US3621912A - Remotely operated rotating wellhead - Google Patents

Abstract

A remotely operated rotating wellhead having a sealing element made of resilient material and a bearing element. The sealing element which is energized by pressure fits inside of and rotates with the bearing element. A retaining cap is provided with retractable, remotely operated latches to permit replacing the sealing element remotely. The lower end of the rotating wellhead is attached to the upper end of a blowout preventer (BOP) stack through suitable subsea connectors.

Description

United States Patent [72] inventors Lemuel D. Wooddy, Jr. 2,192,805 3/1940 Seamark 277/31 Houston, Tex.; 2,909,359 10/1959 Bauer et al.. 175/7 Hubert P. Bezner, Chatsworth, Calif. 3,023,012 2/ 1 962 Wilde 277/31 [21] App]. No. 883,726 3,387,851 6/1968 Cugini 277/31 X [22] Filed Dec. 10,1969 3,492,007 1/1970 Jones 277/31 x2512: Research Com an Primary Examiner-Marvin A. Champion g p y Assistant Examiner- Richard E. Favreau Attorneys-Timothy L. Burgess, Thomas B. McCullouch, [54 REMOTELY OPERATED WELLHEAD Melvin F. Fincke, John S. Schneider, Sylvester W. Bl'OCk,

4 Claims, 2 Drawing Figs. and Kurt Myers [52] US. Cl 166/.5,

277/31 ABSTRACT: A remotely operated rotating wellhead having a {51 Int. Cl E2lb 33/035 sealing element made of resilient material and a bearing ele- [50] Field of Search 175/7; The sealing eIemem which is energized y Pl"?Ssure m5 277/31; 166/5 inside of and rotates with the bearing element. A retaining cap is provided with retractable, remotely operated latches to per- References Cited mit re lacin the sealin element remotel The lower end of P g g Y UNITED STATES PATENTS the rotating wellhead is attached to the upper end of a blowout 1,942,366 1/1934 Seamark 277 31 (BOP) sack hmugh Suimble Subs DRILL PIPE IO '2 RETAINER L 1' PL ATE 27 33 ASiESMBI-Y 46 47 33 27 LUBE LINE SEALING ELEMENT 34 I 40 30 y l J] 4| HY DRAULIC LINE 2 MUD RETURN PATENTEnuuv 23 l97| sum 1 [1F 2 DRILLING BARGE DRILL PIPE- GUIDE LINES:

ROTATING HEAD GUIDE SLEEVE B.O.P. STAG K WELL-HEAD MUD RETURN LINE FIG. I.

' l as ,-FLEXIBLE JOINT \CONNECTOR couulgc'ron INVEN'IOR. LEMUEL D. WOODDY, JR.,

HUBERT P. BEZNER,

WWI M AT TORNEY.

I BY

PATENIEnudv 23 new: 3, 5 21 ,9 1 2 SHEET 2 0F 2 DRILL PIPE l0 Lg RETAINER PLATE LATCH M$SEMBLY 27 46 47 33 33 45 l I I KW VV" c M i was um:

I V smumcgbuzmm g 4' HYDRAULIC.

mun RETURN INVliN'IUR. LEMUEL D-WOODDY,JR., HUBERT P. BEZNER,

ATTORNEY.

BACKGROUND OF THE INVENTION When drilling oil and/or gas wells from a floating vessel, it has been the practice to install a marine riser (steel pipe) to provide a return path for drilling fluids and formation cuttings and as means for guiding the drill bit into the well bore through the subsea blowout preventer. Normally, a slip joint" is included at the top of the marine riser to accommodate vessel motion. In relatively shallow water, the marine riser is sufficiently stiff to stand alone without the need for external tension. In deeper water, however, the longer marine riser becomes very limber and it has a tendency to buckle due to the various forces acting on it. In order to counteract these forces and thereby reduce the resulting stresses in the pipe, an axial load is applied at the top of the marine riser to maintain a predetermined level of tension. Current methods for applying this constant tension utilize either dead weight, counterweights or pneumatic cylinders. As the water depth increases, the amount of tension required for a given diameter marine riser also increases, which in turn requires larger tensioning systems. Limited deck space, handling difficulties, and high costs make a method for either eliminating or at least minimizing such high tension requirements highly desirable. One solution provided by the present invention involves eliminating the marine riser. If the marine riser is not required to permit the passage of drill strings, casing strings and ocean floor casing hangers internally, a simple mud return line having a considerably reduced diameter may be used. In this manner tension requirements are reduced and possibly even eliminated through the use of a neutrally buoyant flexible return line.

