US3517739A - Apparatus for supporting a tubular member at the ocean floor - Google Patents

Description

June so, 1970 P.- R. ROWLEY APPARATUS FOR SUPPORTING A TUBULAR MEMBER AT THE OCEAN FLOOR Filed Dec. 26. 1967 3 Sheets-Sheet l INVENTOR. PAUL E. Eon/LEV A TTOENEK P. R. ROWLEY June 30, 1970 APPARATUS FOR SUPPORTING A TUBULAR MEMBER AT THE OCEAN FLOOR Filed Dec. 26. 1967 3 Sheets-Sheet 3 INVENTOR. PAUL e. earl/LEV BY l 4 r Toe/v54 June 30, 1970 P. R. ROWLEY 3,517,739-

APPARATUS FOR SUPPORTING A TUBULAR MEMBER AT THE OCEAN FLOOR Filed Dec. 26, 1967 5 Sheebs-Sheet 5 INVENTOR. PAUL 2. eon 4E) ATTOENEK United States Patent US. Cl. 166-.6 8 Claims ABSTRACT OF THE DISCLOSURE This application discloses a benthonic well head slip assembly and an apparatus and method for supporting at the ocean floor, a drill pipe or other tubular member extending between a drilling vessel floating over the well and the ocean floor, to prevent relative movement between said drill pipe and the blowout preventers when the blowout preventers are closed around the drill pipe or tubular member.

I Blowout preventers which seal around a drill pipe or other tubular member passing therethrough and close off the well in the event of a high pressure condition downhole, are used in benthonic well head equipment for drilling wells through the ocean floor. According to conventional offshore drilling practices, a drill pipe or other tubular member extending from the drilling vessel into the well is supported from the drilling vessel at the surface of the body of water. The effect of the waves on the body of water is to move the vessel up and down and hence move the drill pipe up and down within the blowout preventers-which results in wear on the blowout preventers sealing elements which sealingly engage the drill pipe. When the blowout preventers are thus closed around the drill pipe for a prolonged time, the blowout preventers sealing elements wear out and must be replaced. Replacement of blowout preventer sealing elements generally requires round-tripping the riser and closing in the well, which are both time consuming and costly. My present invention involves a system whereby the wear of the blowout preventer sealing elements issubstantially eliminated even though the blowout preventer is closed off around the drill pipe for prolonged periods.

Accordingly, it is an objectof my present invention to provide an offshore drilling system which will effectively eliminate the need for replacement of the blowout preventer sealing elements due to wear caused by wave motion of the vessel whilethe blowout preventer is closed off around the drill pipe.

It is also an object of my present invention to provide an apparatus for supporting a drill pipe or other tubular member extending from a floating vessel to a well drilled into the ocean floor.

It is also an object of my present invention to provide a novel drill pipe slip assembly to support a drill pipe extending between a floating vessel into a well drilled into the ocean floor.

' It is a further object of my present invention to provide a method for preventing wear on blowout preventer sealing elements by axial movement of a drill pipe or other tubular member extending from a floating vessel to a benthonic well while the blowout preventer is closed ofi around said drill pipe.

Other objects and a more complete understanding of my present invention may be had by reference to the Patented June 30, 1970 ice FIG. 1 shows, partially in section, a blowout preventer assembly utilizing my present invention, positioned on the ocean floor during drilling operations;

FIG. 2 shows an enlarged perspective view of the slip retainer assembly structure employed according to one embodiment of my present invention;

FIG. 3 shows a further enlarged perspective view of a slip segment of the slip retainer assembly shown in FIG. 2; and

FIG. 4 shows a view of another embodiment of my present invention, particularly in section, wherein a double gate valve blowout preventer is adapted in accordance with my present invention.

