Jack up workover rig with removable workover floor unit

• US 6,926,097 B1
• Filed: 03/06/2003
• Issued: 08/09/2005
• Est. Priority Date: 03/06/2002
• Status: Expired due to Fees

• Current Assignee: Michael E. Blake
• Original Assignee: Michael E. Blake
• Inventors: Blake, Michael E.
• Primary Examiner(s): BATES, ZAKIYA W
• Application Number:
  US10/382,607
• Time in Patent Office: 887 Days
• Field of Search: 405/195.1, 405/196, 405203-205, 175/7, 175/9, 175/10, 166/343, 166/354
• US Class Current: 175/9
• CPC Class Codes: E02B 17/021 with relative movement between supporting construction and platform
• CPC Class Codes: E02B 2017/0056 Platforms with supporting legs
• CPC Class Codes: E21B 15/02 specially adapted for underwater drilling E21B15/04 takes precedence

Abstract

An offshore jack-up workover rig. The workover rig includes a vessel which may be self powered or powered by a tug. The vessel may be raised above the surface of a water body by extending the legs until they reach the water body bed and then continuing to extend the legs. The workover rig contains a workover floor unit which includes at least a drawworks, a drawworks motor, and a well aperture. The workover rig is detachably mounted on an extensible cantilevered frame. The frame may be extended to position the workover floor unit over an offshore platform to be serviced. The workover floor unit is also configured to mover laterally relative to the extensible frame. The vessel is also provided with a crane. The crane may be used to lift the detachable workover floor unit from the vessel and deposit it, including its equipment, on the platform.

Claims

1. A jack-up workover rig configured to operate in a water body having a surface and a bed, said workover rig comprising:

a vessel comprising a hull, a deck having an outer perimeter, and a thrust source configured to propel said vessel through said water body;

a jack-up mechanism comprising a plurality of extensible legs, each said leg having a foot end, said jack-up mechanism further comprising at least one jack-up motor configured to raise and lower said legs, whereby said vessel may be raised above the surface of the water body by continuing to extend said legs after said foot ends of said legs reach the bed of the water body;

an extensible cantilevered frame mounted to said vessel;

at least one frame drive configured to extend and retract said cantilevered frame in a direction generally perpendicular to said legs;

a workover floor unit comprising a work platform having a well aperture, drawworks, a derrick, a cable, a workover motor, an accumulator unit, and a choke manifold, said workover floor unit releasably mounted to said cantilevered frame whereby said workover floor unit may be extended past said perimeter of said vessel deck up to a first distance by extending said cantilevered frame; and

a crane positioned on said vessel and configured to lift said workover floor unit from said cantilevered frame, said crane further configured to extend said workover floor unit beyond said first distance from said perimeter of said vessel deck.

2. A jack-up workover rig according to claim 1 wherein said workover floor unit is configured to be horizontally adjustable relative to said extensible frame.

3. A method of servicing an offshore platform using a jack-up workover rig configured to operate in a water body having a surface and a bed, said workover rig comprising a vessel comprising a hull, a deck having an outer perimeter, and a thrust source configured to propel said vessel through said water body, said vessel containing a plurality of skid beams;

a jack-up mechanism comprising a plurality of extensible legs, each said leg having a foot end, said jack-up mechanism further comprising at least one jack-up motor configured to raise and lower said legs;

an extensible cantilevered frame mounted to said vessel;

at least one frame drive configured to extend and retract said cantilevered frame in a direction generally perpendicular to said legs;

a workover floor unit comprising a work platform having a well aperture, drawworks, a derrick, a cable, a workover motor, an accumulator unit, and a choke manifold, said workover floor unit releasably mounted to said cantilevered frame whereby said workover floor unit may be extended past said perimeter of said vessel deck by extending said cantilevered frame; and

a crane positioned on said vessel;

wherein the method comprises;

positioning said vessel in said water body adjacent to said offshore platform;

extending said legs until said foot ends of said legs reach the bed of the water body;

continuing to extend said legs until said vessel deck reaches a desired height above said offshore platform;

positioning at least two of said skid beams on said offshore platform with said crane;

extending said cantilevered frame until said workover floor unit is positioned over said skid beams on said offshore platform;

retracting said legs until said workover floor unit is resting on said skid beams on said offshore platform;

releasing said workover floor unit from said cantilevered frame;

engaging said skid beams with said cantilevered frame; and

driving said skid beams by extending said cantilevered frame until said workover floor unit is positioned at a desired location on said offshore platform.

4. A method of servicing an offshore platform using a jack-up workover rig configured to operate in a water body having a surface and a bed, said workover rig comprising a vessel comprising a hull, a deck having an outer perimeter, and a thrust source configured to propel said vessel through said water body, said vessel containing a plurality of skid beams;

a jack-up mechanism comprising a plurality of extensible legs, each said leg having a foot end, said jack-up mechanism further comprising at least one jack-up motor configured to raise and lower said legs, whereby said vessel may be raised above the surface of the water body by continuing to extend said legs after said foot ends of said legs reach the bed of the water body;

a workover floor unit comprising a work platform having a well aperture, drawworks, a derrick, a cable, a workover motor, an accumulator unit, and a choke manifold, said workover floor unit releasably mounted to said vessel; and

a crane positioned on said vessel and configured to lift said workover floor unit from said vessel, said crane further configured to extend said workover floor unit beyond said perimeter of said vessel deck wherein the method comprises;

positioning said vessel in said water body adjacent to said offshore platform;

extending said legs until said foot ends of said legs reach the bed of the water body;

continuing to extend said legs until said vessel deck reaches a desired height above said offshore platform;

positioning at least two of said skid beams on said offshore platform with said crane;

releasing said workover floor unit from said vessel;

moving said workover floor unit from said vessel and positioning said workover floor unit on said skid beams on said offshore platform with said crane.