Wellbore plug system and method

• US 6,991,048 B2
• Filed: 07/12/2002
• Issued: 01/31/2006
• Est. Priority Date: 07/12/2002
• Status: Expired due to Fees

• Current Assignee: Effective Exploration LLC
• Original Assignee: CDX Gas LLC (EnerVest Ltd.)
• Inventors: Zupanick, Joseph A.
• Primary Examiner(s): NEUDER, WILLIAM P
• Application Number:
  US10/194,422
• Publication Number:
  US 20040007390A1
• Time in Patent Office: 1,299 Days
• Field of Search: 166/313, 166/50, 166/117.6, 125/61, 125/62, 125/8.F
• US Class Current: 175/61
• CPC Class Codes: E21B 41/0035 Apparatus or methods for multilateral well technology, e.g. for the completion of or workover on wells with one or more lateral branches
• CPC Class Codes: E21B 41/0042 characterised by sealing the junction between a lateral and a main bore
• CPC Class Codes: E21B 7/061 the tool shaft advancing relative to a guide, e.g. a curved tube or a whipstock

Abstract

In accordance with one embodiment of the present invention, a method for drilling wellbores includes drilling a main wellbore, disposing a casing string having a deflecting member at a lower end thereof in the main wellbore, disposing a drill string having a drill bit at a lower end thereof in the casing string, and drilling, with the drill bit, a first lateral wellbore at a first depth in the main wellbore. The method further includes transferring the casing string to a second depth in the main wellbore that is less than the first depth, disposing a first temporary plug in the main wellbore at the second depth to prevent gas from flowing up the main wellbore past the second depth, transferring the casing string to a third depth in the main wellbore that is less than the second depth, and drilling, with the drill bit, a second lateral wellbore at the third depth.

Claims

1. A method for drilling wellbores, comprising:

drilling a main wellbore;

disposing a casing string having a deflecting member at a lower end thereof in the main wellbore;

disposing a drill string having a drill bit at a lower end thereof in the casing string;

drilling, with the drill bit, a first lateral wellbore at a first depth in the main wellbore;

transferring the casing string to a second depth in the main wellbore that is less than the first depth;

disposing a first temporary plug in the main wellbore at the second depth to prevent gas from flowing up the main wellbore past the second depth without removing the casing string from the main well bore;

transferring the casing string to a third depth in the main wellbore that is less than the second depth;

drilling, with the drill bit, a second lateral wellbore at the third depth; and

removing the first temporary plug, wherein removing the first temporary plug comprises either drilling through the first temporary plug or dissolving the first temporary plug.

2. The method of claim 1, further comprising:

transferring the casing string to a fourth depth in the main wellbore that is less than the third depth;

disposing a second temporary plug in the main wellbore at the fourth depth to prevent gas from flowing up the main wellbore past the fourth depth; and

drilling, from the main wellbore, a third lateral wellbore at a fifth depth in the main wellbore that is less than the fourth depth.

3. The method of claim 1, further comprising:

extracting the casing string and the drill bit away from the third depth.

4. The method of claim 1, wherein drilling the main wellbore comprises drilling a slant wellbore.

5. The method of claim 1, wherein the first temporary plug is formed from a material selected from the group consisting of a polymer, a bentonite clay, a mechanical plug, a gel plug, and a cement plug.

6. The method of claim 1, further comprising disposing the casing string in the main wellbore such that an outer annulus is formed between a wall of the main wellbore and an outer wall of the casing string, and disposing the drill string in the casing string such that an inner annulus is formed between an inner wall of the casing string and an outer wall of the drill string.

7. The method of claim 6, further comprising:

circulating a first fluid down an inner passage of the drill string;

circulating a second fluid down the inner annulus; and

retrieving a mixture of the first and second fluids and the gas from the lateral wellbore through the outer annulus.

8. The method of claim 6, further comprising:

circulating a first fluid down an inner passage of the drill string;

circulating a second fluid down the outer annulus; and

retrieving a mixture of the first and second fluids and the gas from the lateral wellbore through the inner annulus.

9. A method for drilling wellbores, comprising:

drilling a main wellbore;

drilling a plurality of lateral wellbores from the main wellbore, the lateral wellbores being drilled at successively lesser depths;

disposing a temporary plug in the main wellbore at a depth above the depth of at least one of the lateral wellbores; and

removing the temporary plug after drilling is complete, wherein removing the temporary plug comprises either drilling through or dissolving the temporary plug.

10. The method of claim 9, wherein drilling the main wellbore comprises drilling a slant wellbore.

11. The method of claim 9, wherein each temporary plug is formed from a material selected from the group consisting of a polymer, a bentonite clay, a mechanical plug, a gel plug, and a cement plug.

12. A method for drilling wellbores, comprising:

drilling a main wellbore;

disposing a casing string having a deflecting member at a lower end thereof in the main wellbore;

disposing a drill string having a drill bit at a lower end thereof in the casing string;

drilling, with the drill bit, a first lateral wellbore at a first depth in the main wellbore;

disposing a first temporary plug in the first lateral wellbore adjacent the main wellbore to prevent gas from flowing from the first lateral wellbore without removing the casing string from the main well bore;

transferring the casing string and the drill bit to a second depth in the main wellbore that is less than the first depth;

drilling, with the drill bit, a second lateral wellbore at the second depth; and

removing the first temporary plug, wherein removing the first temporary plug comprises either drilling through the first temporary plug or dissolving the first temporary plug.

13. The method of claim 12, further comprising:

disposing a second temporary plug in the second lateral wellbore adjacent the main wellbore to prevent gas from flowing from the second lateral wellbore;

transferring the casing string and the drill bit to a third depth in the main wellbore that is less than the second depth; and

drilling, from the main wellbore, a third lateral wellbore at the third depth.

14. The method of claim 12, wherein drilling the main wellbore comprises drilling a slant wellbore.

15. The method of claim 12, wherein the first temporary plug is formed from a material selected from the group consisting of a polymer, a bentonite clay, a mechanical plug, a gel plug, and a cement plug.

16. The method of claim 12, further comprising disposing the casing string in the main wellbore such that an outer annulus is formed between a wall of the main wellbore and an outer wall of the casing string, and disposing the drill string in the casing string such that an inner annulus is formed between an inner wall of the casing string and an outer wall of the drill string.

17. The method of claim 16, further comprising:

circulating a first fluid down an inner passage of the drill string;

circulating a second fluid down the inner annulus; and

retrieving a mixture of the first and second fluids and the gas from the lateral wellbore through the outer annulus.