With reference to the drawings generally, a hydraulically controlled slip assembly 10 is shown in FIG. 1 in a blowout preventer stack positioned on the ocean floor in a benthos well 12 drilled from a structure such as vessel 14, floating on the body of water 11, with a drill pipe 16 extending through a riser 18. When the sealing elements of blowout preventers 20 and 22 are closed off around the drill pipe 16, the slip assembly 10- is actuated remotely through hydraulic hoses'24 and 26 to actuate the slips 28 within the slip assembly 10 to support the drill pipe 16 at the ocean floor. The drill pipe is released from vertical restraint at the vessel while it is supported at the ocean floor with the slip assembly 10 and thus the vessel 14 is free to rise and fall with the ocean waves, around the drill pipe 16 as it normally does around the riser 18. The slip retainer assembly 42 from the unit 10 is shown in FIG. 2, and FIG. 3 shows an enlarged view of an individual slip segment 44. FIG.

following specification and the appended claims, when taken in conjunction with the drawings, wherein:

4 shows a pair of double control gates modified to perform the function of the hydraulic slip assembly 10 shown in FIG. 1.

Referring now more particularly to FIG. 1, a well 12 is drilled into the ocean floor by conventional drilling means from a floating vessel 14 and conductor casing 30 and surface pipe 32 cemented therein in accordance with conventional practice. The drill pipe is normally supported vertically at the vessel, either by slips in the rotary table or by elevators which are supported by the traveling block from the derrick. The blowout preventer stack (comprising units 20, 22, and 10 in FIG. 1) may be lowered to the ocean floor on either the drill pipe 16 or on the riser pipe 18 and is aflixed to the upper. end of the surface pipe 32 by any conventional means such as a safety release joint, a flanged Sub, or the like. Above the release joint 31 is the slip assembly 10, and above that, conventional blowout preventers 20 and 22. On top of the blowout preventer 20 is a latch means or another safety release joint 34 for connecting the lower end of the riser 18 to the blowout preventer stack.

The hydraulic slip assembly 10, as shown in FIG. .1,

is a conventional remotely controlled hydraulic means for engaging and disengaging the exterior surface of a drill pipe or other tubular member, at a predetermined time, for example, when blowout preventer equipment is closed off around the drill pipe. As shown in FIG. 1, a Hydril type blowout preventer is adopted in accordance with my present invention and a piston 36- is movable within the slip assembly housing 38 when hydraulic pressure is applied to the cylinder 40 through the hydraulic hose 24. A- slipretainer assembly 42 is positioned inside the piston 36, for engagement of the drill pipe by the inner face of the slip retainer assembly. As best shown in FIG. 2, the slip retainer assembly 42 comprises a series of I shaped metal segments 44, embedded in a rubber matrix 46. A single slip segment 44 is shown in FIG. 3 separately. The top portion 38a of the. slip assembly housing 38 engages the upper surface 48 of the segment assembly 42 within the housing 38. Upward movement of the piston 36 squeezes the slip retainer assembly unit 42 inward to cause the button slips 28 to engage the drill pipe 16 and thus firmly hold the drill pipe and prevent vertical movement thereof. The inner surface of the segments 48 is provided with a series of vertically spaced holding slips 28 which may be conventional oil field button slips. The

drill pipe or tubular member which is engaged by the slips can be released by exerting hydraulic pressure through hydraulic hose 26 to pressurize cylinder 52 and thus move the piston 36 downward. The Hydril-type blowout preventer assembly which has been modified by the provision of button slips on the inner face thereof is described more fully in the 1966-67 Composite Catalog of Oil Field Equipment, published by the Gulf 'Publishing (30., pages 2667 and 2669.

With reference to the apparatus shown in FIGS. 1, 2, and 3, the method of my present invention is practiced when the blowout preventers 20 and 22 are closed around the drill pipe 16 by pressurizing cylinder 40 to engage the drill pipe with slips 28 of slip segments 44, and releasing the drill pipe at the vessel 14 by removing the elevators 94 and slips 92 in the rotary table 90 from the drill pipe so that the vessel is free to move vertically around the drill pipe 16. The riser is supported in the moon pool 15 by any conventional means such as cables 96 and hence the vessel 14 is free to move vertically around the riser also.

FIG. 4 shows another type of hydraulically actuated slip assembly wherein slip segments 54 are inserted on the inner faces of the drill pipe rams 56 of a Shaifer or double gate-type blowout preventer assembly. The slip unit 58 comprises the lower end of a blowout preventer stack which is attached to the lower end of a riser extending from the drilling vessel (not shown) and is attached to the ocean floor by engagement of the lower rams 60 within the shoulder 62 of a surface casing mandrel 64. In this Shaffer-type blowout preventer unit 58, both the rams 56 and 60 are laterally movable and rams 60 may be laterally moved outwardly to disconnect the blowout preventer stack from the surface pipe landing mandrel 64. Slip rams 56 may also be retracted laterally to disengage the slip elements 54 from the tubular member 66.

