Oil recovery processing using a low salinity fluid composition

Patent metadata

Field	Value
Publication number	US-10041339-B2
Application number	US-201314377073-A
Country	US
Kind code	B2
Filing date	Feb 8, 2013
Priority date	Feb 9, 2012
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

Method of recovering oil from a subterranean oil-bearing reservoir by using an injection fluid containing a viscosifying polymer in a low salinity water. The low salinity water has a total dissolved solids (TDS) content of 15,000 ppmv or less, and the ratio of the multivalent cation content of the low salinity water to the multivalent cation content of the connate water of the reservoir is less than 1. The viscosity of the injection fluid is in the range of 3 to 200 cP, and the reservoir is penetrated by one or more injection wells and by one or more production wells. The method includes injecting the injection fluid into at least one of the injection wells in a slug size in the range of 0.4 to 1.5 pore volume (PV).

First claim

The invention claimed is:

1. A method of recovering oil from a subterranean oil-bearing reservoir using an injection fluid comprising a viscosifying polymer in a low salinity water, the method comprising:
determining a viscosity of the injection within the reservoir based on at least one of a composition of the viscosifying polymer, a molecular weight of the viscosifying polymer, a concentration of the viscosifying polymer, a composition of the low salinity water, a temperature of the reservoir, or a shear rate of the injection fluid within the reservoir;
wherein the reservoir is penetrated by one or more injection wells and by one or more production wells, and wherein the reservoir contains oil having a viscosity of from 40 to 200 cP;
preparing the injection fluid, wherein the injection fluid comprises the viscosifying polymer in the low salinity water, wherein the low salinity water has a total dissolved solids (TDS)content of 15,000 ppmv or less, wherein the ratio of the multivalent cation content of the low salinity water to the multivalent cation content of the connate water of the reservoir is less than 1;
wherein the determined viscosity of the injection fluid within the reservoir is matched to the viscosity of the oil under reservoir conditions such that a ratio of a mobility of the injection fluid to a mobility of the oil in the reservoir is less than one,
initiating injection of the injection fluid into at least one of the injection wells, wherein the injection fluid is injected in a slug size in the range of 0.5 to 0.9 pore volumes (PV); and
sweeping oil in the reservoir towards at least one of the one or more production wells based on the initiation of the injection of the injection fluid into the at least one of the injection wells.

2. The method according to claim 1 , wherein the injection fluid is injected in a slug size of from 0.6 to 0.8 PV.

3. The method according to claim 1 or claim 2 , wherein the low salinity water has a TDS content of less than 12,000 ppmv.

4. The method according to claim 1 or claim 2 , wherein the low salinity water has a total dissolved solids (TDS) content of at least 100 ppmv.

5. The method according claim 1 or claim 2 , wherein the ratio of the multivalent cation content of the low salinity water to the multivalent cation content of the connate water of the reservoir is less than 0.9.

6. The method according to claim 1 or claim 2 , wherein the low salinity water that is employed as the base fluid of the injection fluid has a multivalent cation content of less than 200 ppmv.

7. The method according to claim 1 or claim 2 , wherein the viscosifying polymer is an acrylamide polymer.

8. The method according to claim 1 or claim 2 , wherein the injection fluid is a solution of the viscosifying polymer in the low salinity water.

9. The method according to claim 1 or claim 2 , wherein the injection fluid is a dispersion of the viscosifying polymer in the low salinity water.

10. The method as claimed in claim 1 or claim 2 wherein injection fluid comprises at least 500 ppm of the polymer by weight.

11. The method according to claim 1 or claim 2 , wherein the mobility of the oil to the in situ mobility of the injection fluid is close to or at 1:1.

12. The method according to claim 1 or claim 2 , wherein after injection of the injection fluid, a drive fluid may be injected into the reservoir.

13. The method according to claim 1 or claim 2 , wherein a spacer fluid is injected into the reservoir before and/or after injection of the injection fluid.

14. The method as claimed in claim 12 , wherein the drive fluid is injected into the reservoir in a greater pore volume than the injection fluid.

15. The method as claimed in claim 14 , wherein the drive fluid is injected into the reservoir in a pore volume of at least 1.

16. The method as claimed in claim 1 or claim 2 , wherein the injection fluid is injected under pressure into at least one injection well that is spaced from a production well, and passes directly into the oil-bearing rock of the reservoir from the injection well.

17. The method as claimed in claim 12 wherein the injection fluid is injected at a pressure 10,000 to 100,000 kPa (100 to 1000 bar).

18. The method as claimed in claim 1 or claim 2 , wherein after injection of the injection fluid, a drive fluid may be injected into the reservoir, which drive fluid sweeps the injection fluid through the reservoir to the production well.

19. The method as claimed in claim 18 , wherein the drive fluid is injected into the reservoir in a greater pore volume than the injection fluid.

20. The method as claimed in claim 19 , wherein the drive fluid is injected into the reservoir in a pore volume of at least 1.

21. The method according to claim 1 or 2 , wherein the injection fluid is injected during secondary recovery.

22. The method according to claim 21 , wherein the low salinity water has a TDS content of less than 12,000 ppmv.

23. The method according to claim 21 , wherein the low salinity water has a total dissolved solids (TDS) content of at least 100 ppmv.

24. The method according to claim 21 , wherein the ratio of the multivalent cation content of the low salinity water to the multivalent cation content of the connate water of the reservoir is less than 0.9.

25. The method according to claim 21 , wherein the low salinity water that is employed as the base fluid of the injection fluid has a multivalent cation content of less than 200 ppmv.

26. The method according to claim 21 , wherein the viscosifying polymer is an acrvlamide polymer.

27. The method as claimed in claim 21 wherein the injection fluid comprises at least 500ppm of the polymer by weight.

28. The method according to claim 21 , wherein the mobility of the oil to the in situ mobility of the injection fluid is close to or at 1: 1.

29. The method according to claim 21 , wherein after injection of the injection fluid, a drive fluid may be injected into the reservoir.

30. The method as claimed in claim 21 , wherein after injection of the injection fluid, a drive fluid may be injected into the reservoir, which drive fluid sweeps the injection fluid through the reservoir to the production well.

31. The method as claimed in claim 30 , wherein the drive fluid is injected into the reservoir in a greater pore volume than the injection fluid.

32. The method as claimed in claim 31 , wherein the drive fluid is injected into the reservoir in a pore volume of at least 1.

33. The method as claimed in claim 29 , wherein the drive fluid is injected into the reservoir in a greater pore volume than the injection fluid.

34. The method as claimed in claim 33 , wherein the drive fluid is injected into the reservoir in a pore volume of at least 1.

35. A method of recovering oil from a subterranean oil-bearing reservoir using an injection fluid, the method comprising;
determining a viscosity of the injection fluid within the reservoir based on at least one of a composition of the vicosifying polymer, a molecular weight of the vicosifying polymer, a concentration of the vicosifying polymer, a composition of the low salinity water, a temperature of the reservoir, or a shear rate of the injection fluid within the reservoir;

Assignees

• Bp Exploration Operating Co Ltd

Inventors

• Jerauld Gary Russell
• Mohammadi Hourshad

Classifications

• C09K8/588 Primary

  characterised by the use of specific polymers {(polymeric surfactants C09K8/584)} · CPC title

• E21B43/16

  Enhanced recovery methods for obtaining hydrocarbons · CPC title

• C09K8/58

  Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids · CPC title

• E21B43/20 Primary

  Displacing by water · CPC title