US3516492A - Underwater wellhead connector - Google Patents

Description

June 23, 1970 E w. H. PETERSEN 3,516,492

UNDERWATER WELLHEAD CONNECTOR Filed May 23, 1968 v 2 Sheets-Sheet 1 Y /V/Y INVENTOR:

WILLIAM H. PETERSEN aw 4 v HIS ATTORNEY Jun 3, 1970 w. E. PETERSEN 3,516,492

UNDERWATER WELLHEAD CONNECTOR Filed May 23. 1968 2 Sheets-Sheet 2 nfil 55 K 5? WI 67 ll n ll FIG. 2

INVENTOR WILLIAM H. PETERSEN HIS ATTORNEY United States Patent 3,516,492 UNDERWATER WELLHEAD CONNECTOR William H. Petersen, Houston, Tex., assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed May 23, 1968, Ser. No. 731,381 Int. Cl. E21b 43/ 0] F161 39/00 US. Cl. 166-.6 4 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to oil well equipment for use at underwater locations. More particularly, the invention relates to a wellhead connector which may be used to establish operative communication between a vessel floating on the surface of a body of water and a wellhead assembly or production control unit of an underwater well whereby maintenance or other operations with respect to the well and/or wellhead assembly may be carried out from the vessel.

A recent development in the field of oil well drilling is the completion of wells at offshore locations with a wellhead assembly positioned on or close to the ocean floor out of the way of ships which might otherwise damage it in the event of collision. Equipment placed on the ocean floor, however, is exposed to conditions such as the corrosive nature of the sea water and the presence of marine life which tends to grow and become encrusted on metallic structures below the surface of the water.

It is necessary therefore from time to time to go back into a well wherever it has been completed for well servicing or work-over operations. In addition, the underwater wellhead assembly itself may call for periodic repair and maintenance. Accordingly, it is desirable to have an underwater wellhead assembly of suitable design so that it may be readily removed from the underwater wellhead and raised to the surface. It is also desirable to have a wellhead assembly of a construction which will permit work-over operations in the well from the vessel through the assembly. One underwater wellhead assembly permitting both of these operations as desired is disclosed in US. Pat. No. 3,064,734, issued Nov. 20, 1962, to R. J. Bauer et al.

In accordance with present practice, maintenance or other undersea operations with respect to a producing well are usually initiated by establishing guide means, such as guidelines, between the vessel and the well site. A suitable wellhead connector device is then normally lowered by means of a pipe string along the guide means to the wellhead assembly whereupon the desired operations are performed from the vessel. Some operations may be performed with the wellhead assembly remaining in place but occasionally it may be necessary to disconnect the wellhead assembly from the underwater wellhead and production flow lines and pull it up to the vessel by means of the pipe string along the guide means.

Time is an important consideration in offshore oil well operations due to the large per diem expenses involved in the rental of barge equipment, wages, etc. Then too,

3,516,492 Patented June 23,, 1970 prolonged well shut-down for maintenance is costly due to lost oil production. Accordingly, it is advantageous to perform all operations relating to an undersea well, including maintenance and work-over operations, as quickly as possible.

SUMMARY OF THE INVENTION It is therefore a primary object of the present invention to provide a wellhead connector which can be lowered from a floating vessel and positioned on an underwater wellhead assembly without the necessity of first establishing guide means between the vessel and the wellhead site.

A further object of the present invention is to provide a wellhead connector incorporating wellhead assembly locating and positioning means for assisting the operator in locating the wellhead assembly and operatively positioning the connector with respect to the wellhead assembly.

These objects have been attained in the present invention by providing a wellhead connector lowerable from a floating vessel which incorporates sonar and TV equipment for assisting in the positioning thereof on an underwater wellhead assembly. After the connector is locked into engagement with the assembly by suitable latch means, an inner conduit assembly incorporated in the wellhead connector is moved by prime mover means into operative association with production tubing extending into the well. Since the inner conduit assembly is also in continuous fluid communication with one or more tubing strings extending to the vessel, desired operations may be carried out from the vessel with respect to the well and/ or wellhead assembly.