Another conventional double gate blowout preventer '68 is positioned above the hydraulic slip assembly 58 and interspaced therefrom with spool 70. The blowout preventer 68 contains drill pipe rams 72 and complete shutofi rams 74. The double control gates 58 and 6 8 may be either hydraulically or electrically operated. In the apparatus shown in FIG. 4, the surface pipe 63 and the conductor sub 76 are cemented with base 78 to the ocean floor 80.

Hence it can be seen that from the apparatus described above, during offshore drilling operations when it is nec essary to close an ocean floor blowout preventer around a tubular member such as a drill string, tubing string, casing, etc., the weight of the tubular member can be supported at the ocean floor with hydraulically actuated slips mounted on a conductor pipe, either below or above the blowout preventer stack, to thus eliminate the relative motion between the tubular member and the blowout preventer which eventually wears out the sealing elements in the blowout preventer. The slip assembly may be positioned above or below the blowout preventer, however, if it is positioned below the blowout preventer it is preferred that a segmented type slip assembly be employed so that the fluids can be circulated in the annulus between the tubular member and the slip assembly past the slip elements.

Various modifications of my present invention can be made without departing from the spirit of my invention and my invention should not be limited to the embodiments set forth herein above, but should be afforded the full scope of the appended claims wherein I claim:

1. Apparatus for conducting drilling and production operations in a benthos well with a tubular string extending from a floating structure into said well through a blowout preventer positioned proximate the well opening, the improvement comprising:

slip means adjacent said blowout preventer for supporting said tubular member proximate said well opening when said blowout preventer is sealingly closed around said tubular member, and means for actuating said slip means.

2. Apparatus for conducting drilling and production operations in a benthos well with a tubular string extending from a floating structure into said well through a blowout preventer positioned proximate the well opening, the improvement comprising:

slip means adjacent said blowout preventer for supporting said tubular member proximate said well opening when said blowout preventer is sealingly closed around said tubular member, said slip means comprising a slip retainer assembly having segmented slips, and means for actuating said slip means.

3. The apparatus of claim 2 including means for releasing said tubular member at said structure whereby said structure is free to move vertically with respect to said tubular member.

4. The apparatus of claim 2 wherein said slip means comprises a housing having said slip retainer assembly therein and means for remotely laterally moving the slip segments of said slip retainer assembly into and out of engagement with said tubular member.

5. The apparatus of claim 3 wherein said laterally movable means are hydraulically actuated from a remote location.

6. The apparatus of claim 3 wherein said laterally movable means comprise a piston movable within said housing between two cylinders, and means for alternately admitting hydraulic pressure to said cylinders to move said piston up and down.

7. The apparatus of claim 3 wherein said laterally movable means are hydraulically actuated rams.

8. Apparatus for conducting drilling and production operations in a benthos well with a tubular string extending from a floating structure into said well through a blowout preventer positioned proximate the well opening, the improvement comprising:

slip means adjacent said blowout preventer for supporting said tubular member proximate said well opening when said blowout preventer is sealingly closed around said tubular member, said slip means comprising a housing having a slip retainer assembly therein, said assembly including segmented slips arranged to permit circulation of fluid in the annulus bet-ween said slip retainer assembly and said tubular member past said supporting means, said slip means being positioned below said blowout preventer, means for laterally moving said slip retainer assembly into and out of engagement with said tubular member, and means for actuating said slip means.

References Cited UNITED STATES PATENTS 3,137,348 6/ 1964 Ahlstone et al. 166-.6 3,179,179 4/ 1965 Kofahl 166.5 3,215,203 11/1965 Sizer 166-.5 X 3,219,118 11/1965 Lewis 166-.6 3,353,594 11/1967 Lewis 166-.6 3,411,576 11/1968 Taylor 166.5

DAVID H. BROWN, Primary Examiner U.S. Cl. X.R. 166--72

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