Self-elevating drilling unit drills petroleum well offshore with wellhead on seabed
First Claim
1. A method for employing a self-elevating drilling unit (SEDU) for drilling and completing a subsea well in a marine environment having a water surface and a seabed, said SEDU having a vessel hull, a plurality of moveable vessel support legs of sufficient length to extend from said vessel into the seabed for lifting the vessel hull a desired height above the water surface and having a cantilevered housing projecting laterally from said vessel hull and positioning a derrick and well drilling system supported by said cantilevered housing for well drilling, said well drilling system having a rotary drilling table within said cantilevered housing and in alignment with said wellhead, said rotary drilling table having a central opening, said method comprising:
- providing a well installation having a conductor pipe penetrating a desired depth into a seabed and having a wellhead permanently located at the seabed;
positioning said SEDU with said derrick and rotary drilling table of said cantilevered housing above the water surface and in alignment with said wellhead;
positioning a blowout preventer (BOP) stack having a plurality of connected BOP units within said cantilevered housing and being moveable within said cantilevered housing for alignment with said rotary drilling table;
providing multiple drilling spools each having upper and lower connection flanges and each having an internal circular spool handling groove therein;
securing a wellhead connector member to the lower end connection flange of said lower drilling spool;
positioning a drilling spool running tool within said lower drilling spool and establishing handling engagement with said internal circular spool handling groove thereof and lowering said lower drilling spool within said central opening of said rotary drilling table;
supporting said lower drilling spool relative to said rotary drilling table with a spider mechanism;
with said drilling spool running tool engaging said internal circular groove of successive drilling spools and connecting them in end to end relation forming a drilling spool string having plurality of tubular drilling spools in sealed and pressure containing relation;
connecting said wellhead connector to said wellheadconnecting an uppermost tubular drilling spool of said drilling spool string with said BOP stack; and
drilling and completing said subsea well through said BOP stack, said drilling spool string, said wellhead connector and said wellhead.
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Accused Products
Abstract
A method and apparatus for drilling wells for producing petroleum products from an earth formation that is covered by shallow water having a depth of about 600′ or less, using a self-elevating drilling unit (SEDU) to drill one or more wells having wellheads located at or near the seabed. Well drilling is accomplished through a blowout preventer stack and a drilling spool string having a wellhead connector secured at its lower end and establishing releasable connection with the subsea wellhead. As a plurality of wells are being drilled, production of petroleum products can begin from wells that have already been completed, thus initiating an income stream from petroleum production starting only a few months from initiation of well drilling activity. When a well has been drilled, completed and rendered safe, the drilling spool string and wellhead connector is removed to the SEDU, leaving the wellhead positioned at the seabed in readiness for later production.
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Citations
15 Claims
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1. A method for employing a self-elevating drilling unit (SEDU) for drilling and completing a subsea well in a marine environment having a water surface and a seabed, said SEDU having a vessel hull, a plurality of moveable vessel support legs of sufficient length to extend from said vessel into the seabed for lifting the vessel hull a desired height above the water surface and having a cantilevered housing projecting laterally from said vessel hull and positioning a derrick and well drilling system supported by said cantilevered housing for well drilling, said well drilling system having a rotary drilling table within said cantilevered housing and in alignment with said wellhead, said rotary drilling table having a central opening, said method comprising:
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providing a well installation having a conductor pipe penetrating a desired depth into a seabed and having a wellhead permanently located at the seabed; positioning said SEDU with said derrick and rotary drilling table of said cantilevered housing above the water surface and in alignment with said wellhead; positioning a blowout preventer (BOP) stack having a plurality of connected BOP units within said cantilevered housing and being moveable within said cantilevered housing for alignment with said rotary drilling table; providing multiple drilling spools each having upper and lower connection flanges and each having an internal circular spool handling groove therein; securing a wellhead connector member to the lower end connection flange of said lower drilling spool; positioning a drilling spool running tool within said lower drilling spool and establishing handling engagement with said internal circular spool handling groove thereof and lowering said lower drilling spool within said central opening of said rotary drilling table; supporting said lower drilling spool relative to said rotary drilling table with a spider mechanism; with said drilling spool running tool engaging said internal circular groove of successive drilling spools and connecting them in end to end relation forming a drilling spool string having plurality of tubular drilling spools in sealed and pressure containing relation; connecting said wellhead connector to said wellhead connecting an uppermost tubular drilling spool of said drilling spool string with said BOP stack; and drilling and completing said subsea well through said BOP stack, said drilling spool string, said wellhead connector and said wellhead. - View Dependent Claims (2, 3)
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4. Apparatus for drilling and completing a subsea well having a conductor pipe extending to a desired depth within a seabed and having a wellhead located at the seabed, comprising:
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a self-elevating drilling unit (SEDU) having a vessel hull, a plurality of moveable vessel support legs of sufficient length to extend from said vessel hull and into the seabed for lifting said vessel hull a desired height above the water surface; a cantilevered housing projecting laterally from said vessel hull and having a derrick having a well drilling mechanism and an elevator mechanism; a rig floor being located on said cantilevered housing and defining a drilling opening, said cantilevered housing having moveable support and positioning apparatus below said rig floor providing support for well drilling apparatus and being selectively moveable fore, aft, port, and starboard for positioning said well drilling apparatus in alignment with said drilling opening within said cantilevered housing; a rotary table being positioned at said drilling opening of said rig floor and having a rotary table opening through which well drilling operations are conducted; a blowout preventer stack being located within said cantilevered housing and being supported and positioned for well drilling operations by said moveable support and positioning apparatus; a plurality of well drilling spools being mounted end to end and forming a drilling spool string having a length for extending from said blowout preventer stack to said subsea wellhead; each of said plurality of well drilling spools having an internal circular drilling spool handling groove; a drilling spool running tool being positionable within selected well drilling spools and in drilling spool handling engagement with said internal circular drilling spool handling groove and being moveable to position the selected well drilling spool in end to end relation with another well drilling spool of said well drilling string for connection therewith; and a wellhead connector being mounted to said well drilling spool string and being hydraulically actuated for locking and releasing relation with said subsea wellhead. - View Dependent Claims (5, 6, 7, 8, 9)
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10. Apparatus for drilling and completing a subsea well having a conductor pipe extending to a desired depth within a seabed and having a wellhead located at the seabed and a blowout preventer located on a marine well drilling vessel, comprising:
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a first wellhead connector being mounted to said wellhead; a bottom well drilling spool having a second wellhead connector connected with the bottom end of said bottom well drilling spool and being selectively connected to and disconnected from said first wellhead connector; a top well drilling spool being connected with said blowout preventer; a plurality of intermediate well drilling spools being connected in end to end relation and together with said bottom and top well drilling spools defining a pressure containing tubular well drilling spool string through which well drilling operations are conducted; each of said top, bottom and intermediate well drilling spools defining an internal passage and having a circular well drilling spool handling groove therein; a drilling spool running tool being selectively positioned within said internal passage of a selected well drilling spool and having spool handling engagement within said drilling spool handling groove; and a derrick and elevator mechanism being mounted to said marine well drilling vessel, said elevator mechanism being selectively connected with said drilling spool running tool and selectively lifting and lowering said drilling spool running tool and said selected well drilling spool or drilling spool string for well drilling and for connecting and disconnecting said first and second wellhead connectors. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification