Carbonate Complexity : Characterization, Modeling and Simulation April 22nd – 25th, 2008, Yogyakarta, IndonesiaCarbonate Reservoirs – Challenges in Facies Modeling & Fracture Characterization By Subrata K. Chakraborty Mega Ardhiani Puspa Schlumberger Data Consulting Services, Jakarta Contents • Introduction • Facies Modeling of Carbonates • Fracture Characterization of Carbonates Carbonate Reservoir in Indonesia Arun Vanda Natuna DAlpha Serang Ara Salawatir Klalin Oseil Walio Oil Production in Carbonate vs Clastic from Indonesia in 1976 Rawa Ramba Kampung KajiKrisna Baru Bima Semoga Bawean KLY Air Serdang Kangean Krisna Poleng Rama Ujung Pangkah Klamono 92% 8% Ref. : Warren C Leslie Worldwide 60% HC in Carbonates, in ME 75% Field Arun Ramba, Rawa, Soka, Kaji-Semoga Air Serdang, Mandala Bima, Rama, Krisna, "AA", Selatan, Kandanghaur Timur, Arimbi X, Yvonne, Nora, Kitty, Cinta, Gita Arjuna FF, Arjuna FZ, Pondok Tengah, Tambun L structure Carbonate complex 80-6 Limestone, CN-9 zone Vanda Limestone Kangean PSC, Poleng Poleng, Ujung Pangkah, Jaya, Bawean, JS Randublatung, Kedunglusi, Kedung Tuban Oseil Basin North Sumatra Basin South Sumatra Basin Formation Arun Limestone Batu Raja Age Early Miocene Lower Miocene Sunda East Natuna/Sarawak Basin Kutai Basin Tarakan Basin East Java Basin Seram East Sengkang Basin Salawati Basin Batu Raja Natuna D-Alpha block Serang Vanda Ngimbang Kujung Manusela Late Oligocene-Early Miocene Mid - Late Miocene Late Miocene Late Miocene-Early Pliocene Mid-Upper Miocene Late Oligocene-Early Miocene Early-Middle Jurassic Lower Miocene Miocene 60 Carbonate Fields Tacipi Limestone Kampung Baru, Walanga, Sampi Sampi Kais, Textularia II, "U" marker Kasim, Walio Cendrawasih, Moi, Jaya, Kais Klamono, Linda, Sele, Salawati A,C,D,E,F&N Arar, Klalin, Kasim Utara, Kasim Barat Part-I Facies Modeling in Carbonates . Regional Carbonate Depositional Model Carbonate Ramp Model Rimmed Platform Model te na o ?? Ba j Ra tu rb Ca a . Stratigraphy – South Sumatra . Facies Modeling-Workflow Facies Modeling Facies Interpretation At Wells Core Facies Most Definite Limited Vertical Distribution 3D Modeling Image Facies More Definite Reasonable Vertical Distribution Electro Facies Less Definite Wide Vertical Distribution Result depends on Log Availability Seis Facies Least Definite Wide Aerialal Distribution Limited Vertical Resolution Results depend On data quality Pixel Based Works well with good quality Seismic Data & Good Well Density Object Based Works best With Knowledge of Paleo-geography & Paleo-environment Used Mostly For Calibration Most Widely Used Less Widely Used 3D Facies Model . Neural Network was trained with above core facies where key logs showed significant variation for different facies type and Supervised Neural Network was run. RHOB. “Petrel-Make Log” utility was used to generate trained electrofacies in other wells having the key logs. Generated electro facies in each well was examined and corrections made by editing wherever required. . PHIE used as key logs for Neural Network based facies Electro Facies Interpretation in “Petrel”.Facies Interpretation – Neural Net Based Approach 9 originally identified Carbonate sub-facies narrowed down to 4 Carbonate Facies from fluid flow behavior point of view. Deep water Shale Facies Tight Platform Facie Coral Rich Wackstone & Packstone Reworked Skeletal Facies VCALY. the result is summed and the result passed through a non-linear function to produce the output. Each input is multiplied by a weight.Neural Network Training Neural Network : An algorithm that takes multiple log inputs and returns one or several outputs. It is of two types – “Supervised or Trained” (Sigmoidal Basis Function Regression Network) or “Untrained” (Competitive Selective Learning). Electro Logs Electro Logs in Training Facies Correlation Analysis : Neural Network – BRF Carbonate Facies . BRF Carbonate 3D Facies Model – General Workflow Facies Model Object Based Model “Stochastic Object Modeling” Algorithm Well Data Guided by Object Trend Facies Interpretation in Wells as Logs Upscale Logs to Model Cells Data Analysis Vertical Proportion Analysis Variogram Analysis Facies Modeling Object Based Identification of Depositional Elements (Objects) Hard Data : Facies Log Interpolation Guide : Objects Q/C Progradational Line Reef Trends Reef Geometry . Reefal Facies Object Modeling . . The 3D Facies Model becomes the basis of modeling other reservoir properties.SUMMARY Developed 3D Facies Model captures the Field Carbonate Geology. Part-II Fracture Characterization of Carbonates . A fracture is a commonest type of geological structures and may be seen in any rock exposures. There are two kinds of fracture: (a) Joint : no displacement. (b) Fault : has measurable displacement across the fracture plane A – Breccia Clasts B – Breccia Matrix C – Open Fractures D – Healed Fracture E – Fractures filled with breccia material Core from Oseil-1 (Ref IPA 2002) “Carbonates” are more prone to fracturing than “Clastics”.Definition : Naturally Fractured Reservoirs are defined as formations in which the fracture permeability substantially enhances productivity. or displacement is too small to be visible. Dual Porosity – Permeability System OUTCROP EXAMPLE : Fractured Carbonates from Oman EXAMPLE From Cores . Youngs Modulus (E) is related to capability of storage of strain energy. fracturing intensity may be controlled by different carbonate facies present.Fracture number E = tensile stress / tensile strain E-Modulus high -> Flow Mudloss and rubble in cores – only seen in outcrop E-Modulus low -> Storage E = ca. In a carbonate reservoir. 90 GPa (low frac toughness) 400 E = ca. : Tyler 1988 Fracture toughness is regarded as being the opposite of Rock strength: A weak/ soft rock accomadate more strain before fracturing. 100 Dolomite Limestone Ductile Lithology Brittle Ref. 20 GPa Quartzite Sst. . Fractured Carbonate Rocks Carbonate Rocks are More Prone to Fracturing than Clastic Rocks. PVT properties remain constant throughout a fractured reservoir due to conductive circulation. High fracture permeability ensures rapid contact equilibrium even during production. if reservoir is properly managed. GOR of fractured reservoirs remains lower throughout during production.Difference of Fractured Reservoirs from Conventional Reservoirs High Transmissivity of Fracture Network – Pressure drop around producing well is low. Fracture reservoirs lack transition zones. OWC/GWC’s are knife sharp surfaces. Production is driven by complex mechanisms that governs fracture/matrix-block communication. : SPE 84590) . Water cut is strictly a function of production rate. (REF. fractures do not provide significant storage capacity or permeability in an already producible reservoir but instead create anisotropy.A. Haft Kel (Iran) 2660 MMBL.Fractures provide a permeability assist to the reservoir. 96955. 87238. UmLulu/Asab/Bab (UAE) (SPE 36228.Fractures provide the essential permeability to the reservoir. 97834) Type 3. Example : Amal (Libya) 1700 MMBL. (SPE 35309. 106986) Type 2. Example : Kirkuk (Iraq) 15000 MMBL. 102453. Example : Agha Jari (Iran) 9500 MMBL. 2002) Type 1. NWRA (Kuwait). Gachsaran (Iran) 8000 MMBL. 1999. Edison (California) 42 MMBL. Ellenburger (Texas) 108 MMBL. 62608.Fracture Reservoir Classification (After Nelson. Rangely (Colorado) 600 MMBL. La Paz/Mara (Venezuella) 800 MMBL. 65186.. Hassi Messaoud (Algeria) 6000 MMBL.Fractures provide the essential porosity and permeability to the reservoir. TaHe (China) (SPE 49221. . Dukhan (Qatar). 