DESCRIPTION OF THE DRAWING These and other objects of this invention will be understood from the following description taken with reference to the drawings wherein:

FIG. 1 is a diagrammatic view illustrating a barge or vessel floating on the surface of a body of water over an underwater wellhead assembly, the vessel having depending therefrom the wellhead connector according to the present invention;

FIG. 2 is a longitudinal view taken in partial crosssection illustrating the wellhead connector according to the present invention in operative engagement with an underwater wellhead assembly; and

FIG. 3 is an enlarged, partial cross-sectional view illustrating a portion of the wellhead connector according to the present invention in association with a cooperating portion of an underwater wellhead assembly.

Referring to FIG. 1 of the drawing, a drilling vessel or barge 11 of any suitable floatable type is illustrated as floating on the surface of a body of water 12 and substantially fixedly positioned over a preselected location by suitable barge positioning means or by being anchored to the ocean floor 13 by suitable anchors (not shown) connected to anchor lines 14 and 15. Equipment of this type may be used when carrying on operations in water depths varying from about to 1500 feet or more. The drilling barge is equipped with a suitable derrick 16 as well as other auxiliary equipment needed during well work-over or maintenance operations. The derrick 16 is positioned over a drilling slot 17 which extends vertically through the barge in a conventional manner. When using the equipment according to the present invention, the slot of vessel 11 may be either centrally located or extend in from one edge thereof. However, operations may be carried out over the side of the barge or vessel without the use of a slot.

' An underwater wellhead structure is illustrated in FIG. 1 as comprising a base member 18 which is positioned on the ocean floor 13 and is fixedly secured to a large diameter well casing 19 which extends down into a well, which has been previously drilled, and is preferably cemented therein. One or more strings of production tubing such as tubing strings 20 and 21 are suspended within the well casing and extend into the well in the usual manner. If desired, the wellhead structure may include two or more vertical guide columns 22 and 23 adapted to cooperate with guide lines extending downwardly from vessel 11 in the manner which is more clearly set forth in copending US. patent application Ser. No. 731,382, filed May 23, 1968.

Positioned on base member 18 is a casinghead unit 24 with a wellhead assembly or production control unit 25 attached thereto. Normally, the production control unit or wellhead assembly is in fluid communication with the production tubing and comprises the necessary piping, valves, chokes, and other equipment normally connected together and mounted on the top of a well, and known as a Christmas tree, together with the necessary hydraulic or electrical systems, including pumps, reservoirs, motors, etc., to operate the valves at the head of the well from a remote location. A typical example of a suitable underwater production control unit or wellhead assembly for use at an offshore well location, and its manner of operation, is shown and described in U.S. Pat. No. 3,064,- 735, issued Nov. 20, 1962, to R. J. Bauer et al. For purposes of illustration, it will be assumed that the wellhead assembly utilized in conjunction with the present invention will be similar to that described in the above patent, although it is of course obvious that the wellhead connector according to the present invention could be used with other suitable wellhead assembly designs.

Wellhead 25 includes one or more fluid flow handling conduits, such as conduits 26 and 27, and an upstanding wellhead entry conduit 28. Fluid flow handling conduits 26 and 27 communicate with production tubing strings 20 and 21, respectively, and are smoothly curved in an are which would permit objects, such as through-the-flowline tools to be circulated therethrough into the well.

Depending from drilling platform 11 by means of a pipe string 29 is the wellhead connector 30 according to the present invention. If desired, connector 30 may have operatively associated therewith guideline carrying means 31 and 32 and guidelines 33 and 34 depending from Vessel 11. It is to be understood that upon the eventual lowering of guideline carrying means 31 and 32 into communication with guide columns 22 and 23 the guidelines would be connected thereto in some suitable manner. However, columns 22 and 23, guide line carrying means 31 and 32, and guidelines 33 and 34, form no part of the present invention and are shown here for purposes of illustration only. The wellhead connector 30 could be suitably used without a guideline arrangement if desired.

Referring now to FIG. 2, wellhead connector 30 includes a cylindrical body member 35 defining a throughbore 36 into which extends tubing runs 37 and 38. Tubing runs 37 and 38 extend upwardly within pipe string 29 to vessel 11. Preferably, the tubing runs 37 and 38 are each comprised of individual tubing sections of substantially the same length as the sections of pipe comprising pipe string 29 and are integrally attached thereto by suitable internal frame means to form integral units. An arrangement of this type is disclosed in copending US. application No. 690,996, filed Dec. 15, 1967. However, the tubing runs may be independently disposedwithin pipe string 29 if so desired.

