong and slip dies must be clean. Since there is a possibility that the string might part higher-up. a) Safety Precautions for String Back-off 1. All safety precautions must be taken when mixing a mud acid pill.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 16 of 24 spotting pill may prevent the string from becoming differentially stuck.5 BACK-OFF PROCEDURE The back-off operation (with strands of primer cord) consists of transmitting left-hand torque to the joint to be broken. The primer cord is detonated in the tool joint and the combined effect of the explosion and left torque unscrews the connection. plan to soak the string for 12 . section G. However. 13. Calculating the surface pull to achieve this force at the proposed back-off point is generally done assuming no buoyancy effect since the pipe is held down.6 REPORTING The "STUCK PIPE REPORT". slips and elevator can be used with great care.7. To get the maximum jarring effect. Kelly. Hydraulic jar.7 FISHING AND JARRING OPERATIONS All fishing operations are classified as lost time and as such should be dealt with as quickly as possible. all efforts must be made to ensure losing the fishing string does not compound the fishing problem. the buoyancy effect will act on the freed string. 13. the "FISHING REPORT" and the "EVENT ASSESSMENT REPORT" must be completed after these incidents. Always have a range of overshot bodies and grapples for fishing all tubular sizes in regular use. the same amount of DCs as left in hole should be run on top of the jars. this is difficult to achieve and it is better to have the joint in slight tension rather than compression. DCs. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . endeavour to have the correct fishing equipment on site. However. The tool joint to be backed-off should have a zero load. hang the string off on the pipe rams. Working torque down the hole using rig tongs is ineffective and dangerous. If the drill string become stick whilst round-tripping or making a connection.1 GENERAL PRACTICES The standard fishing assembly is as follows: 1. The calculation of required pull is outlined in the Drilling Engineering Notebook. remove the top single and install the kelly. 2. Well Equipment Specialist and the Performance management Co-ordinator in order that the data can be utilised to prevent further incidence of stuck pipe. Overshot. Fishing jar (18 inches stroke). Use mechanical jar only if hydraulic jar is not available. the Kelly must be installed with the bushing in the rotary table. When non-routine operations involve different sized tubular. Where the kelly cannot be installed. A jar accelerator can also be run on top of the drill collars. 13. If after several attempts a back off cannot be achieved. however in practice.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 17 of 24 In order to work the torque down. Always try to use the kelly. as soon as the joint is cracked. this is especially recommended in deviated holes or when fishing at shallow depth.6. Ensure they are completed accurately and in full and submitted to the SDE. DP. consideration should be given to running the Schlumberger Colliding tool or a similar device. Do not run a safety joint with a fishing assembly because experience has proved that jarring on a safety joint freezes it and makes it useless.7. torque up the string to the right from time to time. Prior to pulling out any fish. 4. as left-hand torque cannot be applied to the string. heavy pulling and jarring must be done with the Kelly added to the string. 8. 9.000374 x Weight of DCs above Jar x Overpull = Impact Force in lbs. 5. Never use an 18 degree shoulder elevator for jarring. wherever possible. all connections must be checked for correct make up torque. 7. especially when fishing tubing or thin walled pipe. When jarring. do not exceed the impact force recommended by the manufacturers. the elevator latch should be secured with rope or chain. Avoid washing out the hole just above the top of fish as this could cause difficulty in latching onto the fish. When fishing stuck tubing. When pulling a fish. When jarring with a jar close to surface. it will not be possible to use a string shot for back off. The following formula will give the theoretical impact: 0.2 USE OF FISHING TOOLS a) Drilling Jar 1. This is to reduce incidence of the bigger OD tools above the jar getting stuck and rendering the jar useless. circulate bottoms up to ensure no gas is trapped below the fish. a jar should be placed at the top of the drill collars with one drill collar above it. Always use a basket grapple in preference to a spiral grapple. 2. whenever possible. particularly packers. 6. As a rule of thumb. 10. Where this is not possible. For rigs that use Kelly. When heavy jarring has been done. the pipe should not be rotated out and any working of the string should not be above the maximum yield of the pipe. circulate the hole clean and spot a viscous pill before pulling out of hole. The drilling jar should never be positioned below tools with a greater diameter than that of the jar. 3. always use a square shoulder and EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . When a twist off occurs. fish on collars or connections as less deformation to the top of the fish occurs. Wireline re-entry could be required at a later stage and this may be difficult if the tubing is deformed. 13. Refer to the Drilling Engineers Notebook for additional information on the correct fishing tools to have on site depending upon the hole size being drilled. Also.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 18 of 24 3. to avoid premature back-off. 9. 2. Never run a jar in the neutral point. The overshot is the most common fishing tool to externally engage.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING the correct elevator.4 hours of jarring. Never run jars immediately below a crossover. 