Method for treating subterranean formations

Patent metadata

Field	Value
Publication number	US-10202535-B2
Application number	US-201515507579-A
Country	US
Kind code	B2
Filing date	Aug 6, 2015
Priority date	Aug 28, 2014
Publication date	Feb 12, 2019
Grant date	Feb 12, 2019

Abstract

Method of treating a portion of a subterranean formation comprising the injection of an aqueous fluid containing a modified polysaccharide bearing ethylenically unsaturated double bonds and an initiator of radical polymerization.

First claim

The invention claimed is:

1. A method for treating a portion of a subterranean formation comprising:
i. providing an aqueous fluid comprising:
a) from 0.05 to 3.0% by weight of a modified polysaccharide, the modified polysaccharide being a polysaccharide bearing ethylenically unsaturated double bonds, with the double bonds having a degree of substitution (DSDB) of from 0.0001 to 0.5,
wherein the modified polysaccharide is formed by reaction with an unsaturated acyl halide, or anhydride, or ester, or acid, or silane, or epoxide bearing an ethylenically unsaturated double bond;
b) from 0 to 3.0% by weight of a polyethylenically unsaturated compound different from the modified polysaccharide a);
c) from 0.0001% to 1% by weight of a radical polymerization initiator chosen from the group consisting of photoinitiators, thermal free radical initiators, redox free radical initiators, and combinations thereof;

ii. introducing the aqueous fluid into a portion of a subterranean formation by pumping or injecting the fluid at a pressure sufficient to fracture the subterranean formation; and
iii. before or after having introduced the aqueous fluid into a portion of a subterranean formation, inducing thickening of the aqueous fluid by exposing the fluid to UV-visible light irradiation or to heat.

2. The method of claim 1 wherein the modified polysaccharide a) is selected from the group consisting of a modified polygalactomannan, a modified polygalactomannan derivative, and a modified cellulose ether.

3. The method of claim 2 wherein the modified polysaccharide a) is a modified polygalactomannan.

4. The method of claim 3 wherein the modified polygalactomannan is a modified guar.

5. The method of claim 4 wherein the modified guar is a guar (meth)acrylate.

6. The method of claim 1 wherein the modified polysaccharide is carboxymethyl cellulose.

7. The method of claim 1 wherein the polyethylenically unsaturated compound is methylenebisacrylamide.

8. The method of claim 1 wherein the radical polymerization initiator is a photoinitiator and the thickening of the aqueous fluid is induced by exposing the fluid to UV-visible light irradiation.

9. The method of claim 1 wherein the radical polymerization initiator is a thermal or redox radical initiator and the thickening of the aqueous fluid is induced by exposing the fluid to heat.

10. The method of claim 1 , wherein the aqueous fluid is an aqueous fracturing fluid.

11. The method of claim 1 wherein the modified polysaccharide has a DSDB of from 0.001 to 0.03.

12. The method of claim 1 wherein the modified polysaccharide has a DSDB of from 0.01 to 0.03.

13. The method of claim 1 wherein the inducing of the thickening of the aqueous fluid is performed by irradiating the fluid with UV-visible light.

14. The method of claim 1 wherein from about 0.01 to about 1 wt % of the polyethylenically unsaturated compound is contained in the aqueous fluid.

15. The method of claim 14 wherein from about 0.05 to about 0.5 wt % of the polyethylenically unsaturated compound is contained in the aqueous fluid.

16. The method of claim 1 wherein the aqueous fluid has a pH equal to or less than 8.

17. The method of claim 16 wherein the aqueous fluid has a pH equal to or less than 7.

18. The method of claim 1 wherein the aqueous fluid is prepared using produced oilfield water.

19. The method of claim 1 wherein the radical polymerization initiator is a free radical initiator selected from the group consisting of sodium sulfite, sodium bisulfite, sodium metabisulfite and combinations thereof.

20. The method of claim 1 wherein the radical polymerization initiator is a water soluble thermal azo-initiator selected from the group consisting of: 4,4′-azobis(4-cyanopentanoic acid), 2,2′-azobis(2-methylpropionamidine)dihydrochloride (V-50), 2,2′-azobisisobutyronitrile (AIBN) and combinations thereof.

Assignees

• Lamberti Spa

Inventors

• Cavo Enrico
• Giardini Lorenzo
• Casiraghi Angelo
• Merli Luigi
• Tenconi Mauro
• Pirovano Pierangelo
• Floridi Giovanni
• Li Bassi Giuseppe
• Macchi Roberto

Classifications

• C09K8/685

  containing cross-linking agents · CPC title

• C09K8/90

  of natural origin, e.g. polysaccharides, cellulose · CPC title

• C09K8/428 Primary

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

• C09K8/20

  Natural organic compounds or derivatives thereof, e.g. polysaccharides or lignin derivatives · CPC title

• C09K8/512

  containing cross-linking agents · CPC title