A framework 39 is attached to the lower end of body member 35 and extends outwardly therefrom in the manner shown. The framework 39 carries wellhead assembly locating means and positioning means for assisting the operator on vessel 11 in locating wellhead assembly 25 and operatively positioning connector 30 thereon. These operations will be explained in more detail below. It should be noted at this point, however, that the locating and positioning means illustrated include a hydraulically A, actuated, extensible sonar unit 40 and a television camera 41 both of which may be utilized to monitor operations at the well site. A lamp unit 42 is affixed to television camera 41 to provide sufficient illumination during the course of the underwater operations. The camera 41 may be fixedly mounted but it is preferred that it be movably mounted for positioning at the will of the operator to provide greater flexibility with respect to what may be observed during the course of operations. Since television cameras and sonar units used for the purpose described are familitar to those skilled in the art and are set forth in patent and other literature, a detailed description of the operation thereof is not believed necessary. Also attached to the lower end of body portion 34 is a downwardly extending cone-shaped element 43 having a cutout portion 44 which is positioned to permit the camera to view operations taking place within the confines of the cone-shaped element 43. Cone-shaped element 43 also assists in the positioning of connector 30 onto the well head assembly as described below.

Body member 35 includes an inner cylindrically-shaped body member portion 45 which is mounted for downwardly extensible axial movement with respect to the rest of the body member. The body member portion 45 is normally biased by any suitable means, such as spring means (not shown), into a retracted first position. A flange member 46 is an integral part of body member portion 45 and a resilient O-ring member 47 is accom modated thereby which sealingly engages inner wall 48 of body member 35 thereby defining chamber 49 which is the annular space between body member portion 45 and the remainder of body member 35. A plurality of accumulators 50 are fixedly disposed about body member 35 and are attached thereto by any desired means. Conduits 51 provide fluid communication between accumulators 50 and chamber 49 with suitable valve means (not shown) being disposed within conduits 51 to establish or break the fluid communication between the accumulators 50 and chamber 49 as desired. The actuation of these valves Would be accomplished remotely from vessel 11 in the well-known manner. In the illustrated embodiment of the invention cable 52 including a plurality of electrical and/ or hydraulic conduits 53 is shown for conducting energy pulses from vessel 11 to the various valves, latches, etc. employed in wellhead connector'30. Valves referred to herein may be either electrically, pneumati cally or hydraulically actuated as desired.

The operation of the wellhead connector according to the present invention will now be described with greater particularity. It will be assumed that vessel 11 has been positioned over the approximate location of the wellhead assembly 25 upon which the desired operations are to be performed. The most usual method for accomplishing this is by surveying in on the known site of the well by suitable instruments aboard the vessel. As soon as the well location has been surveyed in and the vessel suitably positioned by anchor or other means, wellhead connector 30 is attached to pipe string 29 by any known coupling means and lowered from the vessel by adding additional sections of pipe to the string in the customary manner. This operation continues until it is determined that sufficient pipe sections have been added to position the connector at a distance from the ocean floor 13 somewhat greater than the height of wellhead assembly 25.

At this point the sonar unit 40 and the television camera 41 (as well as light 42) are actuated and monitored from vessel 11. The pipe string 29 and wellhead connector 30 are then manipulated from the vessel to position them in axial alignment with wellhead entry conduit 28. Additional pipe sections are then connected to the top of the pipe string 29 to lower connector 30 into engagement with wellhead entry conduit 28. The cone-shaped element 43 will act to axially align connector 30 with respect to conduit 28 as it is lowered thereon and television camera 41 with its unobstructed view through cut-out portion 44 will permit the operator on vessel 11 to view the operation. The lowering of connector 30 over wellhead entry conduit 28 continues until the top of conduit 28 firmly seats against the bottom of stop means 54 which comprises a shoulder section of the body member wall and extends into chamber 49 as shown in FIG. 2.

