Pore-Scale Analysis of WAG & Development of a New Empirical Model

1. Pore-Scale Analysis of WAG & Development of a New Empirical Model Centre for Petroleum Studies Department of Earth Science and Engineering Imperial College London Vural Sander Suicmez Dr. Mohammad Piri Prof. Martin J. Blunt 20 January 2006

2. Motivation • Pore Network Modelling (Fatt, 1956). • Wide range of 3-phase flow scenarios. • Improvement in computational power. • A physically motivated three-phase relative permeability model (Blunt, 2000).

3. Outline • Introduction to WAG • What has already been done? (Piri and Blunt, 2005) • Two- and three-phase pore-scale fluid configurations • Displacement mechanisms • New work on Cyclic Injection (WAG) • New displacement mechanisms • Validating the model • Effects of Wettability • A New Relative Permeability Model • Isoperm Curves & Effect of Displacement Path • Oil & Gas Trapping • Conclusions

4. What is the problem? (Christensen et al., 1998)SPE 39833

5. What do we have? Piri, 2004 • A three-phase flow simulator (incorporating geologically realistic network model) with full extension of possible generic configurations for any wettability. • A robust clustering algorithm incorporating coalescence and break of trapped clusters. • Point-by-point comparison with data using saturation path tracking algorithm.

6. Water Oil Gas One- and Two-Phase Configurations

7. Water Oil Gas Three-Phase Configurations

8. * Connectivity and Clustering (Hoshen & Kopelman, 1976) Dead End Outlet Inlet Cluster is Connected Periodic Boundary Condition

9. Gas Configuration B Configuration A Configuration B Water Oil Configuration F Configuration A Configuration C Example Displacement Sequence Primary Drainage Water Flooding Gas Injection Layer Collapsing Gas Injection

10. Water Oil Gas Mobilising Oil by Double Displacement Trapped Oil

11. Multiple Displacements (Van Dijke & Sorbie, 2003) For a better connected network, double displacements are sufficient

12. Double Displacements • Gas Injection Gas Oil Water Gas Water Oil • Water Injection Water Oil Gas Water Gas Oil • Oil Injection Oil Gas Water Oil Water Gas

13. Model Validation (Oak, 1990) Water2 Gas1 Water1

14. Gas Relative Permeability

15. Oil Reconnection

16. Water Relative Permeabilty

17. Pore Occupancy

18. Oil/Water Capillary Pressure

19. Model Validation(Egermann et al, 2000) • Spreading Oil Layers • Water-Wet

20. Model Validation(Egermann et al, 2000) Water Gas

21. Gas Relative Permeability

22. Water Relative Permeability

23. Generic WAG Study (Strongly Oil-Wet) • Spreading Oil Layers • Strongly Oil-Wet

24. Generic WAG Study (Strongly Oil-Wet) Gas1 Gas2 Water1 Water2

25. Oil Relative Permeability

26. Gas Relative Permeability

27. Pore Occupancies

28. Krw Comparison

29. Kro Comparison

30. Oil Isoperm (Spiteri & Juanes, 2004) SPE 89921 Stone I Stone II

31. Oil Isoperm Water-wet Oil-wet

32. Displacement Path Water-gas Water-gas-water

33. water wet weakly wat-wet Hydrocarbon Trapping (Jerauld, 1996) SPE 36178

34. Hydrocarbon Trapping

35. Conclusions • Double displacement mechanism plays an important role in a water-wet system. • Impact of WAG cycles on oil recovery lessened in an oil-wet medium. • Gas behaviour is complex, depends whether it is the most non-wetting phase or not. • Rel perms for different displacement paths are similar as a function of flowing saturation. • Further work on oil and gas trapping is necessary.

36. Acknowledgments We are thankful to the members of the Imperial College Consortium on Pore-Scale Network Modelling; • Shell • Schlumberger • Statoil • BHP • BG • Saudi Aramco • Eni • Total • Japan Oil, Gas and Metals National Corp. (JOGMEC) • Department of Trade and Industry (DTI) • EPSRC