6. The Bowen overshot commonly in use in SPDC requires right hand rotation for engaging and releasing. If the hole drag is close to the tripping weight of the jar. This could cause the slips to jump loose in the rotary. Note that strings could be plugged with cuttings after a drill string failure while drilling. When the drilling jar connection has to be broken. 4. pack off and pull a fish. the jar should be in tension during drilling unless using a type of jar recommended to be run in compression. no pack-off element must be used in order to allow for circulating bottoms up prior to POH. b) Overshot 1. (String has been known to jump out of the slips). 7. etc. The pull to trip a jar = original weight indicator reading + the jar trip setting (this is an acceptable rule of thumb). a detailed drawing including all external and internal dimensions must be made of the complete fishing assembly. the overshot must then be run over the fish to about ½ ft above top of grapple. 5. This is valid for running in and pulling out. This is because the momentum of the drill collars below the jar can create enough left-hand torque in the jar to cause it to trip. 8. CHAPTER 13 Page 19 of 24 4. either by weight decrease or pressure increase. It is very simple to engage and disengage from the fish when desired. This is to enable fishing EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . When there are hydrocarbons below TOF. Prior to running an overshot. Whenever possible. two tongs should be used if the jar is in a cocked position. Slip block line after every 2 . 3. and always follow manufacturer's operating procedures. Use a safety clamp around the jar to prevent the jar from tripping in the derrick. 6. Regularly check the derrick and lifting equipment for loose bolts. Jars should always be run at least 30 feet above any reamer/stabiliser to allow the jar to flex. When Top Of Fish (TOF) is located. Do not use an overshot with a much larger OD than required. 5. This will avoid "butting out" of the fish in the overshot and ensure that there is sufficient room inside the overshot to come off by beating down. care should be taken and a "wait period" must be exercised prior to releasing the elevator for changing a connection. 9. followed by rotating to the right and picking up. If any form of wireline work (e. it is important to core approximately 6 inches and then pick up string to allow junk on the side of the wall/basket to fall into the pilot hole. ensure that the complete fishing string is drifted with the appropriate drift. Maximum length of core depends on the size of the basket but it is usually 1-1/2 to 2 feet. followed up by picking up to engage fish internally. ensure that all dimensions are known and string weight up and down should be checked as well as the circulating pressure. If an overshot is to be used for mechanical back-off. string shot for back off or severing of pipe) is envisaged. strapping of the overshot bowls may be necessary to avoid backing off on the fine threads of the overshot. before engaging the fish. The standard assembly for a spear is as follows: Spear. Before running a spear.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 20 of 24 the overshot itself if it parts in the process (e. then install a surface jar (4-ft stroke) and jar down. knock down on the slips by applying a quick slack-off. as this EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . e) Spears The spear offers an easy means of engaging a fish internally. When releasing a spear. Engagement of the fish is done by turning the string a quarter to the left. The 4 ft surface jar and 3 ft downhole jars are chosen. To release from the fish when desired. Kelly (for rigs without TDS). Fishing jar (3 foot stroke). This gives an upward blow of higher impact than can be obtained with only the jar. It should be placed in the HWDP section of the string. 8. overshot with a small OD could go past TOF unless an oversize guide shoe is run. or at shallow depths. if knocking down does not free it. the string weight up and down must be established. 7.g. Before locating the fish with an overshot. (this disengages the slips). d) Junk Sub/Jet Junk Retriever A junk sub can be used to recover junk such as lost cone inserts. DP. When using a jet junk retriever for recovering junk. This ensures that it can be recovered when coring is continued. The small junk is jetted from the bottom of the hole and rises sufficiently before falling into the junk basket. 5-3/4" overshot can be fished with a 77/8"). DCs.g. On the other hand. c) Jar Intensifier or Accelerator The function of the intensifier is to supply acceleration to the upper end of the jar during jarring. The accelerator is valuable in deep and crooked holes where much of the stretch of the string is lost in friction. If drilling indicates that there is junk on bottom which cannot be broken and recovered in the junk sub.7. putting the pipe into plastic loading and causing permanent deformation. it is always necessary to trip the jar prior to pulling to desired maximum pull. run in with a conventional hard formation rock bit. They are based on minimum yield values and do not include any safety factors. this spear is easily released by torque.4 ALLOWABLE PULL ON DRILL PIPE When determining the pull on stuck pipe. drill a few feet. premium and grade 2 drill pipe. continue as per programme. the following values. 13. and recommendation based on API RP7G. Whenever loads are pulled close to maximum.