11164) Type 4. R. 5023. Water injection schemes may get jeopardized by preferential water front movement along fractures..If Fracture Porosity-Permeability is Not Modeled – Consequences ? Unexpected decline in from predicted Field Performance. early gas coning & water breakthrough reducing oil recovery.. In case of oil reservoir with active water drive. In case of thick gas cap & active aquifer. Severe mud loss during drilling of horizontal wells aligned across unfriendly fractures. Improperly aligned horizontal wells may have low productivity.. Thin Oil Column in Fractured Reservoir . Field Recovery Curve Recovery Factor Gas Cap Oil Column Water Fractures So. it is Important . early water breakthrough reducing oil recovery. Fractures in strike slip area will be concentrated near the master faults and is 60o offset to the strike slip fault. Extensional System.. Collision of Plates . e. e..g. Rifting & Drifting of Plates Left lateral Strike Slip System.g. Fractures in compressive area will be concentrated on the anticlinal bent areas of the folds and will be perpendicular to the direction of maximum compressive stress. e.Fractures & Tectonic Style Tectonic styles and fracture type identified to three plate boundaries : Divergent (tensional – normal faults) Transform (shear – strike slip faults) Convergent (compressive – reverse faults) Fractures in extensional area are parallel to the main fault. rotation of plates Microsoft owerPoint Presentatio Compressional System.g.. world-stress-map. hence in Indonesian fractured reservoirs fractures having fracture sets of this orientation are likely to be more “Open” in general (Leading Edge 2005).org/ World stress map of Austral-Asia Plate . http://www.Effect of Present Day Stress Field on Faults & Fractures In Indonesia the dominant present day maximum horizontal stress direction is NE-SW. Fracture Modeling – Workflow (“Petrel”) Interpreted Image Logs Fracture Modeling Input Data Ant Tracking Fault from 3D Cube Tadpole Rose Diagram Create DFN Create Fracture Property Upscale Fracture Property Volumetric Estimation Stereo Net Analysis Display & Analysis Create Intensity Log Model Intensity Log Create DFN Create Fracture Property Upscale Fracture Property 3D Display Well Section Advanced Options of Using Collocated Co-Krigging Uncertainty Analysis . Fracture From Image Log Conductive Fractures : Assumed open Resistive Fractures : Assumed sealed Interpretation is done for Conductive Fractures Basic Fracture Analysis Data Apertur e Azimuth Dip Fracture Density/ Intensity Log Tadpole Fracture Advance Fracture Analysis Data Aperture Density Porosity Fracture . Fracture Interpretation from Array Sonic Logs FMI Log Array Sonic Quantitative Tool Qualitative Tool Shallow Penetration Deeper Penetration . Rose Diagram helps to understand fracture orientation and sets. Stereo-net helps to understand fracture dip angle and azimuth. .Fracture Analysis – From Image Log Data Tadpole & Rose Diagram Display Stereo-net Display & Filtering Rose diagram showing dip azimuth Rose diagram showing dip azimuth Intensity log Tadpole Fracture Intensity from Image FractureLog Intensity Log Tadpole Fracture log Tadpole Helps to understand fracture Intensity and orientation. After Nelson 1999 Field-X Aerial Distribution of Rose Diagrams brings out the Imprint of Different Tectonic Events Clearly . 