1. CPGE Surfactant-Based Enhanced Oil recovery Processes and Foam Mobility Control Task 4: Simulation of Field-Scale Processes Center for Petroleum and Geosystems Engineering The University of Texas at Austin Austin, Texas June 4, 2005 Mojdeh Delshad Gary Pope Glen Anderson Hourshad Mohammadi Nariman Fathi

2. CPGE Objectives Design and optimize a surfactant flood for Midland Farm oil reservoir Study the effect of wettability on the performance of surfactant flood Literature survey on effect of wettability on petrophysical properties Develop and implement a procedure to model wettability alteration

3. CPGE Base Case Midland Farms Simulation Matching Water Injection Rate - Permeability Field - Relative Permeability Curves - Waterflood Injection Rate Design Parameters Base Case Results - Production Rates - Cumulative Oil Recovery - Production History - Oil Saturation Profiles - Surfactant Concentration Profiles - Residual Oil Saturation Profiles Sensitivity Analysis

4. CPGE Permeability Field Stochastic Permeability Field V dp =0.75 x = y = 20 ft z = 4 ft

5. CPGE Relative Permeability Curves Corey Type Parameters

6. CPGE Water Injection Rate and Phase Cut during Waterflood

7. CPGE Design Parameters

8. CPGE

10. Chemical Flood Production Rates (1 PV Polymer Drive)

11. CPGE Chemical Flood Oil Recovery (1 PV Polymer Drive)

12. CPGE Produced Phase Cuts during Chemical Flood (1 PV Polymer Drive)

13. CPGE Produced Chemical Concentrations (1 PV Polymer Drive)

14. CPGE Oil Saturation During Chemical Flooding 0.2 PV 0.75 PV 1.25 PV

15. CPGE Surfactant Concentration 0.2 PV0.75 PV 1.25 PV

16. CPGE Reservoir and Fluid Properties LxWxH660x660x30 ft Grid Blocks11x11x5 Depth to Pay4700 ft Initial Pressure1975 psi Reservoir Temperature103 o F Average Permeability80 md Porosity0.16 Water Compressibility3x10 -6 psi -1 Oil Compressibility1x10 -5 psi -1 Water Density62.43 lb/ft 3 Oil Density54.33 lb/ft 3 Water Viscosity0.7 cp Oil Viscosity5 cp Water/Oil IFT20 dynes/cm Constant Injection Rate250 bbl/day Constant Production Pressure300 psi

17. CPGE Effect of Wettability on S or

18. CPGE CDC for Berea Sandstone (Amaefule 1982)

19. CPGE CDC in Berea Sandstone (Mohanty 1983)

20. CPGE CDC in Carbonates (Kamath 2001)

21. CPGE Permeability Distribution md

22. CPGE Effect of Wettability on Relative Permeability

23. CPGE Effect of Wettability on Capillary Pressure

24. CPGE Effect of Wettability on Waterflood Recovery

25. CPGE Effect of Wettability on Chemical Oil Recovery

26. CPGE Effect of Wettability on Reservoir Pressure

27. CPGE Effect of Wettability on Oil Production Rate

28. CPGE Oil Saturation during Waterflood (Waterwet Case) 0.2 PV 0.9 PV

29. CPGE Oil Saturation during Waterflood (Mixedwet Case) 1.0 PV 3.5 PV

30. CPGE Oil Saturation during Waterflood (Oilwet Case) 0.3 PV 1.9 PV

31. CPGE Oil Saturation during Surfactant Flood (Waterwet Case) 0.25 PV 0.75 PV 2.25 PV

32. CPGE Oil Saturation during Surfactant Flood (Mixedwet Case) 0.25 PV 0.75 PV 2.25 PV

33. CPGE Oil Saturation during Surfactant Flood (Oilwet Case) 0.25 PV 0.75 PV 2.25 PV

34. CPGE Surfactant concentration at 0.75 PV Waterwet Mixedwet Oilwet

35. CPGE Final Oil Saturation Waterwet Mixedwet Oilwet

36. CPGE Wettability Alteration  Wettability Index vs. surfactant properties  Residual saturation  Relative Permeability  Capillary pressure  Capillary desaturation

37. CPGE Model 1: Wettability Effect Only  Read the table of water and relative permeabilities vs. water saturation for the in-situ wettability i.e mixed-wet  Read the table of water-oil capillary pressure vs. water saturation for the in-situ wettability  Read another set of tables for the altered wettability i.e water-wet  Check the gridblock value of surfactant concentration at each time step  Switch the tables if the surfactant concentration is above an input tolerance

38. CPGE Model 2: Effect of Wettability and Mobilization  Relative permeability curves for oil and water at two extreme wettability conditions  Capillary pressure curves for two extreme strongly water-wet and strongly oil-wet  Capillary desaturation curves for each phase at the two extreme conditions of wettability

39. CPGE Model 2 - Linear Interpolation Strongly water-Wet  Relative permeability at low IFT  Capillary desaturation curves  Relative permeability at high IFT Strongly Oil-Wet  Relative permeability at low IFT  Capillary desaturation curves  Relative permeability at high IFT

40. CPGE Relative Permeability Curves (Morrow 1973)

41. CPGE High NC Relative Permeability  Calculate relative permeability endpoints  Calculate relative permeability exponent

42. CPGE Model 2 - Linear Interpolation F = constant Or Or Develop new relationship based on lab. data

43. CPGE Model 3: Under Development! Determine the Wettability Index in each gridblock and each time step based on surfactant property Compute residual saturations as a function of Wettability Index

44. CPGE Sor vs Wettability Correlation

45. CPGE Sor vs. Wettability Index for Berea Core

46. CPGE Normalized Residual Oil Saturation vs. Wettability Index (All Data)

47. CPGE Wettability and CDC Indiana Limestone (Abrams) Berea Sandstone (Gupta) Capillary Number

48. CPGE Trapping Number vs Wettability Index Correlation

49. CPGE Computation Procedure Establish relative permeability, capillary pressure, and capillary desaturation curves for initial and altered wettability conditions Determine the change in Wettability Index (I W ) in the presence of surfactant Develop a correlation between residual saturation and I W Develop a correlation between trapping number and I W Compute high capillary number relative permeability for altered wettability