Method and system for accessing subterranean deposits from the surface

• US 6,561,288 B2
• Filed: 06/20/2001
• Issued: 05/13/2003
• Est. Priority Date: 11/20/1998
• Status: Expired due to Term

• Current Assignee: Effective Exploration LLC
• Original Assignee: CDX Gas LLC (EnerVest Ltd.)
• Inventors: Zupanick, Joseph A.
• Primary Examiner(s): Shackelford, Heather
• Assistant Examiner(s): KRECK, JOHN J
• Application Number:
  US09/885,219
• Publication Number:
  US 20020134546A1
• Time in Patent Office: 692 Days
• Field of Search: 175/61, 175/62, 175/65, 175/69, 166/245, 166/50, 166/52
• US Class Current: 175/69
• CPC Class Codes: E21B 43/006 Production of coal-bed methane E21B43/243 takes precedence
• CPC Class Codes: E21B 43/13 specially adapted to dewatering of wells of gas producing reservoirs, e.g. methane producing coal beds
• CPC Class Codes: E21B 43/305 comprising at least one inclined or horizontal well
• CPC Class Codes: E21B 47/09 Locating or determining the position of objects in boreholes or wells , e.g. the position of an extending arm; Identifying the free or blocked portions of pipes
• CPC Class Codes: E21B 7/046 horizontal drilling drilling with mechanical conveying means E21B7/003
• CPC Class Codes: E21F 7/00 Methods or devices for drawing- off gases with or without subsequent use of the gas for any purpose

Abstract

Improved method and system for accessing subterranean deposits from the surface that substantially eliminates or reduces the disadvantages and problems associated with previous systems and methods. In particular, the present invention provides an articulated well with a drainage pattern that intersects a horizontal cavity well. The drainage patterns provide access to a large subterranean area from the surface while the vertical cavity well allows entrained water, hydrocarbons, and other deposits to be efficiently removed and/or produced.

Claims

1. A method for accessing a subterranean zone from the surface, comprising:

drilling a substantially vertical well bore from the surface to the subterranean zone;

drilling an articulated well bore from the surface to the subterranean zone, the articulated well bore horizontally offset from the substantially vertical well bore at the surface and intersecting the substantially vertical well bore at a junction proximate to the subterranean zone; and

drilling through the articulated well bore into the subterranean zone extending from the junction a main well bore and a plurality of lateral well bores extending from the main well bore.

2. The method of claim 1, further comprising:

forming an enlarged cavity in the substantially vertical well bore proximate to the subterranean zone;

drilling the articulated well bore to intersect the large cavity of the substantially vertical well bore; and

drilling through the articulated well bore the main well bore from the enlarged cavity into the subterranean zone.

3. The method of claim 1, wherein the subterranean zone comprises a coal seam.

4. The method claim 1, wherein the subterranean zone comprises an oil reservoir.

5. The method of claim 1, further comprising producing fluid from the subterranean zone through the substantially vertical well bore.

6. The method of claim 1, further comprising:

installing a substantially vertical rod pumping unit into the substantially vertical well bore with a pump inlet proximate to the junction; and

operating the substantially vertical rod pumping unit to produce fluid from the subterranean zone.

7. The method of claim 1, wherein the subterranean zone comprises a low-pressure zone.

8. The method of claim 1, wherein drilling the main well bore from the junction into the subterranean zone comprises drilling a substantially horizontal diagonal well bore from the junction defining a first end of an area in the subterranean zone to a distant end of the area, and wherein drilling the plurality of lateral well bores comprises:

drilling a first set of substantially horizontal lateral well bores in space relation to each other from the diagonal well bore to the periphery of the area on a first side of the diagonal well bore; and

drilling a second set of substantially horizontal lateral well bores in space relation to each other from the diagonal well bore to the periphery of the area on a second, opposite side of the diagonal well bore.

