Recyclable cleanout fluids

• US 9,328,282 B2
• Filed: 06/22/2012
• Issued: 05/03/2016
• Est. Priority Date: 06/29/2011
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Li, Leiming
• Primary Examiner(s): Bates, Zakiya W
• Application Number:
  US13/530,295
• Publication Number:
  US 20130000916A1
• Time in Patent Office: 1,411 Days
• US Class Current: 1/1
• CPC Class Codes: C09K 8/32 Non-aqueous well-drilling compositions, e.g. oil-based
• CPC Class Codes: C09K 8/52 Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
• CPC Class Codes: E21B 21/065 Separating solids from drilling fluids
• CPC Class Codes: E21B 37/06 using chemical means for preventing or limiting , e.g. eliminating, the deposition of paraffins or like substances

Abstract

A method for treating a wellbore or a subterranean formation penetrated by a wellbore includes preparing a gelled oil at the surface, introducing the gelled oil into the wellbore, recovering the gelled oil at the surface, adding a base to the gelled oil to reduce the viscosity, allowing entrained solids to settle out, adding an acid to increase the viscosity, and re-injecting the gelled oil.

Claims

1. A method of treating a subterranean formation penetrated by a wellbore comprising:

preparing a gelled oil at the surface,

performing a first cycle comprising injecting the gelled oil into a well through coiled tubing, recovering the gelled oil at the surface, reducing the viscosity of the recovered oil by adding a first pH-adjusting agent, treating the resulting fluid having reduced viscosity, increasing the viscosity of the treated fluid by adding a second pH-adjusting agent to reestablish the gel, and

starting a second cycle by re-injecting the gelled oil into the well through coiled tubing.

2. The method of claim 1 wherein the gelled oil comprises a hydrocarbon mixture, a gelling agent, and a crosslinking agent.

3. The method of claim 1 wherein the treatment is wellbore cleanout.

4. The method of claim 1 wherein the treatment is drilling.

5. The method of claim 1 wherein the step of treating the resulting

fluid having reduced viscosity comprises removing solids from the resulting

fluid having reduced viscosity.

6. The method of claim 1 wherein the first pH-adjusting agent comprises a base.

7. The method of claim 1 wherein the second pH-adjusting agent comprises an acid.

8. The method of claim 1 wherein the gelled oil comprises (a) diesel, (b) a phosphate ester and (c) a ferrous compound, a ferric compound or an aluminum compound.

9. The method of claim 1 wherein the step of increasing the viscosity of the treated fluid comprises adding a gelling agent, a crosslinking agent, or both.

10. A method of cleaning out a wellbore penetrating a subterranean formation, said method comprising:

injecting through coiled tubing a gelled oil into the wellbore,

entraining a solid from the wellbore,

recovering the gelled oil at the surface,

removing the solid from the gelled oil by adding a first pH-adjusting agent to reduce the viscosity of the resulting fluid relative to the gelled oil,

increasing the viscosity of the resulting fluid by adding a second pH-adjusting agent to reestablish the gel, and re-injecting the gelled oil into the well through coiled tubing.

11. The method of claim 10 wherein the gelled oil comprises a hydrocarbon mixture, a gelling agent, and a crosslinking agent.

12. The method of claim 10 wherein the first pH-adjusting agent comprises a base.

13. The method of claim 10 wherein the second pH-adjusting agent comprises an acid.

14. The method of claim 10 wherein the gelled oil comprises (a) diesel, (b) a phosphate ester and (c) a ferrous compound, a ferric compound or an aluminum compound.

15. The method of claim 10 wherein the step of increasing the viscosity of the resulting fluid comprises adding a gelling agent, a crosslinking agent, or both.