FRACTURING FLUID WATER REUSE SYSTEM AND METHOD

• US 20120024525A1
• Filed: 07/28/2011
• Published: 02/02/2012
• Est. Priority Date: 07/28/2010
• Status: Active Grant

• Current Assignee: Chevron USA Incorporated (Chevron Corp.)
• Original Assignee: Chevron USA Incorporated (Chevron Corp.)
• Inventors: Svarczkopf, Timothy C., Weaver, Dalton R. III, Bender, Jon M., Strickler, Jesse J.
• Granted Patent: US 9,027,646 B2
• Time in Patent Office: Days
• US Class Current: 166/267
• CPC Class Codes: C09K 8/62 Compositions for forming crevices or fractures
• CPC Class Codes: C09K 8/72 Eroding chemicals, e.g. acids

Abstract

Methods of processing a fluid recovered from an oil or gas extraction operation for reuse in a hydraulic fracturing fluid are described. The methods include providing an amount of a produced fluid composition containing iron and suspended solids and controlling at least one of the conductivity, iron content, oxidative strength, and pH of the composition, such that Fenton'"'"'s reagent is formed in situ. Also described are hydraulic fracturing fluids produced using fluid recovered from an oil or gas production process and treated in accordance with the methods described herein as well as systems for preparing a hydraulic fracturing fluid having, as a fluid source, fluid recovered from an oil or gas production process that has been treated in accordance with the methods described herein.

Claims

1. A method of processing fluid recovered from an oil or gas extraction operation for reuse in a hydraulic fracturing fluid, comprising:

providing an amount of a produced fluid composition containing iron and suspended solids; and

controlling at least one of the conductivity, iron content, oxidative strength, and pH of the composition, such that Fenton'"'"'s reagent is formed in situ.

2. The method of claim 1, wherein reaction of the Fenton'"'"'s reagent causes formation of complexes of iron and the suspended solids.

3. The method of claim 2, wherein formation of the complexes causes coagulation and flocculation of the suspended solids.

4. The method of claim 1, wherein the conductivity of the composition is at least 10,000 μ

mhos/cm.

5. The method of claim 1, wherein the conductivity of the composition is controlled through the addition of production brine having a conductivity of at least 150,000 μ

mhos/cm.

6. The method of claim 1, wherein the iron content of the composition is at least 5 ppm.

7. The method of claim 1, wherein the iron content is controlled through the addition of an iron salt to the composition.

8. The method of claim 1, wherein the oxidative strength of the composition is controlled by one or more of the following:

addition of hydrogen peroxide, addition of peracetic acid, and aeration of the composition.

9. The method of claim 1, wherein the pH of the composition is between 5.0 and 6.5.

10. The method of claim 1, wherein the suspended solids comprise one or more of kerogen, asphaltenes, and acrylamide solids.

11. The method of claim 1, further comprising adding to the composition a friction reducer.

12. The method of claim 11, wherein the friction reducer is at least one of an acrylic-acid-AMPS-polyacrylamide terpolymer, a brine dispersion AMPS-polyacrylamide copolymer, and a non-ionic polyacrylamide polymer.

13. The method of claim 1, further comprising adding to the composition a scale inhibitor.

14. The method of claim 13, wherein the scale inhibitor is a sulphonated phosphinocarboxylic acid copolymer.

15. The method of claim 1, further comprising adding to the composition an iron dispersant.

16. The method of claim 15, wherein the iron dispersant is a sulphonated, carboxylated, non-ionic terpolymer.

17. The method of claim 1, further comprising mixing the composition at a rate and frequency sufficient to prevent the occurrence of density-based striation.

18. The method of claim 11, wherein, prior to being added to the composition, the friction reducer is pre-treated in an aqueous solution to increase the hydration thereof.

25. A hydraulic fracturing fluid, comprising fluid recovered from an oil or gas extraction operation treated in accordance with the method of claim 1.

26. The hydraulic fracturing fluid of claim 25, wherein the fluid recovered from an oil or gas extraction operation comprises flow back water and production brine.

27. The hydraulic fracturing fluid of claim 25, further comprising one or more of a friction reducer, an iron dispersant, and a scale inhibitor.

28. The hydraulic fracturing fluid of claim 27, further comprising a friction reducer, wherein the friction reducer is at least one of an acrylic-acid-AMPS-polyacrylamide terpolymer, a brine dispersion AMPS-polyacrylamide copolymer, and a non-ionic polyacrylamide polymer.

30. A system for preparing a hydraulic fracturing fluid, comprising, in series for fluid flow therebetween:

a fluid source, comprising fluid recovered from an oil or gas extraction operation that has been treated in accordance with the method of claim 1;

a friction reducer inlet for supplying a friction reducer; and

a mixing apparatus.

31. The system of claim 30, further comprising a friction reducer holding tank for pre-treating the friction reducer in an aqueous solution.

32. The system of claim 30, further comprising an in-line conductivity analyzer between the fluid source and the mixing apparatus.

33. The system of claim 32, wherein data from the conductivity analyzer is provided to a feedback control system for adjusting the amount and type of friction reducer added to the hydraulic fracturing fluid.

35. The method of hydraulic fracturing of claim 34, wherein the hydraulic fracturing fluid comprises fluid recovered from an oil or gas extraction operation treated in accordance with the method of claim 1.

19. A method of reusing a produced fluid in a hydraulic fracturing operation, the method comprising:

receiving the produced fluid from a well as a return of at least a hydraulic fracturing fluid in a hydraulic fracturing operation;

providing a production brine recovered from an oil or gas extraction operation, the production brine having a conductivity of at least 150,000 μ

mhos/cm;

measuring a conductivity of the produced fluid;

treating the produced fluid by adding thereto at least the production brine to form a treated produced fluid in which Fenton'"'"'s reagent forms in situ, wherein the treating of the produced fluid comprises;

increasing the conductivity of the produced fluid to at least 10,000 μ

mhos/cm;

increasing an iron content of the produced fluid to at least 5 ppm; and

increasing an oxidation-reduction potential value of the produced fluid to at least 250 mV;

storing the treated produced fluid for a sufficient time to allow flocculation of suspended solids in the treated produced fluid, thereby forming a clarified produced fluid from which the suspended solids have been removed; and

injecting the clarified produced fluid into a well as part of a hydraulic fracturing fluid.

20. The method according to claim 19, wherein the treating step comprises increasing the conductivity of the produced fluid to at least 150,000 μ

mhos/cm and increasing the iron content of the produced fluid to at least 50 ppm.

21. The method according to claim 19, wherein the treating step further comprises adding an acid to the produced fluid to adjust the pH level of the produced fluid to between about 5.0 and about 6.5.

22. The method according to claim 19, further comprising adding a friction reducer to the clarified produced fluid, the friction reducer being mixed with at least one of the clarified produced fluid or an aqueous solution for unwinding at least one hour before the step of injecting the clarified produced fluid into the well.

23. The method according to claim 22, further comprising, prior to injecting the hydraulic fracturing fluid into the well, injecting an acid composition comprising an acid and a friction reducer into the well.

24. The method according to claim 19, further comprising mixing the clarified produced fluid at a rate and frequency sufficient to prevent the occurrence of density-based striation.

29. A hydraulic fracturing fluid, comprising fluid recovered from an oil or gas extraction operation treated in accordance with the method of claim 19.

34. A method of hydraulic fracturing, comprising:

pre-treating a well by injecting an acid composition comprising an acid and a friction reducer into a well bore; and

injecting a hydraulic fracturing fluid into the well bore.