9. The method of claim 8, wherein each of the first and second sets of lateral well bores each substantially extend at an angle of about 45 degrees from the diagonal well bore.

10. The method of claim 8, wherein the area in the subterranean zone is substantially quadrilateral in shape.

11. The method of claim 8, wherein the area in the subterranean zone is substantially square in shape.

12. The method of claim 1, wherein drilling the main well bore and the lateral well bores from the junction into the subterranean zone comprises:

drilling the main well bore and the lateral well bores using an articulated drill string extending through the articulated well bore and the junction;

supplying drilling fluid down through the articulated drill string and back up through an annulus between the articulated drill string and the articulated well bore to remove cuttings generated by the articulated drill string in drilling the main well bore and the lateral well bores;

injecting a drilling gas into the substantially vertical well bore; and

mixing the drilling gas with the drilling fluid at the junction to reduce hydrostatic pressure on the subterranean zone during the drilling of the main well bore and the lateral well bores.

13. The method of claim 12, wherein the drilling gas comprises air.

14. The method of claim 12, wherein the subterranean zone comprises a low-pressure reservoir having a pressure below 250 pounds per square inch (psi).

15. The method of claim 1, wherein drilling the main well bore and the lateral well bores from the junction into the subterranean zone comprises:

drilling the main well bore and the lateral well bores using an articulated drill string extending through the articulated well bore and the junction;

supplying drilling fluid down through the articulated drill string to remove cuttings generated by the drill string in drilling the main well bore and the lateral well bores; and

pumping drilling fluid with cuttings back up through the substantially vertical well bore to reduce hydrostatic pressure on the subterranean zone during drilling of the main well bore and the lateral well bores.

16. The method of claim 15, wherein the subterranean zone comprises an ultra low pressure reservoir having the pressure below 150 pounds per square inch (psi).

17. A system for accessing a subterranean zone from the surface, comprising:

a substantially vertical well bore extending from the surface to the subterranean zone;

an articulated well bore extending from the surface to the subterranean zone, the articulated well bore horizontally offset from the substantially vertical well bore at the surface and intercepting the substantially vertical well bore at a junction proximate to the subterranean zone;

a main well bore extending from the junction into the subterranean zone; and

a plurality of lateral well bores extending from the main well bore into the subterranean zone.

18. The system of claim 17, the junction further comprising an enlarged cavity formed in the substantially vertical well bore proximate to the subterranean zone.

19. The system of claim 17, wherein the subterranean zone comprises a coal seam.

20. The system of claim 17, wherein the subterranean zone comprises an oil reservoir.

21. The system of claim 17, wherein the subterranean zone comprises a low pressure reservoir.

22. The system of claim 17, wherein the subterranean zone comprises an ultra low pressure reservoir having a pressure below 150 pounds per square inch (psi).

23. The system of claim 17, further comprising the substantially vertical rod pumping unit positioned in the substantially vertical well bore and operable to pump fluid drained from the subterranean zone to the junction to the surface.

24. The system of claim 23, wherein the substantially vertical rod pumping unit comprises a sucker rod pump.

25. The system of claim 17, wherein the main well bore comprises a substantially horizontal diagonal well bore extending from the junction defining a first end of an area in the subterranean zone to a distant end of the area, and wherein the plurality of lateral well bores comprises:

a first set of substantially horizontal lateral well bores in space relation to each other extending from the diagonal well bore to the periphery of the area on a first side of the diagonal well bore; and

a second set of substantially horizontal lateral well bores in space relation to each other extending from the diagonal well bore to the periphery of the area on a second, opposite side of the diagonal well bore.

26. The system of claim 25, wherein the first and second sets of lateral well bores each substantially extend at an angle of about 45 degrees from the diagonal well bore.

