Fracturing fluids and methods for treating hydrocarbon-bearing formations

Patent metadata

Field	Value
Publication number	US-9688904-B2
Application number	US-201213718844-A
Country	US
Kind code	B2
Filing date	Dec 18, 2012
Priority date	Jun 29, 2012
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

Disclosed herein is a fracturing fluid comprising a carrier fluid; a polymer that is soluble in the carrier fluid; the polymer being a synthetic polymer, wherein the synthetic polymer comprises a labile group that is operative to facilitate decomposition of the synthetic polymer upon activation of the labile group; the synthetic polymer being operative to increase the viscosity of the carrier fluid to about 5 to about 50 centipoise; the fracturing fluid being operative to reduce friction during a downhole fracturing operation and to transport a proppant during the downhole fracturing operation; and an oxidizing agent. A method for treating a hydrocarbon-bearing formation is also disclosed herein.

First claim

What is claimed is:

1. A method for treating a hydrocarbon-bearing formation comprising:
blending a carrier fluid with a synthetic polymer and an oxidizing agent to form a fracturing fluid, the synthetic polymer being a polyacrylamide further comprising a labile group or a polyacrylate further comprising a labile group, the labile group comprising ester groups, carbonate groups, azo groups, disulfide groups, orthoester groups, acetal groups, etherester groups, ether groups, silyl groups, phosphazine groups, urethane groups, etheramide groups, anhydride groups, or a combination thereof; the oxidizing agent and the labile group being selected such that the oxidizing agent is effective to activate the labile group and the activated labile group facilitates the decomposition of the synthetic polymer;
injecting the fracturing fluid into the hydrocarbon-bearing formation, the fracturing fluid having a viscosity of about 5 to about 50 centipoise during injection;
discharging the fracturing fluid into a downhole fracture in the hydrocarbon-bearing formation, wherein the fracturing fluid is operative to reduce friction during a hydrocarbon-bearing treatment operation;
activating the labile group on the synthetic polymer with the oxidizing agent;
decomposing the synthetic polymer upon activation of the labile group to provide a decomposed polymer; and
removing the decomposed polymer from the hydrocarbon-bearing formation,
wherein the synthetic polymer is devoid of guar.

2. The method of claim 1 , further comprising adding a reducing agent to the fracturing fluid.

3. The method of claim 2 , wherein the reducing agent is sodium erythorbate, iron sulfate, oxalic acid, formic acid, ascorbic acid, erythorbic acid, a compound comprising a metal ion wherein the metal ion is a copper ion, an iron ion, a tin ion, a manganese ion or a sulfur ion, or a combination comprising at least one of the foregoing.

4. The method of claim 2 , wherein the weight ratio of the oxidizing agent to the reducing agent is about 0.1:1 to about 100:1.

5. The method of claim 2 , wherein the oxidizing agent is present in an amount from about 0.001 wt % to about 0.5 wt %, based on the total weight of the fracturing fluid, and the reducing agent is present in an amount from about 0.0006 wt % to about 0.12 wt %, based on the total weight of the fracturing fluid.

6. The method of claim 2 , wherein the oxidizing agent is present in an amount of about 0.02 wt. % to about 0.12 wt. %, the reducing agent is present in an amount of about 0.002 wt. % to about 0.012 wt. %, each based on the total weight of the fracturing fluid; and the weight ratio of the oxidizing agent to the reducing agent is about 1:1 to about 20:1.

7. The method of claim 2 , wherein the reducing agent is iron sulfate.

8. The method of claim 1 , further comprising adding a crosslinking agent to the fracturing fluid.

9. The method of claim 1 , wherein the oxidizing agent is an earth metal alkali oxidizing compound, a bromate oxidizing compound, or a combination comprising at least one of the foregoing.

10. The method of claim 1 , wherein the synthetic polymer is the polyacrylamide further comprising the labile group.

11. The method of claim 1 , wherein upon activation of the labile group, the viscosity of the fracturing fluid is reduced to 2 centipoise or less.

12. The method of claim 1 , wherein the fracturing fluid is free of a crosslinking agent.

13. The method of claim 1 , wherein the fracturing fluid is free of a naturally occurring polymer.

14. The method of claim 1 , wherein the synthetic polymer has a number average molecular weight of about 2,000,000 to about 20,000,000 grams per mole.

15. The method of claim 1 , wherein the synthetic polymer is present in an amount of about 0.1 wt % to about 10 wt %, based on the total weight of the fracturing fluid.

16. The method of claim 1 , wherein the fracturing fluid further comprises a clay control agent or a breaker catalyst.

17. The method of claim 1 , wherein the oxidizing agent is sodium bromate, potassium bromate, or a combination comprising at least one of the foregoing.

18. The method of claim 1 , wherein the fracturing fluid further comprises acetyl triethyl citrate.

19. The method of claim 18 , wherein the acetyl triethyl citrate is included in the fracturing fluid in an amount of from about 0.0011 wt % to about 1.1 wt %, based on the total weight of the fracturing fluid.

20. A method for treating a hydrocarbon-bearing formation comprising:
blending a carrier fluid with a synthetic polymer, an oxidizing agent, and a reducing agent to form a fracturing fluid, the synthetic polymer being a polyacrylamide copolymer further comprising a labile group or a polyacrylate copolymer further comprising a labile group, the labile group comprising ester groups, amide groups, carbonate groups, azo groups, disulfide groups, orthoester groups, acetal groups, etherester groups, ether groups, silyl groups, phosphazine groups, urethane groups, etheramide groups, anhydride groups, or a combination thereof; the oxidizing agent and the labile group being selected such that the oxidizing agent is effective to activate the labile group and the activated labile group facilitates the decomposition of the synthetic polymer;
injecting the fracturing fluid into the hydrocarbon-bearing formation, the fracturing fluid having a viscosity of about 5 to about 50 centipoise during injection;
discharging the fracturing fluid into a downhole fracture in the hydrocarbon-bearing formation, wherein the fracturing fluid is operative to reduce friction during a hydrocarbon-bearing treatment operation;
activating the labile group on the synthetic polymer with the oxidizing agent; wherein upon activation of the labile group, the viscosity of the fracturing fluid is reduced to 2 centipoise or less;
decomposing the synthetic polymer upon activation of the labile group to provide a decomposed polymer; and
removing the decomposed polymer from the hydrocarbon-bearing formation,
wherein the synthetic polymer is present in an amount of about 0.1 wt. % to about 10 wt. %, the oxidizing agent is present in an amount of about 0.02 wt. % to about 0.12 wt. %, and the reducing agent is present in an amount of about 0.002 wt. % to about 0.012 wt. %, each based on the total weight of the fracturing fluid; and the weight ratio of the oxidizing agent to the reducing agent is about 4:1 to about 12:1.

21. The method of claim 20 , wherein the carrier fluid is slickwater.

22. The method of claim 20 , wherein the fracturing fluid further comprises acetyl triethyl citrate in an amount of from about 0.011 wt % to about 0.55 wt %, based on the total weight of the fracturing fluid.

23. The method of claim 20 , wherein the fracturing fluid reaches its maximum viscosity within 10 to 40 seconds after introduction of the synthetic polymer into the carrier fluid.

Assignees

• Wang Xiaolan
• Qu Qi
• Nelson Scott
• Sun Hong
• Guerin Michael
• Baker Hughes Inc

Inventors

• Wang Xiaolan
• Qu Qi
• Nelson Scott
• Sun Hong
• Guerin Michael

Classifications

• C09K8/685 Primary

  containing cross-linking agents · CPC title

• C09K8/62 Primary

  Compositions for forming crevices or fractures · CPC title