Methods for servicing subterranean wells

Patent metadata

Field	Value
Publication number	US-9950952-B2
Application number	US-201213603367-A
Country	US
Kind code	B2
Filing date	Sep 4, 2012
Priority date	Nov 30, 2010
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

Pumpable process-fluid compositions and methods for establishing hydraulic isolation in cemented subterranean wells comprise more than 1 wt % polyacrylamide and a non-metallic crosslinker. Upon entering voids and cracks in or adjacent to a cement sheath, and contacting the set-cement surfaces, the compositions react and form a seal that prevents further leakage.

First claim

The invention claimed is:

1. A method for repairing a cemented wellbore penetrating a subterranean formation, comprising:
i. preparing an aqueous process fluid composition comprising more than 1 wt % polyacrylamide and a non-metallic crosslinker, and having an initial pH between about 3 and about 9;
ii. pumping the process fluid composition down the wellbore and into cracks in, or voids adjacent to a set cement sheath, thereby causing calcium hydroxide to diffuse from the set cement sheath into the process fluid composition, and the polyacrylamide therein to crosslink and form a set product; and
iii. forming a seal.

2. The method of claim 1 , wherein the non-metallic crosslinker comprises a polylactam.

3. The method of claim 1 , wherein the non-metallic crosslinker comprises polyvinylpyrrolidone, polyvinylcaprolactam or a combination thereof.

4. The method of claim 3 , wherein the polyvinylpyrrolidone has a weight average molecular weight of greater than or equal to about 50,000 g/mol and less than or equal to about 2 million g/mol.

5. The method of claim 1 , wherein the non-metallic crosslinker has a weight average molecular weight greater than or equal to about 10,000 g/mol and less than or equal to about 2 million g/mol.

6. The method of claim 1 , wherein the polyacrylamide has a degree of hydrolysis higher than or equal to about 0% and lower than or equal to about 40%.

7. The method of claim 1 , wherein the molecular weight of the polyacrylamide is between about 10,000 g/mol and 20 million g/mol.

8. The method of claim 1 , wherein the initial pH of the composition is between about 3 and about 9.

9. The method of claim 1 , wherein the composition further comprises a pH-adjusting agent.

10. The method of claim 1 , wherein the wellbore has been cemented with Portland cement, a lime/silica blend, a lime/pozzolan blend, calcium aluminate cementor a combination thereof.

11. A method for restoring zonal isolation in a cemented wellbore penetrating a subterranean formation, comprising:
i. preparing an aqueous process fluid composition comprising more than 1 wt % polyacrylamide and a non-metallic crosslinker, and having an initial pH between about 3 and about 9;
ii. pumping the process fluid composition down the wellbore and into cracks in, or voids adjacent to a set cement sheath, thereby causing calcium hydroxide to diffuse from the set cement sheath into the process fluid composition, and the polyacrylamide therein to crosslink and form a set product; and
iii. forming a seal.

12. The method of claim 11 , wherein the non-metallic crosslinker comprises a polylactam.

13. The method of claim 11 , wherein the non-metallic crosslinker comprises polyvinylpyrrolidone, polyvinylcaprolactam or a combination thereof.

14. The method of claim 13 , wherein the polyvinylpyrrolidone has a weight average molecular weight of greater than or equal to about 50,000 g/mol and less than or equal to about 2 million g/mol.

15. The method of claim 11 , wherein the non-metallic crosslinker has a weight average molecular weight greater than or equal to about 10,000 g/mol and less than or equal to about 2 million g/mol.

16. The method of claim 11 , wherein the polyacrylamide has a degree of hydrolysis higher than or equal to about 0% and lower than or equal to about 40%.

17. The method of claim 11 , wherein the molecular weight of the polyacrylamide is between about 10,000 g/mol and 20 million g/mol.

18. The method of claim 11 , wherein the initial pH of the composition is between about 3 and about 9.

19. The method of claim 11 , wherein the composition further comprises a pH-adjusting agent.

20. The method of claim 11 , wherein the wellbore has been cemented with Portland cement, a lime/silica blend, a lime/pozzolan blend, calcium aluminate cementor a combination thereof.

Assignees

• Lin Lijun
• Sullivan Philip F
• Tustin Gary John
• Schlumberger Technology Corp

Inventors

• Lin Lijun
• Sullivan Philip F
• Tustin Gary John

Classifications

• E21B33/13

  Methods or devices for cementing, for plugging holes, crevices or the like · CPC title

• C04B28/02

  containing hydraulic cements other than calcium sulfates · CPC title

• C04B7/00 Primary

  Hydraulic cements (calcium sulfate cements C04B11/00) · CPC title

• C09K8/467

  containing additives for specific purposes · CPC title

• C09K8/428

  for squeeze cementing, e.g. for repairing · CPC title