3D Modeling of Fracture Intensity Creation Create Intensity Log Upscale Intensity Log Model Intensity Log Created from the fracture set Upscaling Modeling Fracture Intensity Cube . Create Discrete Fracture Network (DFN) Orientation Distribution Fracture Orientation Fracture Intensity Fracture Density Geometry Fracture Length . dip and length. Discrete Fracture Network (DFN) Real Life Analogue .Analysis of DFN Stereonet Display Consists of no of fractures of certain orientation. 3) Output Fracture Porosity Permeability Tensors (I.Create Fracture Attributes Aperture (Required for Fracture Porosity) By 3D Modeling By Calculator Operation Fracture_length=Sqrt( Surface_area) Aperture=Fracture_length*Normal( 0. j & k directions) Sigma Factor (connectivity between fractures and matrix) . 0.005.0005) Upscale Fracture Attributes Oda Method Permeability (Fracture Permeability depends on “Aperture” & “Permeability”) By 3D Modeling By Calculator Operations Permeability=Pow( Aperture. 3D Fracture Modeling – From AntTracking Interpretation DFN Main Faults in 3D Model Ant Tracked Faults/Fractures Create DFN Create Fracture Property Upscale Fracture Property Create DFN From AntTracked Fractures . 3D Fracture Modeling – Secondary Porosity & Permeability Upscaled Fracture Ki Model Upscaled Fracture Porosity Model Upscaled Fracture Kj Model . using the Define Simulation case process. Matrix properties should be ready.Dual Porosity / Permeability Simulation Input Can be done in Petrel RE. and the fracture properties from upscaling should now be available. Matrix Poro/Perm Sigma Factor Fracture Poro Perm . Transient Well Test matching in “Green Field”. Explanation of higher production from some horizontal wells. Explanation of uneven injection water movement. early water breakthrough. Explanation of early gas coning.Validation of Fracture Model Difficult in “Green Field” compared to in “Brown Field”. Explanation of mud-loss in horizontal wells. . Dynamic history match data is the main data to validate model. East Java Sea ?? (Operator : Amerada Hess) . “Moi”. “Kasim”. East Java (Operator : Pertamina) “Pase A” Gas Field. “Kasim Utara”. Fractures related to Strike Slip movements. Salawati Basin. Eastern Indonesia (Operator : KUFPEC). “Arae” fields. “Cendrawasih”. Seram Island. North Sumatra (Operator : Mobil Oil Indonesia) “Darajat Field” (Operator : Amoseas Indonesia Inc) “Oseil Oil Field”. Fractures related to Collision Tectonics & Inversion. Pase PSC.Fractured Reservoirs in Indonesia Fractures related to Syn-Rift Tectonics. “Jaya”. Irian Jaya. “Ujung Pangkah”. Fractures related to Local Structuring (trap formation). Examples “Jatibarang” fractured basement. 25 my 20 my Talang Akar Syn Rift/Drift (Normal Fault) Batu Raja Carbonate Syn Rift/Drift (Normal Fault) Plate Tectonic Reconstruction of Sumatra & Java of Indonesia showing the active Syn Rift/Drift Phase (Likely Fracture Orientation NW-SE) . 12 my 09my Air Benakat Time Strike Slip Movement + End of Drift Structural Inversion Strike Slip Movement + Collision + Plate rotation Reverse & Strike Slip faults Plate Tectonic Reconstruction of Sumatra & Java of Indonesia showing the active Strike Slip Movement due to Plate Rotation and the Collision Phase (Likely Fracture Orientation N-S to NE-SW and NW-SE) . Data Acquisition Program for Naturally Fractured Carbonate Reservoirs FMI/Sonic Scanner Logs Advanced Fracture Interpretation FMI/Sonic Scanner Logs from Image Log High Quality 3D Seismic Data with acquisition optimized for Target Reservoir Sonic Scanner Logs Completion Fracturing might be necessary to Enhance Fractures Stage Frac Completion Assembly . Thanks for Your Attention .
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