As may also be seen with reference to FIG. 2, an annular groove 55 is formed about the periphery of wellhead entry conduit 28. Upon the seating of the top of conduit 28 against stop means 54, hydraulically operated latch members 56 and 57, which are associated with suitable housings attached to body member 35, are actuated and position themselves in groove 55 in the manner shown. It is, of course, obvious that suitable conventional hydraulic lines and hydraulic pressure source means are provided to actuate the latch members, but these elements have not been shown for purposes of clarity. The latch members 56 and 57 may be actuated either automatically upon the seating of the conduit 28 against stop means 54 or by an operator on vessel 11. Latch locking means 8 and 59, also hydraulically operated, are actuated after latch members 56 and 57 are in operative association with groove 55. Latch locking means 58 and 59, also hydraulically operated, are actuated after latch members 56 and 57 are in operative association with groove 55. Latch locking means 58 and 59 serve to lock the latch members 56 and 57 into engagement with groove 55 in the manner shown in FIG. 2. Once again, for the purpose of clarity, the complete hydraulic system for operating latch locking means 58 and 59 has not been shown. If desired, the latch locking means may be actuated at the will of an operator on vessel 11 or automatically upon the positioning of latch members 56 and 57 in groove 55.

Referring now to FIG. 3, the respective relative positions of body member portion 45 and wellhead entry conduit 28 are shown just after the above-described latching operation has been completed. Body member portion 45 is in its retracted first position. It is also assumed that wellhead connector 30 has been properly rotatably aligned with respect to entry conduit 28 to the position illustrated. This may be done either by manipulating pipe string 29 and connector 30 from vessel 11 with reference to the image transmitted by television camera 41 or by providing suitable cooperating aligning means on the connector and entry conduit. Aligning means of this type is disclosed in copending US. application Ser. No. 731,382 filed May 23, 196 8. Attached to body member portion 45 by any suitable means, such as by welding, is an inner conduit assembly means comprising plate means 60 and tubing runs 37 and 38. The assembly means further includes locking plate means 61 which is secured to plate means 60 by means of screws 62 and 63. The tubing runs 37 and 38 extend through axially aligned apertures in plate means 60 and locking plate means 61 and are fixedly secured in the position illustrated by any suitable means. For example, the tubing runs may be welded onto locking plate means 61 or may be press fit into the associated apertures of locking plate means 61. Other pipe members for effecting various well operations, such as tubing member 64, may also be disposed in body member portion 45 and extend through plate means 60 and locking plate means 61. The end of tubing member 64 which has not been illustrated would be operatively connected to a suitable power source such as one of the conduits 53. Tubing runs 37 and 38 and tubing member 64 preferably incorporate recessed ends 65, 66 and 67, respectively, with sealing elements disposed thereon in the manner shown. if desired, electrical cables to effect various operations on the wellhead could also be disposed in body member portion 45 and extend to plate means 60. Any such electrical cables would be equipped with termination fittings of any suitable design and attached to plate 61. Since electrical cables and connectors of any suitable type well known in the art may be used in this purpose it is not deemed necessary to describe such an arrangement further.

A support plate 68 is disposed in wellhead entry conduit 28 as is also shown in FIG. 3. Fixedly positioned in support plate 68 by means of any known expedient are connector elements 69 and 70 and tubing member coupling element 71 all of which comprise cylindrical pipes. The connector elements 69 and 70 extend downwardly into the wellhead assembly and are in axial alignment and fluid communication with production tubing strings 20 and 21. In the event electrical termination fittings and electrical cable means are operatively associated with the plate means 61 mating electrical fittings or plugs of any suitable design would be provided on support plate 68 with cooperating cable means (not shown) extending into the assembly. During the actual well production operation valve means (not shown) interrupts the fluid communication between tubing strings 20 and 21 and their respective connector elements 69 and 70. US. Pat. No. 3,064,735 may be referred to for a more detailed description of an arrangement of this type. Tubing member coupling element 71 is in operative communication with one or more valve elements, latches, etc. (not shown) within the assembly or the well itself and which are elfective to shut down the well or perform other desired operations. Alternatively, the above-described electrical cables and connectors which may be employed could be used for this purpose. Since the precise nature of the operations to be performed vary according to the design of the particular wellhead assembly employed and the exigencies of the desired operation, no attempt has been made to describe this feature in greater detail. The connector according to the present invention could, of course be utilized with various numbers and sizes of pipes and/ or electrical cables as desired.