27. The system of claim 25, wherein the area in the subterranean zone is substantially quadrilateral in shape.

28. The system of claim 25, wherein the area in the subterranean zone is substantially square in shape.

29. A method for preparing a subterranean zone for mining, comprising:

drilling a substantially vertical well bore from the surface to the subterranean zone;

drilling an articulated well bore from the surface to the subterranean zone, the articulated well bore horizontally offset from the substantially vertical well bore at the surface and intercepting the substantially vertical well bore at a junction proximate to the subterranean zone;

drilling through the articulated well bore a substantially horizontal drainage pattern from the junction into the subterranean zone;

draining water from the subterranean zone through the drainage pattern into the junction;

pumping the water from the junction to the surface through the substantially vertical well bore; and

producing gas from the subterranean zone through at least one of the substantially vertical and articulated well bores.

30. The method of claim 29, wherein the junction comprises an enlarged cavity formed in the substantially vertical well bore.

31. The method of claim 29, wherein the subterranean zone comprises a coal seam.

32. The method of claim 29, further comprising:

installing a substantially vertical rod pumping unit in the substantially vertical well bore with a pump inlet position proximate to the junction; and

pumping water from the junction to the surface through the substantially vertical rod pumping unit.

33. The method of claim 29, wherein the subterranean zone comprises a low pressure zone.

34. The method of claim 29, drilling the substantially horizontal draining pattern from the junction comprising:

drilling a diagonal well bore from the junction defining a first end of an area aligned with a subterranean coal panel to an opposite corner of the area; and

drilling a plurality of lateral well bores on each side of the diagonal well bore into one or more coal panels.

35. The method of claim 34, wherein the draining pattern comprises a pinnate structure.

36. The method of claim 29, further comprising rehydrating the subterranean zone after completion of degasification of the subterranean zone by pumping water into the subterranean zone through the drainage pattern.

37. The method of claim 36, further comprising pumping additives into the subterranean zone through the drainage pattern.

38. The method of claim 29, further comprising producing gob gas from the subterranean zone through at least one of the substantially vertical and articulated well bores upon the completion of mining of the area of the subterranean zone into which the draining pattern extends.

39. A method for accessing a subterranean zone from the surface, comprising:

drilling a substantially vertical well bore from the surface to the subterranean zone;

drilling an articulated well bore from the surface to the subterranean zone, the articulated well bore horizontally offset from the substantially vertical well bore at the surface and intersecting the substantially vertical well bore at a junction proximate to the subterranean zone;

drilling a drainage pattern using an articulated drill string extending through the articulated well bore and the junction;

supplying drilling fluid down through the articulated drill string and back up through an annulus between the articulated drill string and the articulated well bore to remove cuttings generated by the articulated drill string in drilling the drainage pattern;

injecting a drilling gas into the substantially vertical well bore; and

mixing the drilling gas with the drilling fluid at the junction to reduce hydrostatic pressure on the subterranean zone during the drilling of the drainage pattern.

40. The method of claim 39, wherein the subterranean zone comprises a low pressure reservoir having a pressure below 250 pounds per square inch (psi).

41. The method of claim 39, wherein the drilling gas comprises air.

42. The method of claim 39, further comprising pumping the drilling fluid back up through the substantially vertical well bore to reduce hydrostatic pressure on the subterranean zone during drilling of the drainage pattern.

43. The method of claim 39, further comprising:

forming an enlarged cavity in the substantially vertical well bore proximate to the subterranean zone;

drilling the articulated well bore to intersect the large cavity of the substantially vertical well bore; and

drilling through the articulated well bore the substantially horizontal drainage pattern from the enlarged cavity into the subterranean zone.

44. The method of claim 43, further comprising:

collecting fluid from the drainage pattern in the enlarged cavity; and

producing the fluid from the enlarged cavity through the substantially vertical well bore.

45. The method of claim 39, wherein the subterranean zone comprises a coal seam.

46. The method claim 39, wherein the subterranean zone comprises an oil reservoir.

47. The method of claim 39, further comprising:

producing fluid from the subterranean zone through the drainage pattern; and

producing the fluid from the drainage pattern through substantially vertical well bore.