Method of treating subterranean gas hydrate formations

• US 6,148,911 A
• Filed: 03/30/1999
• Issued: 11/21/2000
• Est. Priority Date: 03/30/1999
• Status: Expired due to Term

• Current Assignee: Atlantic Richfield Company (BP PLC)
• Original Assignee: Atlantic Richfield Company (BP PLC)
• Inventors: Gipson, Larry P., Montgomery, Carl T.
• Primary Examiner(s): TSAY, FRANK
• Application Number:
  US09/281,088
• Time in Patent Office: 602 Days
• Field of Search: 166/248, 166/272.2, 166/272.1, 166/271, 166/263, 166/276, 166/279, 166/308
• US Class Current: 166/248
• 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 41/0099 specially adapted for drilling for or production of natural hydrate or clathrate gas reservoirs; Drilling through or monitoring of formations containing gas hydrates or clathrates
• CPC Class Codes: E21B 43/2401 by means of electricity
• CPC Class Codes: E21B 43/2405 in association with fracturing or crevice forming processes E21B43/247 takes precedence
• CPC Class Codes: E21B 43/267 reinforcing fractures by propping

Abstract

A gas hydrate formation is treated by horizontally fracturing the formation, placing electrically conductive proppant particles in the fracture, and passing an electric current through the proppant particles in the fracture to generate sufficient heat to release gas from the hydrate. The method has particular application in shallow gas-bearing formations underlying or within the permafrost.

Claims

1. A method of treating a subterranean gas hydrate formation penetrated by a wellbore, which comprises

(a) fracturing the subterranean gas hydrate formation to form a substantially horizontal fracture therein;

(b) placing electrically conductive proppant particles in the fracture;

(c) permitting the fracture to close on the proppant particles;

(d) passing an electric current from the surface through the wellbore and through the proppant particles to heat the formation in the immediate vicinity of the proppant particles to cause at least some gas to be released from the hydrate; and

(e) producing the released gas through the fracture and up the wellbore.

2. The method of claim 1 wherein the electrically conductive proppant particles comprise particles which are at least partially coated with a heat hardenable conductive resin and wherein the electric current passed through the proppant particles causes the conductive resin to harden, thereby aggregating at least some of the particles together.

3. The method of claim 2 wherein the particles which are coated are non-conductive.

4. The method of claim 3 wherein the particles are of a material selected from the group consisting of ceramics, glass, sands, inorganic oxides, organic resins and polymers and combinations thereof.

5. The method of claim 2 wherein the particles are substantially completely coated with the heat hardenable, electrically-conductive resin.

6. The method of claim 5 wherein the resin is present in an amount sufficient to consolidate the particles but insufficient to fill openings between the particles.

7. The method of claim 1 wherein the particles are of a material selected from the group consisting of conductive metals, conductive metal alloys, conductive metal oxides, conductive metal salts, and combinations thereof.

8. The method of claim 1 wherein the particles are aluminum pellets.

9. The method of claim 1 wherein the particles have an average particle size from about 60 to about 8 Tyler mesh.

10. The method of claim 9 wherein the conductive resin comprises a phenol formaldehyde resin containing graphite which is heat hardenable at temperatures above about 135°

F.

11. The method of claim 10 wherein the conductive resin is present in an amount equal to from about 0.5 to about 6.0 weight percent based upon the weight of the proppant.

12. The method of claim 1 wherein the initial formation temperature is less than about 135°

F.

13. The method of claim 1 wherein at least substantial portions of gas hydrate formation underlies or penetrates a permafrost region.

14. The method of claim 13 wherein the hydrate formation is from 300 feet to 2500 feet below the surface.