FRACTURE CLEAN-UP BY ELECTRO-OSMOSIS

• US 20110278012A1
• Filed: 10/24/2008
• Published: 11/17/2011
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Marino, Sonia, Thiercelin, Marc
• Granted Patent: US 9,745,841 B2
• Time in Patent Office: Days
• US Class Current: 166/311
• CPC Class Codes: C09K 2208/08 Fiber-containing well treatment fluids
• CPC Class Codes: C09K 2208/26 Gel breakers other than bacteria or enzymes
• CPC Class Codes: C09K 8/52 Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
• CPC Class Codes: C09K 8/68 containing organic compounds
• CPC Class Codes: C09K 8/80 Compositions for reinforcing fractures, e.g. compositions of proppants used to keep the fractures open
• CPC Class Codes: C09K 8/805 Coated proppants
• CPC Class Codes: E21B 43/26 by forming crevices or fractures
• CPC Class Codes: E21B 43/267 reinforcing fractures by propping

Abstract

A method is given for improving the clean-up of fracture fluid from a fracture by assisting Darcy flow by electro-osmotic effects. Proppants having suitable surface potential, and fracture fluids having suitable electrical conductivity are chosen. Then a suitable electric field is imposed, using electrodes placed on the surface or in adjacent wells. The current creates an electro-osmotic flow that carries fluid to the wellbore.

Claims

1. A method for promoting clean-up of fracture fluid from a fracture in a subterranean formation penetrated by a wellbore after a fracturing treatment, the method comprising creating an electrically conductive proppant pack, fracturing with an electrically conductive fracture fluid, placing at least one electrode in electric communication with the fracture, and subjecting the fracture to an electric field.

2. The method of claim 1 wherein the proppant comprises sand.

3. The method of claim 1 wherein the proppant is a ceramic coated with a coating that makes the proppant electrically conductive.

4. The method of claim 3 wherein the coating comprises a metal.

5. The method of claim 3 wherein the coating comprises an electrically conductive resin.

6. The method of claim 1 wherein the surface potential of the proppant is at least as negative as about −

50 mV.

7. The method of claim 1 wherein the proppant pack further comprises electrically conductive fibers.

8. The method of claim 7 wherein the fibers dissolve during clean-up.

9. The method of claim 1 wherein the proppant pack further comprises metallic particles.

10. The method of claim 1 wherein the proppant pack comprises proppant particles that are not electrically conductive.

11. The method of claim 10 wherein the proppant pack comprises conductive and non-conductive particles of differing densities.

12. The method of claim 1 wherein the conductivity of the proppant pack is varied along the length of the fracture.

13. The method of claim 1 wherein the fracture fluid comprises a breaker.

14. The method of claim 1 wherein the pH of the fluid is between about 7 and about 11.

15. The method of claim 1 wherein injection of the fracture fluid is preceded by injection of a pad fluid having a higher electrical conductivity than the fracture fluid.

16. The method of claim 1 wherein the fracture fluid has a lower electrical conductivity than the formation fluid.

17. The method of claim 1 wherein the conductivity of the fracture fluid is varied along the length of the fracture.

18. The method of claim 1 further wherein a hydraulic pressure gradient is created.

19. The method of claim 1 wherein the fracture has two wings and at least one electrode is placed in electric communication with each wing.

20. The method of claim 19 wherein at least one electrode is the casing of another wellbore.

21. The method of claim 1 wherein the electric field is initiated at the start of clean-up.

22. The method of claim 1 wherein the electric field is initiated after the start of clean-up.

23. The method of claim 1 wherein the electric field is applied intermittently.

24. The method of claim 1 wherein the electric field in the fracture is above about 0.05 V/m.

25. The method of claim 1 wherein the electric field in the fracture is between about 0.05 V/m and about 10 V/m.

26. The method of claim 1 wherein the proppant pack further contains a component that decreases the permeability of the pack.

27. The method of claim 1 wherein the proppant pack further contains a component that increases the surface area of the pack.

28. A method comprising creating an electrically conductive proppant pack, fracturing with an electrically conductive fracture fluid, and placing at least one electrode in electric communication with the fracture, wherein the proppant is a material coated with a coating that makes the proppant electrically conductive.

29. A method comprising creating an electrically conductive proppant pack, fracturing with an electrically conductive fracture fluid, and placing at least one electrode in electric communication with the fracture, wherein the proppant pack comprises proppant particles that are not electrically conductive.