Drilling fluids or muds" normally used have a higher specific gravity than does sea water. If a mud return line is used through which the drill string is not run, a pressure differential is created at the point at which the drill string enters the subsea well-head (or subsea blowout preventer). This pressure differential is equal to the difference between the hydrostatic heads of mud column and sea water column. Equipment required for an arrangement of this type must:

I. Withstand the pressure differentials regardless of whether the drill string, casing string, etc. is in or out of the hole.

2. Permit the entry of various diameters of drilling equipment such as bits, stabilizers, drill collars, tool joints, etc., and simultaneously maintain a pressuretight seal.

3. Maintain a pressuretight seal while the drill string is rotating and/or reciprocating vertically.

4. Permit changing the packing element easily.

5. Be operated remotely from the drilling vessel.

SUMMARY OF THE INVENTION A remotely operated rotating wellhead for use in drilling subsea wells which includes a housing for connection to subsea equipment; a rotatable bearing element arranged in the housing; a sealing element attached to the bearing element and expandable by pressure to engage drill pipe or other tool against whichthe sealing element is to seal; bearings arranged between said bearing element and said housing; seal means arranged between said bearing element and said housing; a retainer plate for retaining said bearing element and sealing element within said housing. Hydraulic lines extending from the water surface may be connected to conduits within the housing and bearing element to supply fluid pressure within the sealing element to expand the element into sealing position or a passageway may be formed in the bearing element in communication with the well bore to permit well fluids to supply the pressure for inflating the sealing element. Lubrication lines are provided from the surface of the water to supply lubrication to the bearing surfaces between the bearing element and the housing. In addition, the retainer plate may be provided with a hydraulically operated latch mechanism. The hydraulic fluid for the latch mechanism is supplied from the surface of the water. Suitable guide means are provided to facilitate proper subsea positioning of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing the remotely operated rotating wellhead connected into an operable drilling system; and FIG. 2 is a partly sectional view showing the remotely operated rotating wellhead in greater detail.

DESCRIPTION OF THE PREFERRED EMBODIMENTS There is shown in FIG. 1 an arrangement of equipment for offshore drilling operations which includes a drill pipe 10 suspended from a floating drilling barge ll. Drill pipe 10 extends through subsea well apparatus which includes a rotating head 12, a flexible joint 13, a subsea connection 14, a BOP stack 15, a subsea connector 16 and a wellhead 17. The subsea well apparatus is lowered into position on guidelines 20 (other guide means could be used instead) which connect wellhead 17 to drilling barge 1 l. The subsea apparatus is provided with guide arms 21, connected to guide sleeves 22 through which the guidelines extend. A flexible mud return line 25 connects into the subsea apparatus below rotating head 12 and above flexible joint 13 and extends to the drilling barge l1. Rotating head 12 is provided with hydraulic lines 26 and 27 and a lubrication line 28, all of which extend to the drilling barge 11. Additional control lines, not shown, will be provided to control operation of the blowout preventers in the BOP stack 15 and in the subsea connectors 14 and 16.

For a more detailed description of rotating head 12, reference is made to FIG. 2. As shown in that figure, a sealing element 30, formed of resilient material similar to that used in bag-type blowout preventers fits inside of and is retained in and rotates with a bearing element 31 to which it is attached. Bearing element 31 is contained within a housing 32 and is covered by an upper retainer plate 33. A number of roller (and/or thrust) bearings 34 are arranged between the interior walls of housing 32 and bearing element 30 and retainer plate 33 is in contact with bearing element 31 by way of roller bearing 33a. A number of seals 35 are also arranged between the inner walls of housing 32 and retainer plate 33 and the outer walls of bearing element 31. A conduit 40 formed in bearing element 31 fluidly communicates the interior of sealing element 30 and a passageway 41 formed in the wall of housing 32 which in turn connects to hydraulic line 26. Another conduit or passageway 42 is formed in bearing element 31 and fluidly communicates the lower end of bearing element 31 exposed to well pressures and the interior of sealing element 30. Another passageway 43 formed in the wall of housing 32 connects to lubrication line 28 at one end and the space between the inner wall of housing 32 and the outer wall of bearing element 31. A hydraulically operated latch member 45 includes a hydraulically driven lug member 46 which is movable into and out of a recess 47 formed in retainer plate 33 and is supplied with hydraulic fluid through hydraulic line 27. A flange (or hub or other type connection) 50 formed in the lower end of housing 32 connects to mud return line 25.

