METHOD OF TREATING SUBTERRANEAN FORMATIONS BY IN-SITU HYDROLYSIS OF ORGANIC ACID ESTERS

• US 20090131285A1
• Filed: 11/14/2008
• Published: 05/21/2009
• Est. Priority Date: 11/16/2007
• Status: Abandoned Application

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Joel L. Boles, Qi Qu, Xiaolan Wang
• Inventors: Qu, Qi, Wang, Xiaolan, Boles, Joel L.
• Application Number:
  US12/271,667
• Publication Number:
  US 20090131285A1
• Time in Patent Office: Days
• US Class Current: 507/252
• CPC Class Codes: C09K 8/72 Eroding chemicals, e.g. acids

Abstract

An oil or gas well penetrating a subterranean formation, such as a carbonate formation, is treated with a well treatment fluid which contains an organic ester. The fluid may be an oil-in-water emulsion of the organic ester and an emulsifier or a homogeneous solution of organic ester and a water/mutual solvent solution. Acid is produced in-situ by hydrolysis of the organic ester.

Claims

1. A method of treating an oil or gas well penetrating a formation which comprises:

(a) introducing into the oil or gas well a well treatment fluid comprising an organic ester; and

(b) hydrolyzing the organic ester in-situ to produce acid wherein the well treatment fluid is either (i) an oil-in-water emulsion of an emulsifier and the organic ester;

or (ii) a homogeneous solution of organic ester and a water/mutual solvent solution.

2. The method of claim 1, wherein the well treatment fluid introduced into the oil or gas well in step (a) is an emulsion of an emulsifier and the organic ester.

3. The method of claim 2, wherein the organic ester is an ester of an organic sulfonic acid.

4. The method of claim 3, wherein the ester of an organic sulfonic acid is selected from the group consisting of methyl p-toluenesulfonate, ethyl p-toluenesulfonate, methyl methanesulfonate and ethyl methanesulfonate.

5. The method of claim 1, wherein the oil or gas well is treated in the absence of a diverting agent.

6. The method of claim 1, wherein the emulsifier is non-ionic.

7. The method of claim 1, wherein the well is shut-in prior to hydrolysis of the organic ester.

8. The method of claim 1, wherein the well treatment fluid is a homogeneous solution of organic ester and a water/mutual solvent solution.

9. The method of claim 8, wherein the mutual solvent of the water/mutual solvent solution is selected from the group consisting of glycols, glycol ethers, terpenes, and C₃ to C₉ alcohols.

10. The method of claim 9, wherein the glycol is ethylene glycol monobutyl ether.

11. A method of matrix acidizing a carbonate subterranean formation penetrated by an oil or gas well which comprises:

(a) injecting into the well a well treatment fluid comprising an organic acid ester; and

(b) hydrolyzing the organic ester in-situ to produce acid

(c) increasing the permeability of the carbonate subterranean formation wherein the well treatment fluid is either (i) an oil-in-water emulsion of an emulsifier and the organic ester;

or (ii) a homogeneous solution of organic ester and a water/mutual solvent solution.

12. The method of claim 11, wherein the well treatment fluid injected into the well in step (a) is an emulsion of an emulsifier and the organic ester.

13. The method of claim 12, wherein the organic ester is an ester of an organic sulfonic acid.

14. The method of claim 13, wherein the ester of an organic sulfonic acid is selected from the group consisting of methyl p-toluenesulfonate, ethyl p-toluenesulfonate, methyl methanesulfonate and ethyl methanesulfonate.

15. The method of claim 11, wherein the well is shut-in prior to hydrolysis of the organic ester.

16. The method of claim 11, wherein the well treatment fluid is a homogeneous solution of organic ester and a water/mutual solvent solution.

17. The method of claim 16, wherein the mutual solvent of the water/mutual solvent solution is selected from the group consisting of glycols, glycol ethers, terpenes, and C₃ to C₉ alcohols.

18. A method of matrix acidizing a carbonate formation penetrated by an oil or gas well which comprises:

(a) injecting into the well a well treatment fluid selected from the group consisting of;

(i) an oil-in-water emulsion comprising an organic acid ester and a surfactant;

or

(ii) a homogeneous solution of organic acid ester in a water/mutual solvent solution;

(b) shutting-in the well;

(c) producing acid in-situ by hydrolyzing the organic acid ester; and

(d) increasing the permeability of the carbonate formation wherein the organic acid ester is selected from the group consisting of methyl p-toluenesulfonate, ethyl p-toluenesulfonate, methyl methanesulfonate and ethyl methanesulfonate.

19. The method of claim 18, wherein the depth of the oil or gas well is at least 15,000 feet below the surface of the earth.

20. The method of claim 18, wherein the well treatment fluid is an oil-in-water emulsion and further wherein the amount of organic acid ester in the emulsion is less than or equal to 10 volume percent.