After the wellhead connector 30 has been latched into position on wellhead entry conduit 28 and the connector 30 has been rotated so that the body member portion 45 is aligned with respect to wellhead entry conduit 28 as shown in FIG. 3, the valve means (not shown) in conduits 51 (FIG. 2) are opened thereby building up hydraulic pressure in chamber 49 by flowing hydraulic fluid from accumulators 50. Rather than using the disclosed accumulators to provide the source of hydraulic fluid a direct operating hydraulic circuit could be established between one of the hydraulic conduits 53 and chamber 49 with hydraulic fluid pressure being furnished directly from vessel 11. By acting upon flange member 46 the hydraulic pressure within chamber 49 serves to force body member portion 45 and pipe string 29 in a downward direction so that all elements of wellhead connector 30 including tubing runs 37 and 38 and tubing member 64 are positioned as shown in FIG. 2. Body member portion 45 is now in its extended second position. After the pull-down operation has taken place, a hydraulically operated latch 72 is actuated to cooperate with a flange member 73 which is fixedly disposed about the periphery of body member portion 45. Latch 72 serves to lock tubing runs 37 and 38 and tubing member 64 into fluid-tight engagement with their respective cooperating connector elements 69 and 70 and tubing member coupling element 71. In like manner, any mating electrical connectors employed on plate means '61 and support plate 68 would be brought into engagement.

After the wellhead connector 30 has been connected as shown in FIG. 2, the desired operations may be performed. For example, tools or instruments may be cir culated down the well through the tubing runs 37 and 38, through connector elements 69 and 70, and into production tubing strings 20 and 21. The procedure for circulating tools and instruments through a wellhead assembly of this type, i.e., a Y-branched wellhead assembly, is more clearly set forth in the above-noted U.S. Pat. No. 3,064,- 735. If desired, suitable manipulations may be carried out through tubing runs 37 and 38 to close down the well and remove all or a portion of the Wellhead assembly 25 to the surface by pulling the pipe string 29 thereby permit- 7 ting suitable maintenance or other operations to be performed on the vessel. US Pat. No. 3,064,735 also describes an arrangement for effecting the removal of a wellhead assembly to the surface of a body of water for this purpose.

While this invention has been described with particular reference to a preferred embodiment thereof it should be understood that the form illustrated herein has been selected to facilitate the disclosure of the invention rather than to limit the number of forms which it may assume, and various modifications, adaptations and alterations may be applied to the form shown to meet the requirements of practice without departing from the spirit or scope of the present invention.

I claim as my invention:

1. A wellhead connector lowerable to an underwater wellhead assembly by means of a pipe string extending from a vessel floating on the surface of a body of water, said underwater wellhead assembly including an upstanding member having fluid conduit means herein, said connector comprising:

a body member having a vertical throughbore and being positionable over said upstanding member by said pipe string;

latch means carried by at least one of said members for effecting attachment therebetween;

a portion of said body member surrounding said throughbore being mounted for downwardly extensible axial movement with respect to the rest of said body member;

inner conduit assembly means carried by said body member portion for movement from a first position to a second position;

prime mover means carried by said body member and operatively engaging said body member portion for moving the inner conduit assembly means from said first position to said second position; and

cooperating means on said fluid conduit means of said wellhead assembly and said inner conduit assembly means for establishing fluid-tight communication therebetween upon movement of said inner conduit 8 assembly means from said first position to said second position;

said inner conduit assembly means comprising substantially rigid tube means fixedly positioned in plate means mounted at one end of said body member portion, said plate means having aperture means therein through which the tube means protrudes.

2. The connector according to claim 1, wherein a framework extends outwardly from said body member, said framework carrying wellhead assembly locating means and positioning means for assisting the operator in locating the wellhead assembly and operatively posititoning the connector with respect to the wellhead assembly.

3. The connector according to claim 1 wherein said prime mover means comprises a hydraulically actuated piston operatively associated with accumulator means mounted on said pipe string.

4. The connector according to claim 1 wherein said inner conduit assembly means is of a size to permit downward extension thereof into said upstanding member fluid conduit means of said wellhead assembly, said fluid conduit means being recessed downwardly from the top of said upstanding member.

References Cited UNITED STATES PATENTS 3,052,299 9/ 1962 Geer et a1. 166-.6 3,071,188 1/1963 Raulins 166.6 3,217,805 11/1965 Howard 166-.6 3,265,130 9/1966 Watkins 166-.6 3,301,322 1/1967 Newsome 166-.6 3,332,484 7/1967 Watkins 166.6 3,339,632 9/1967 Lewis 166.6 3,419,071 12/1968 Williams 166-.6

NILE C. BYERS, 111., Primary Examiner R. E. FAVREAU, Assistant Examiner U.S. C1. X.R. 285-26, 137

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