Multiple Activity Rig

• US 20070251725A1
• Filed: 06/01/2005
• Published: 11/01/2007
• Est. Priority Date: 06/02/2004
• Status: Active Grant

• Current Assignee: Stena Drilling Limited (Stena Sphere)
• Original Assignee: Stena Drilling Limited (Stena Sphere)
• Inventors: Banks, John
• Granted Patent: US 8,678,094 B2
• Time in Patent Office: Days
• US Class Current: 175/5
• CPC Class Codes: E21B 19/002 specially adapted for underwater drilling E21B19/09, E21B19/143 take precedence
• CPC Class Codes: E21B 19/004 supporting a riser from a drilling or production platform
• CPC Class Codes: E21B 19/14 Racks, ramps, troughs or bins, for holding the lengths of rod singly or connected; Handling between storage place and borehole E21B19/20, E21B19/22 take precedence
• CPC Class Codes: E21B 19/143 specially adapted for underwater drilling

Abstract

An offshore platform may include a pair of trolleys. One trolley may be mounted on top of the platform and the other trolley may be suspended below the platform. Each trolley may be positioned on opposed sides of a moon pool in one embodiment of the present invention. The lower trolley may be used to hang off a riser and blowout preventer. The upper trolley may be utilized to hang off smaller diameter casing while larger diameter casing is being made up and positioned within the hole. As a result of the parallel operations made possible by the trolleys, drilling time may be reduced in some embodiments.

Claims

1. A method comprising:

hanging off smaller diameter casing from an offshore drilling platform while positioning a larger diameter casing.

2. The method of claim 1 including hanging off the smaller diameter casing from a trolley mounted on said platform.

3. The method of claim 2 including repositioning the smaller diameter casing by rolling the trolley into position over the larger diameter casing in position within the seabed floor.

4. The method of claim 3 including jetting in the larger diameter casing.

5. The method of claim 4 including inserting a drill string through the larger diameter casing to drill a hole for the smaller diameter casing.

6. The method of claim 5 including lowering the smaller diameter casing into the hole below the larger diameter casing.

7. The method of claim 1 including hanging off a blowout preventer and riser from said platform.

8. The method of claim 7 including hanging off a blowout preventer and riser from a lower trolley on said platform and hanging off said casing from an upper trolley on said platform.

9. The method of claim 1 including using a platform with a single derrick.

10. The method of claim 8 including providing an extension on a moon pool in said platform and providing a mating extension on the upper trolley and providing a split ring bearing on said lower trolley to enable riser to be lifted from said moon pool extension and positioned over the moon pool.

11. An offshore drilling platform comprising:

a deck;

a first trolley to hang off a riser and blowout preventer; and

a second trolley coupled to said deck to hang off casing.

12. The platform of claim 11 wherein said first trolley is mounted over the deck.

13. The platform of claim 12 wherein said second trolley is mounted below said deck.

14. The platform of claim 13 wherein said second trolley includes a split ring bearing to hold said riser and blowout preventer.

15. The platform of claim 11 including a moon pool with a moon pool extension.

16. The platform of claim 15 including only one derrick.

17. The platform of claim 15 wherein said first trolley includes a slot to mate with said moon pool extension.

18. The platform of claim 11 including a device to lift casing from said moon pool extension onto said second trolley.

19. The platform of claim 11 wherein said first and second trolleys are positionable on opposite sides of said moon pool.

20. The platform of claim 11 wherein said platform is a floating platform.