Method and system for management of by-products from subterranean zones

• US 6,681,855 B2
• Filed: 10/19/2001
• Issued: 01/27/2004
• Est. Priority Date: 10/19/2001
• Status: Expired due to Fees

• Current Assignee: Effective Exploration LLC
• Original Assignee: CDX Gas LLC (EnerVest Ltd.)
• Inventors: Rial, Monty H., Zupanick, Joseph A.
• Primary Examiner(s): Bagnell, David
• Assistant Examiner(s): KRECK, JOHN J
• Application Number:
  US10/046,001
• Publication Number:
  US 20030075322A1
• Time in Patent Office: 830 Days
• Field of Search: 166/245, 166/268, 166/263, 166/305.1, 166/306
• US Class Current: 166/268
• CPC Class Codes: E21B 43/00 Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells applicable only to water E03B
• CPC Class Codes: E21B 43/006 Production of coal-bed methane E21B43/243 takes precedence
• CPC Class Codes: E21B 43/305 comprising at least one inclined or horizontal well

Abstract

An improved method for management of by-products from subterranean zones, comprising drilling a first well system into a subterranean zone, wherein the first well system comprises a first drainage pattern. By-product and gas from a first volume of the subterranean zone is removed via the first well system. A second well system is drilled into the subterranean zone, wherein the second well system comprises a second drainage pattern, and by-product is moved from a second volume of the subterranean zone to the first volume of the subterranean zone. Gas is then produced from the second volume of the subterranean zone. Subsequent drainage patterns repeat the process.

Claims

1. A method for management of subterranean by-product, comprising:

drilling a first well system into a subterranean zone, wherein the first well system comprises a first drainage pattern;

removing via the first well system by-product from a first volume of the subterranean zone;

producing gas from the first volume of the subterranean zone;

drilling a second well system into the subterranean zone, wherein the second well system comprises a second drainage pattern;

forming a subsurface hydraulic connection between the first drainage pattern and the second drainage pattern;

moving by-product from a second volume of the subterranean zone to the first volume of the subterranean zone; and

producing gas from the second volume of the subterranean zone.

2. The method of claim 1, wherein the subterranean zone has an initial formation pressure below 250 pounds per square inch (psi).

3. The method of claim 1, wherein the subterranean zone has an initial formation pressure below 150 pounds per square inch (psi).

4. The method of claim 1, wherein at least one of the drainage patterns comprises a main bore with a plurality of lateral bores.

5. The method of claim 1, wherein at least one of the drainage patterns provides substantially uniform fluid flow within a subterranean area.

6. The method of claim 1, wherein at least one of the drainage patterns comprises a main bore extending from a first end of an area in the subterranean zone to a distant end of the area, and at least one set of lateral bores extending outwardly from a side of the main bore.

7. The method of claim 6, wherein the lateral well bores progressively shorten as a distance between a respective lateral well bore and the first end increases.

8. The method of claim 1, wherein the subterranean zone comprises a coal seam, the by-product comprises water, and the gas comprises coalbed methane.

9. The method of claim 1, wherein the second well system is substantially updip of the first well system.

10. The method of claim 1, wherein a majority of the by-product feasibly removable from the second volume is moved from the second volume of the subterranean zone to the first volume of the subterranean zone.

11. The method of claim 1, wherein the moving by-product from a second volume of the subterranean zone to the first volume of the subterranean zone is by pumping the by-product from the second volume to the surface followed by re-injecting the by-product into the first volume.

12. The method of claim 11, wherein the pumping is via a pump, an inlet of which is disposed in an enlarged cavity formed in a well-bore and the pump operable to pump fluid accumulated in the enlarged cavity to the surface.

13. A method for management of subterranean by-product, comprising:

drilling a first well system into a subterranean zone, the subterranean zone having a structural dip, wherein the first well system comprises a first substantially dip-parallel drainage pattern extending updip in the subterranean zone and ending at a first terminus;

removing via the first well system by-product from a first volume of the subterranean zone to allow gas production from the first volume;

producing gas from the first volume via the first well system;

drilling a second well system into the subterranean zone, wherein the second well system comprises a second substantially dip-parallel drainage pattern extending updip in the subterranean zone and updip of the first terminus and ending at a second terminus; and

moving via the first well system and the second well system by-product from a second volume of the subterranean zone to the first volume of the subterranean zone; and

producing gas from the second volume of the subterranean zone via the second well system.

14. The method of claim 13, wherein the moving comprises removing to the surface the fluid from the second volume and causing the fluid to flow from the surface to the first volume of the subterranean zone.

15. The method of claim 14, wherein the flow from the surface to the first volume of the subterranean zone is via the first well system.

16. The method of claim 13, wherein the moving comprises forming a hydraulic connection between the first substantially dip-parallel drainage pattern and the second substantially dip-parallel drainage pattern.

17. The method of claim 13, wherein the hydraulic connection is subsurface.

18. The method of claim 17, further comprising:

drilling a third well system into the subterranean zone, wherein the third well system comprises a third substantially dip-parallel drainage pattern extending updip in the subterranean zone and updip from the second terminus; and

moving by-product from a third volume of the subterranean zone to at least one of the first and second volume of the subterranean zone.

19. The method of claim 18, wherein the moving comprises removing to the surface the fluid from the third volume of the subterranean zone and causing the fluid to flow from the surface to at least one of the first and second volume of the subterranean zone.

20. The method of claim 19, wherein the flow from the surface to at least one of the first and second volume of the subterranean zones is via the first or second well system.

21. The method of claim 18, wherein the moving comprises forming a hydraulic connection between the first substantially dip-parallel drainage pattern and the second substantially dip-parallel drainage pattern.

22. The method of claim 21, wherein the hydraulic connection is subsurface.

23. The method of claim 13, wherein at least one of the substantially dip-parallel drainage patterns comprises a main bore with a plurality of lateral bores.

24. The method of claim 13, wherein at least one of the substantially dip-parallel drainage patterns provides substantially uniform fluid flow within a subterranean area.

25. The method of claim 13, wherein at least one of the substantially dip-parallel drainage patterns comprises a main bore extending from a first end of an area in the subterranean zone to a distant end of the area, and at least one set of lateral bores extending outwardly from a side of the main bore.

26. The method of claim 13, wherein the subterranean zone comprises a coal seam, the by-product comprises water, and the gas comprises coalbed methane.

27. The method of claim 13, wherein the drainage patterns each comprise an area of about 150-200 acres.

28. The method of claim 13, wherein at least 80% of the gas in the first and second volumes of the subterranean zone is produced and wherein substantially all of the by-product from the second volume of the subterranean zone is moved back into the subterranean zone.