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING combination enable the down hole jar to close completely before the surface jar. Section C in the Drilling Engineers Notebook gives values for the maximum tensile load on new. the actual weight of the string in air is to be used and not the buoyant or weight-indicator weight. should be followed: a) Classification of Grade For Tension Premium pipes 2 . as this constitutes the weakest point in hole.7. ensure that the rig floor is clear of unnecessary personnel. Rotate and circulate several times along the hole sections where the bullets were lost to attempt to dislodge the bullets from the wall of the hole. CHAPTER 13 Page 21 of 24 The Bowen ITCO spear can be run with a stop ring.3 FISHING FOR CST (SIDEWALL SAMPLE) BULLETS If bullets from a CST gun are lost in hole. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . fish for junk. When on bottom. Failure to trip the jar before pulling may result in additional dynamic loading which could exceed the elastic load limit. pull out and run a reverse circulating junk basket to fish for the junk. It is advisable not to pull more than 80% of the quoted values. 13. If no significant torque is encountered. 20%) and minimum wall thickness of 80%. Do not continue drilling with junk sub. Whenever maximum loads are pulled on the drill string and a drilling jar is included on the BHA. For Torsion New : Premium : Direct from factory DP having uniform wear (max. Drill Stem Design and Operating Limits. with not less than 3 x 18 nozzles and a junk sub. Where pipe is stuck and jarring or a straight pull is necessary.20% uniform wear. If exact volumes are known. When mud is highly treated with lignosulphonate. The "equalisation point" formula is: N -------------C+T OWNER EPG-PN-W CUSTODIAN EPG-PN-WT h= EDITION REV 04-2007 . For good placement of a balanced cement plug. it is better to set two short plugs over the washed out interval than to try to cover the complete interval with a large amount of cement.8. use it to calculate the required volume. which may result in heavy backflow or a poor quality cement plug. Run a tubing stinger on drill pipe to the desired depth of the bottom of the plug to be set.8 PLUGGING BACK AND SIDETRACKING OPERATIONS CHAPTER 13 Page 22 of 24 13.04 SG)] If a calliper log is available. A hole is plugged back usually by setting a cement plug.88 psi/ft (2. Use a water-spacer ahead and behind the cement slurry and avoid stabbing the stinger back into the cement plug when displacement is completed. (which acts as retarder) ensure good scavenging and separation ahead of the cement slurry and allow for uncertain setting time. 13.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING 13. fluid loss control additive is used in the cement slurry to give a water loss of less than 50 mls. 0. there is little alternative other than to plug back a section of the hole above the fish and then sidetrack the fish. the integrity of the plug must be confirmed with a pressure test and an inflow test. To prevent cement slurry dehydration and consequent flash setting when plugging back over very permeable sand. If the section is to be plugged back into the casing and it is planned to reduce the mud hydrostatic pressure to less than that of the highest formation pressure drilled.2 SETTING A BALANCED CEMENT PLUG 1. The length of the stinger should be equal or greater than the height of expected column of cement.g. 2. Always ensure there is about 600 ft of such tubing on site. use a balanced water spacer column ahead and behind the column of cement. often by using dense slurry [e.1 GENERAL If a bottom hole assembly or logging tool cannot be recovered economically. It is common in SPDC to set cement plug using 2-7/8" or 3-1/2" tubing stingers. If the hole is badly washed out. use theoretical volume for balanced displacement. The cement formulation should be such that a hard plug results.8. Note that the top of cement must be confirmed with a bit. When height of cement column in the string plus the height of water spacer behind is subtracted from the string length. Chase with mud (or brine) until the cement. A kick off is most successfully carried out using a mud motor and a MWD. relief-well or any zone of interest.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13 Page 23 of 24 Where: N = Volume of cement slurry used (in barrels) h = Height of balanced cement column (in feet) C = Barrels per linear foot of space between tubing and casing (or hole) (i.e. water and mud columns in pipe and annulus balance. the cement may be under-displaced by the displacement volume of the stinger). annular capacity between stinger and hole in bbls/ft). use the cement pump for displacement. 6.8. the displacement volume can then be accurately known.000 ft above top of cement and circulate out excess cement. Pump the calculated water ahead for effective scavenging. For small plugs and accurate placement of small volumes. 4. capacity of pipe or stinger in bbls/ft).3 SIDETRACKING Sidetracking is a way of diverting the course of a well from a fish or a wrong course. hard plug be obtained to give a definite kick-off. (To prevent 'wet' tripping. Prior to running the KO assembly. to a required target. EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . the cement plug should be weight tested to 30 kips and dressed to the desired kick-off depth with a bit. T = Barrels per linear foot inside tubing (i. 13. mix and pump the desired cement volume. Note: Use dense "neat" cement with tight fluid loss control (in open hole) in order that a firm. then pump the water behind to balance the column of water ahead. 3. 5.e. Pull back until the pipe is at least 1. : TELEPHONE: Please dispatch form to EPG-PN-WTE (Technical Standards) EDITION REV 04-2007 OWNER EPG-PN-W CUSTODIAN EPG-PN-WT . Any other suggestions or comments NAME: DEPT. What is not required? 7. Too many or too little detail 5. Adequacy of reference 4. Any inaccuracies or confusion in the text 2. What is missing? 6. Ease of finding information 3.SPDC STANDARD DRILLING PROCEDURES MANUAL HOLE PROBLEMS AND FISHING CHAPTER 13: Hole Problem and Fishing FEEDBACK FORM CHAPTER 13 Page 24 of 24 Use this form to communicate: 1.