Dual Drilling Activity Drilling Ship

• US 20110247827A1
• Filed: 04/07/2010
• Published: 10/13/2011
• Est. Priority Date: 04/07/2010
• Status: Abandoned Application

• Current Assignee: Stena Drilling Limited (Stena Sphere)
• Original Assignee: Stena Drilling Limited (Stena Sphere)
• Inventors: Humphreys, Gavin
• Application Number:
  US12/755,565
• Publication Number:
  US 20110247827A1
• Time in Patent Office: Days
• US Class Current: 166/345
• CPC Class Codes: B63B 35/4413 Floating drilling platforms, e.g. carrying water-oil separating devices
• CPC Class Codes: E21B 15/02 specially adapted for underwater drilling E21B15/04 takes precedence
• CPC Class Codes: E21B 7/12 Underwater drilling using heave compensators E21B19/09

Abstract

A single drilling ship may be equipped with two drilling centers, each capable of running risers. Each drilling center has a set of tubulars stored for use in association with that drilling center, those tubulars including risers. However, the risers for one drilling center are of a smaller diameter than the risers for the other drilling center. In the event that a main drilling center drilled well fails, a relief well can then be drilled from the same ship using a secondary drilling center.

Claims

1. A method comprising:

outfitting a drilling ship with two separate and distinct drilling centers, each capable of drilling a well; and

providing marine risers for each of said drilling centers, the marine risers for one of the drilling centers being of a smaller diameter than the marine risers for the other of said drilling centers.

2. The method of claim 1 including providing storage for marine risers in association with each of said drilling centers.

3. The method of claim 1 including providing equipment to enable a relief well to be drilled from the same ship that drilled a failed well.

4. The method of claim 1 including, in association with a secondary drilling center having smaller diameter risers, providing two blowout preventers.

5. The method of claim 4 including permanently installing riser tensioners on said secondary drilling center.

6. The method of claim 1 including connecting risers to a lower blowout preventer using a lower marine riser package.

7. The method of claim 6 including providing an upper blowout preventer between said tensioner and said risers.

8. The method of claim 4 including providing a lower marine riser package between a blowout preventer on said secondary drilling center and said risers.

9. The method of claim 1 including providing a mechanical override emergency riser disconnector on the drilling center with larger diameter risers.

10. The method of claim 9 including connecting the disconnector to a lower marine riser package.

11. The method of claim 1 including providing a subsea shutoff assembly for the drilling center with the larger diameter risers.

12. A drilling ship comprising:

a first drilling center including storage to store first marine risers;

a second drilling center to drill a second well from the same ship, the second drilling center including storage to store second marine risers, said second marine risers having a smaller diameter than said first marine risers.

13. The ship of claim 12 to enable a relief well to be drilled from said second drilling center when a well drilled from said first drilling center has failed.

14. The ship of claim 12 including two blowout preventers for said second drilling center.

15. The ship of claim 14 including a riser tensioner permanently installed on said second drilling center.

16. The ship of claim 14 including a lower blowout preventer connected to the marine risers via a lower marine riser package.

17. The ship of claim 16 including an upper blowout preventer between said tensioner and said risers.

18. The ship of claim 14 including a lower marine riser package between a blowout preventer on said second drilling center and said risers.

19. The ship of claim 12 including a mechanical override emergency riser disconnector on the second drilling center.

20. The ship of claim 19 including said disconnector connected to a lower marine riser package.

21. The ship of claim 12 wherein said second drilling center includes two blowout preventers and said first drilling center includes only one blowout preventer.