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Cosan Ayan

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Reservoir and Fluid Characterization with Formation Testers: Reducing Asset Uncertainties

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Cosan Ayan

  1. 1. Primary funding is provided by The SPE Foundation through member donations and a contribution from Offshore Europe The Society is grateful to those companies that allow their professionals to serve as lecturers Additional support provided by AIME Society of Petroleum Engineers Distinguished Lecturer Program www.spe.org/dl
  2. 2. Society of Petroleum Engineers Distinguished Lecturer Program www.spe.org/dl Dr. Cosan Ayan, Reservoir Eng. Advisor Reservoir and Fluid Characterization with Formation Testers: Reducing Asset Uncertainties
  3. 3. Wireline Formation Testing (WFT) Applications Land and Offshore Pressures Sampling and Downhole Fluid Analysis (DFA) Transient Testing In-Situ Stress Testing Reservoir Characterization 3
  4. 4. Formation testing-evolution Early formation testers: circa 1956 4
  5. 5. Current Wireline and Logging While Drilling Formation Testers  Real time monitoring and control  Various downhole pumps  Various probes, including focused types  Downhole sensors:  Optical: contamination, GOR, composition, pH  NMR based  Density, viscosity, acoustic, refractive index, resistivity, capacitance  Various sample chambers, including single phase chambers 5
  6. 6. 28 Deepwater GoM Fields 6 Deepstar Industry Study (OTC 25173) 75 % Underperform on rate and recovery! Good reserves Goodproduction
  7. 7. From Measurements to Reservoir Modeling Single Station Analysis Single Well Analysis Multiple Well Analysis Understand Your Reservoir Pressure Fluids Transients Gradients & Contacts Multi Well Gradients & Contacts Multi Well DFA Prediction Common applications in land vs offshore. Offshore is more critical in exploration and appraisal stage7 MicroFrac
  8. 8. Pressures Sampling and Downhole Fluid Analysis (DFA) Transient Testing In-Situ Stress Testing Reservoir Characterization 8
  9. 9. Reservoir Characterization with Pressures/Gradients, offshore Free water level extrapolated from pressures recorded in the oil and water legs from two different wells )1( )1(121 222    KK K h Dp  Statistical Error. In this case = 0.012 g/cc Factors FWL error (ft) FWL Depth accuracy +78 up/down Pressure gauge accuracy +135 up/down Gauge temperature sensitivity −207 down Pressure gradient error (oil) +54/−112 up/down Capillary (water zone OBM) +7 up (Water Wet Sand)9
  10. 10. Gradient Errors: Effect on reserves, offshore field 10
  11. 11. Pressures Sampling and Downhole Fluid Analysis (DFA) Transient Testing In-Situ Stress Testing Reservoir Characterization 11
  12. 12. Effect of OBM on a near critical fluid 0 0.2 0.4 0.6 0.8 1 VolFracUpperLiq 0 0.01 0.02 0.03 0.04 0.05 VolFracLowerLiq 5000 6000 7000 8000 9000 10000 Pressure psia Expt. Uncontaminated Expt.5 wt % Novaplus EOS Uncontaminated EOS 5 wt% Novaplus GOM Near Critical Fluid 180 F CCE Phase Diagram 12 Exp. Uncontaminated Exp.5 % wt OBM Contaminated EOS Uncontaminated EOS 5 % wt OBM Contaminated
  13. 13. Contamination Cleanup Behavior Drains Saturn  3D numerical models were simulated: Miscible and immiscible (liquids)  Accurate representation of drain size and shapes  Proxy models generated from thousands of runs Time 1 Time 2 Time 3 Time 4 13
  14. 14. 10 -2 10 -1 10 0 10 1 10 2 10 -2 10 -1 10 0 Time [hrs] Contamination 5% contamination Saturn 3D Radial Probe XLD Probe Dual Packers 3D Radial Probe Tool Cleanup time (5%) [hrs] 3D Radial Probe 0.71 Extra Large Dimension Probe 9.10 Dual Packers 1.00 3 Dimensional Radial Probe Probe Dual Packers Contamination Cleanup Behaviour Slope = - 5/12 Slope = -2/3 1414
  15. 15. H2S in oil and gas industry and its consequences  Sulphur compounds in crude oil and natural gas exists in various forms  70% of crude oil and 40% of natural gas reserves are sour (IEA)  Sulphur content has been increasing in produced crude (OPEC) Commercial Impact Operational Challenges HSE Concern 15
  16. 16.  New sensor based on electrochemistry  Membrane for H2S diffusion between the flowline and measurement cell  Integrated measurements: • pH to correct for CO2 • Baseline concentration • Temperature Downhole InSitu H2S sensor Buffer + Mediator Electrode Bulkhead Membrane (diffusion)Fluid Flow with H2S Flowline Measurement cell Flowline Electrode bulkhead Membrane Sensing chamber Connector 16
  17. 17. Flory-Huggins-Zuo (FHZ) EoS to predict asphaltene content variation  Connectivity  Compartments  Tar Mats  Heavy oil  Compositional gradients  Disequilibrium Reservoir and Fluid Characterization with Downhole Fluid Analysis 17 Optical density (color) TrueVrticaldepth,ft) EoS model for two zones Measured
  18. 18. XX15 Sand Multiwell Oil Column Pressures and Fluids A 2-D representation is getting complex, not easy to understand !18
  19. 19. 3-D Representation of WFT analysis: India • Start in 3D • Line of section • WS Window • 3D Showing OD distribution 19
  20. 20. Pressures Sampling and Downhole Fluid Analysis (DFA) Transient Testing In-Situ Stress Testing Reservoir Characterization 20
  21. 21. DeltaP Saturn Probe h= 12.2 m Kh =640 mD Kv= 125 mD μ =370 cp DeltaP Observation Probe Rate History Pressure Match Conventional WFT Transient Testing: Mexico 21
  22. 22.  Can use existing inlet devices (Dual packers, 3D Radial Probe)  High power downhole pump (up to 71 bbl/day)  Slip joint for pipe expansions  Drill-pipe conveyed, can circulate mud while pumping Hydrocarbon Mixture Drilling Mud ReservoirQuad-Packer High Capacity Downhole Pump Circulating Equipment Slip Joint 3DRadialProbe QuadPacker DualPacker New – WFT Deep Transient Testing 22
  23. 23. Cores Logs FT pretests WFT Transient Tests Well Testing Radius of investigation WFT Deep Transient Testing Understanding the reservoir deeper 23
  24. 24. Flow Regime Identification and model match: Norwegian sea Three buildups; 11 Darcy permeability. Flow rate was 71 rb/d  Total station time 26 hr, with 6 hr flow period.  Radius of investigation was 576m. 24
  25. 25. Multiphase Transport Properties from Petrophysics and WFT • WFT sampling operation provides bottom-hole pressure and water- cut data • Multi-depth resistivity logs provide invasion profile (electromagnetic- EM modeling) • A numerical model determines multiphase flow properties in an inversion workflow 25
  26. 26. Field Example: WFT pressure and water cut match Match of measured pressures and water-cut. Inverted capillary pressure and relative permeabilities 26
  27. 27. Field Example: Near wellbore saturation images Oil saturation is from 0.15 (blue) to 0.70 (red) End of dynamic filtration at 0.5 day Laterolog logging at 2.0 days Beginning of WFT cleanup at 6.6 days End of WFT cleanup at 6.7 days End of pressure buildup at 6.7 days 27
  28. 28. Pressures Sampling and Downhole Fluid Analysis Transient Testing (IPTT) In-Situ Stress Testing Reservoir Characterization 28
  29. 29. Pore Pressure and Fracture Gradient Established workflow in the industry to define a safe drilling window for well construction (circa 1970s) Questions always arise …  Impact of faults?  Tectonic stresses?  Rock properties?  Calibration techniques? 1 Equivalent Mud Weight (g/cc or PPG) 3 TVD Overburden Stress Fracture Gradient “Leak off” tests Pore pressure calibration Mud Weight Pore Pressure 29
  30. 30. Industry Advancements: 3D Geomechanical Models  Detailed integrated geology and reservoir modeling  Highly precise calculations  Still requires well control and calibration 30
  31. 31. Fracture initiation Closure pressure Breakdown pressure The micro-hydraulic fracturing with WFT packers + images 31
  32. 32. What we desire in Next Generation Wireline Formation Testers?  Easy/tailor-made survey design and conduct  Ultra-pure samples in much shorter time in every environment  Deep transient testing  Conveyance independent deployment  Real time fluid modeling  Early reservoir insights Lessons learned from ~20 years of pumpout WFT’s 32
  33. 33. Concluding Remarks Reservoir and Fluid Characterization with Formation Testers: Reducing Asset Uncertainties Pressure, fluid analysis, transient test results and stress tests are seamlessly getting integrated into RE software and workflows Advanced downhole sensors will be included New Generation tools are emerging with more capabilities Transient testing capabilities are improved, reducing risks in reservoir evaluation 33
  34. 34. Society of Petroleum Engineers Distinguished Lecturer Program www.spe.org/dl 34 Your Feedback is Important Enter your section in the DL Evaluation Contest by completing the evaluation form for this presentation Visit SPE.org/dl 34

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