ENHANCED OIL RECOVERY IN LOW PERMEABILITY RESERVOIRS

• US 20120125644A1
• Filed: 11/24/2010
• Published: 05/24/2012
• Est. Priority Date: 11/24/2010
• Status: Active Grant

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: ZHOU, Dengen
• Granted Patent: US 9,033,047 B2
• Time in Patent Office: Days
• US Class Current: 166/403
• CPC Class Codes: C09K 8/594 Compositions used in combination with injected gas , e.g. CO2 orcarbonated gasC09K8/592 takes precedence
• CPC Class Codes: E21B 43/164 Injecting CO2 or carbonated water in combination with organic material C09K8/594
• CPC Class Codes: E21B 43/166 Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium CO2 injection E21B43/164; steam injection E21B43/24
• CPC Class Codes: Y02P 90/70 Combining sequestration of CO2 and exploitation of hydrocarbons by injecting CO2 or carbonated water in oil wells

Abstract

A method for enhancing hydrocarbon recovery in low permeability reservoirs comprises first providing a subterranean reservoir comprising one or more hydrocarbons and water therewithin and a wellbore in fluid communication with the subterranean reservoir. Next, a substantially anhydrous composition is injected into the reservoir through the wellbore. The substantially anhydrous composition comprises carbon dioxide and one or more surfactants. The composition is suitable to form a foam upon contact with the water within the reservoir. The method often results in reduced wellbore corrosion and hydrate formation, reduced reservoir fingering, and enhanced carbon dioxide sweep efficiency over conventional methods.

Claims

1. A method for enhancing hydrocarbon recovery in low permeability reservoirs, the method comprising:

(a) providing a subterranean reservoir comprising one or more hydrocarbons and water therewithin;

(b) providing a wellbore in fluid communication with the subterranean reservoir;

(c) injecting carbon dioxide into the subterranean reservoir through the wellbore; and

(d) injecting a substantially anhydrous composition into the subterranean reservoir through the wellbore, the substantially anhydrous composition comprising the carbon dioxide and one or more surfactants and being suitable to form a foam upon contact with water within the subterranean reservoir.

2. The method of claim 1, wherein about 1% to about 2% hydrocarbon pore volumes of the carbon dioxide are injected in step (c).

3. The method of claim 1, wherein the carbon dioxide comprises less than about 150 parts per million of water.

4. The method of claim 1, wherein the subterranean reservoir is offshore.

5. The method of claim 1, wherein the subterranean reservoir has a depth of at least about 10,000 feet.

6. The method of claim 1, wherein the subterranean reservoir has a bottom-hole injection pressure of at least about 15,000 psig.

7. The method of claim 1, wherein the subterranean reservoir has a permeability of less than about 10 millidarcy.

8. The method of claim 1, wherein the subterranean reservoir has a permeability of less than about 5 millidarcy.

9. The method of claim 1, wherein the one or more surfactants of the substantially anhydrous composition are sufficiently soluble in the carbon dioxide such that the carbon dioxide and the one or more surfactants do not significantly separate in the wellbore.

10. The method of claim 1, wherein the method further comprises recovering hydrocarbons from the subterranean reservoir through a production well.

11. The method of claim 1, wherein the carbon dioxide and the one or more surfactants are injected into the wellbore simultaneously.

12. The method of claim 1, wherein the carbon dioxide and the one or more surfactants are injected into the wellbore consecutively.

13. The method of claim 1, wherein the carbon dioxide is injected into the wellbore continuously and the one or more surfactants are injected intermittently.

14. The method of claim 1, wherein the total amount of the one or more surfactants in the substantially anhydrous composition is from about 0.01 to about 0.5 percent by weight based on the total weight of the substantially anhydrous composition.

15. The method of claim 1, wherein the total amount of the one or more surfactants in the substantially anhydrous composition is from about 0.01 to about 0.3 percent by weight based on the total weight of the substantially anhydrous composition,

16. A method for enhancing hydrocarbon recovery in low permeability reservoirs, the method comprising:

(a) providing a subterranean reservoir comprising one or more hydrocarbons and water therewithin;

(b) providing a wellbore in fluid communication with the subterranean reservoir;

(c) providing dehydrated carbon dioxide;

(d) injecting the dehydrated carbon dioxide into the subterranean reservoir through the wellbore; and

(e) adding one or more surfactants to the dehydrated carbon dioxide after a predetermined amount of dehydrated carbon dioxide has been injected in step (d).

17. The method of claim 16, wherein adding the one or more surfactants to the dehydrated carbon dioxide in step (e) forms a substantially anhydrous composition that is suitable to form a foam upon contact with water within the subterranean reservoir.

18. The method of claim 16, wherein:

adding the one or more surfactants to the dehydrated carbon dioxide in step (e) forms a substantially anhydrous composition; and

the total amount of the one or more surfactants in the substantially anhydrous composition is from about 0.01 to about 0.5 percent by weight based on the total weight of the substantially anhydrous composition.

19. The method of claim 16, wherein the dehydrated carbon dioxide comprises less than about 150 parts per million of water.

20. The method of claim 16, wherein the predetermined amount of dehydrated carbon dioxide in step (e) comprises about 1% to about 2% hydrocarbon pore volumes.