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. (Christensen et al., 1998) SPE 39833
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. One- and Two-Phase
Configurations
Water
Oil
Gas

7. Three-Phase
Configurations
Water
Oil
Gas

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

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

10. Mobilising Oil by Double Displacement
Water
Oil
Gas
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 Water Injection
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. Hydrocarbon Trapping (Jerauld, 1996) SPE 36178
weakly wat-wet
water wet

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 Shell Schlumberger Statoil BHP BG Saudi Aramco Eni
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