In operation, wellhead 17 is lowered through the water from drilling barge I1 and secured to the land underlying the water, in accordance with conventional practice. Then, BOP stack 15, together with the subsea connector 16, subsea connector 14, flexible joint 13 and rotating head 12, including housing 32 and sealing element 30, bearing element 31 and retainer plate 33 are lowered on drill pipe 10 and guidelines 20 with the mud return line 25 connected to the subsea apparatus. Sealing of sealing element 30 against drill pipe 10 or other tool is achieved by exerting fluid pressure through hydraulic line 26 and passageways 41 and 40 or alternatively pressure from the well bore acting on sealing element 30 through passageway 42 may be used instead. Rotation of drill pipe 10, against which the sealing element 30 is sealed, rotates sealing element 30 and bearing element 31. Bearing surfaces between bearing element 31 and housing 32 are lubricated by a liquid similar to water soluble oil which'is supplied from drilling barge 11 through lubricating line 28 and passageway 43. The retaining gap 33 may be released by withdrawing lug 46 from recess 47 by hydraulic operation of the latch 45 through hydraulic lines 27 to permit replacing sealing element 30. Sealing element 30, bearing element 31 and retainer plate 33 are run and retrieved on drill pipe 10. When in subsea position, sealing element 30 permits passage of tool joints. Drill collars on drill pipe raise sealing element 30 and bearing element 31 out of housing 32 when coming out of the hold with drill pipe 10.

The rotating element may have grooves which spiral along its outer surface to carry away solids or other foreign material.

Having fully described the apparatus, operation, objects and advantages of our invention, we claim:

1. A remotely operated rotating wellhead comprising:

a housing connected to subsea equipment;

a rotatable bearing element arranged in said housing;

a fluid pressure expandable sealing element retained within and attached to said bearing element;

a releasable retainer plate arranged on top of said housing and said bearing element for retaining said bearing element within said housing;

remotely operated hydraulic means for releasing said retainer plate;

seal means arranged between the interior walls of said housing and said retainer plate and the exterior walls of said bearing element to close off the space therebetween;

bearing members permitting rotation of said bearing element and sealing element within said housing; and

means for supplying hydraulic fluid to the interior of said sealing element including a passageway fluidly communicating directly with well pressure and a passageway fluidly communicating with a source of fluid pressure exterior to said housing.

2. A rotating wellhead as recited in claim 1 in which said sealing element, bearing element and retainer plate are run and retrieved on drill pipe.

3. A rotating wellhead as recited in claim 1 in which said means permitting rotation of said sealing element and said bearing element within said housing includes roller bearings.

4. A rotating wellhead as recited in claim 3 including means arranged on said housing for cooperating with guide means extending from a floating vessel for guiding said housing into proper position on a subsea BOP stack.

Claims (4)

1. A remotely operated rotating wellhead comprising: a housing connected to subsea equipment; a rotatable bearing element arranged in said housing; a fluid pressure expandable sealing element retained within and attached to said bearing element; a releasable retainer plate arranged on top of said housing and said bearing element for retaining said bearing element within said housing; remotely operated hydraulic means for releasing said retainer plate; seal means arranged between the interior walls of said housing and said retainer plate and the exterior walls of said bearing element to close off the space therebetween; bearing members permitting rotation of said bearing element and sealing element within said housing; and means for supplying hydraulic fluid to the interior of said sealing element including a passageway fluidly communicating directly with well pressure and a passageway fluidly communicating with a source of fluid pressure exterior to said housing.

2. A rotating wellhead as recited in claim 1 in which said sealing element, bearing element and retainer plate are run and retrieved on drill pipe.

3. A rotating wellhead as recited in claim 1 in which said means permitting rotation of said sealing element and said bearing element within said housing includes roller bearings.

4. A rotating wellhead as recited in claim 3 including means arranged on said housing for cooperating with guide means extending from a floating vessel for guiding said housing into proper position on a subsea BOP stack.

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