Acid Treating Subterranean formations (Patent No: 831808)

Inventor: Bombardieri, Caurino C.

Location: Calgary

Comments: N/A

Description: The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for improving the permeability of a subterranean carbonate formation surrounding a well which comprises injecting a solution of a surface active agent having anionic functional groups into said formation, injecting a hydrocarbon oil into said formation behind said solution, closing in the well for a period of from about 1 to about 24 hours, and thereafter injecting an acid into the formation behind said hydrocarbon oil.

2. A method as defined by claim 1 wherein said surface active agent is a mixture of anionic and cationic compounds.

3. A method as defined by claim 1 wherein said surface active agent is a mixture of anionic and nonionic compounds.

4. A method as defined by claim 1 wherein said solution contains said surface active agent in a concentration of from about 20 to about 80 percent by weight.

5. A method as defined by claim 1 wherein said acid is an aqueous acid solution including a surface active agent.

6. A method as defined by claim 1 wherein a fluid miscible with both oil and water is injected into said formation prior to the injection of said solution of a surface active agent.

7. A method as defined by claim 1 wherein a hydrocarbon oil is injected into said formation prior to the injection of said solution of a surface active agent.

8. A method as defined by claim 1 wherein from about 1 to about 5 barrels of said solution of a surface active agent is injected into said formation for each 1000 gallons of said acid that is injected.

9. A method as defined by claim 1 wherein from about 10 to about 40 barrels of said hydrocarbon oil is injected into said formation for each 1000 gallons of said acid that is injected.

10. A method as defined by claim 1 wherein said acid comprises chloroacetic acid.

11. A method as defined by claim 1 wherein said well is closed in for a period of from about 3 to about 8 hours.

12. A method as defined by claim 1 wherein an acid is injected into said well prior to the injection of said solution of a surface active agent.

13. A method for treating a subterranean carbonate formation surrounding a well which comprises injecting a fluid miscible with oil and water into said formation, injecting a hydrocarbon oil to displace said fluid from around said well, introducing a solution of an anionic surface active agent into said formation behind said oil, injecting additional hydrocarbon oil into said formation, shutting in said well for a period of several hours, injecting an acid solution into said formation, again shutting in said well for several hours, and thereafter producing fluids from said formation.

14. A method as defined by claim 13 wherein said fluid miscible with oil and water is isopropyl alcohol.

15. A method as defined by claim 13 wherein said solution containing said surface active agent is an alcohol-water solution containing from about 20 to about 50 weight percent of an oil-soluble, water-dispersible anionic sulfonate.