US3168142A

US3168142A - Wellhead base assembly

Info

Publication number: US3168142A
Application number: US162828A
Authority: US
Inventors: Bruce J Watkins; Glenn D Johnson
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1961-12-28
Filing date: 1961-12-28
Publication date: 1965-02-02
Anticipated expiration: 1982-02-02
Also published as: GB957660A

Description

1965 B. J. WATKINS ETAL 3,168,142

WELLHEAD BASE ASSEMBLY Filed Dec. 28. 1961 z o o o o o :o 23

21 F 44 I I 4? I 33 340 Wi 1 n 4| 559 I I i1.v F 3 r18 K 34 I I 420 F 1% l5 mvemons:

' B. J. WATKINS G. D. JOHNSON BY. u (4,74 (1% T IR AGENT United States Patent 3,168,142 WELLHEAD BASE ASSEMBLY Bruce J. Watkins, West Covina, and Glenn D. Johnson, Downey, Calif., assignors to Shell Oil Company, New York, N .Y., a corporation of Delaware Filed Dec. 28, 1961, Ser. No. 162,828 7 Claims. (Cl. 16666.5)

This invention relates to the drilling, completion and working over of oil and gas wells, and pertains more particularly to apparatus whereby certain equipment used in well operations may be positioned for movement around a wellhead assembly that is positioned on the ocean floor or a considerable distance below the surface of a body of water.

In an attempt to locate new oil fields, an increasing amount of well drilling has been conducted at offshore locations, such, for example, as off the coast of Louisiana, Texas and California. As a general rule, the strings of casing in a well together with the tubing string or strings, extend to a point well above the surface of the water where they are closed in a conventional manner that is used on land wells, with the conventional wellhead assembly being attached to the top of the casing. Since the wellhead assembly is above the surface of the water, all connections and adjustments to equipment thereon are made manually. Methods have recently been developed for drilling and working on wells at offshore locations where the water depth is greater than that at which divers can readily operate. One such method and the apparatus used in the method is described in copending patent application Serial Number 118,949, filed June 22, 1961.

The method described in the above-identified copending patent application utilizes a remotely operable manipulator device adapted to be positioned on an underwater wellhead for making any necessary connections or adjustments of equipment thereto. Well drilling completion or work-over operations are carried out from a platform positioned above the surface of the body of water, the platform preferably being in the form of an operating platform of a vessel such as a well-drilling barge. Since any vessel on the surface of the ocean is subjected to considerable vertical motion, it is not possible to suspend therefrom a manipulator device which could be used to make the necessary connection to a wellhead during well drilling operations.

It is therefore an object of the present invention to provide an operating base assembly adapted to be positioned on a well casing of an underwater well whereby a manipulator device may be fixedly positioned relative to the wellhead or well casing against normal vertical movement.

A further object of the present invention is to provide an operating base assembly adapted to be removably positioned on a vertically extending underwater well casing and providing track means whereby a manipulator device may be seated thereon for movement around the well.

Another object of the present invention is to provide an operating base assembly adapted to be removably positioned on a well casing of an underwater well and fixedly secured to a wellhead assembly for removal therewith.

These and other objects of the present invention will be understood from the following description taken with reference to the drawing which illustrates a longitudinal view taken partly in cross-section of an underwater well.

Referring to the drawing, an underwater wellhead assembly is shown as being positioned adjacent to the ocean floor 11 and comprises concentric strings of

casing

12, 13, 14, 15 together with an inner production tubing 16. The

outermost casing strings

12 and 13 may be arranged in a manner illustrated to form a double-wall conductor pipe 3,168,142 Patented Feb. 2, 1965 "ice wherein the annulus 17 between the

casings

12 and 13 may be filled with cement to give added rigidity to the structure. The casing string 14 may be a surface casing whose upper end is screw-threaded to a casinghead 18. Upper and

lower portions

20 and 21, respectively, of a production wellhead assembly are illustrated as being positioned at the top of the casinghead 18. The upper portion of the production wellhead assembly or the production bonnet 20 is secured by suitable horizontally extending bolts 22 to an upwardly extending portion of the lower portion 21 of the production wellhead. In a like manner the lower portion 21 of the production wellhead is fixedly secured to the casinghead 18 by bolts similar to bolt 22. A bolt similar to bolt 22 would be positioned in each of the holes 23 in the upper and lower portions of the production wellhead.

The production wellhead assembly is also provided with a plurality of inwardly extending locking bolts 24 each of which is positioned in the series of holes (similar to holes 23 which receive bolts 22, but at the level of bolts 24) and extend inwardly to engage and hold down casing or tubing hangers (not shown). Since, the details of the production wellhead assembly represented by

portions

20 and 21 do not form a part of the present invention they will not be further described in detail here. It is to be understood that the wellhead assembly could be a drilling wellhead assembly as well as a production wellhead assembly. The production wellhead assembly is preferably provided with a pair of

guard rings

26 and 27 which protect the bolts on the wellhead against damage. One of the

guard rings

26 and 27 may be provided with a circumferential groove 28 or other indexing means for fixedly positioning the base assembly of the present invention to the production wellhead.

The top of the conductor pipe formed by the

casing strings

12 and 13 may be closed in any suitable manner, as by a closure member 30 which extends downwardly between the two

casings

12 and 13 and is provided with a seal 31 for sealing against the casing string 14. The seal 31 is held in place by a follower ring or bushing 32. The casinghead 18 may be provided with a support base 35 adapted to seat on the closure member 30 at the top of the conductor pipe. The top of the conductor pipe and/ or its closure member 30 is provided with a landing shoulder 34 which is preferably beveled downwardly and out wardly so that foreign material does not accumulate at an underwater location.

The wellhead or operating base assembly of the present invention is represented generally by numeral 35 and comprises a tubular housing member 36 of a diameter slightly larger than the outermost casing string 12 of the well which extends up to the casinghead 18. The downwardly extending lower portion 37 of the housing member 36 forms stabilizer means for the housing member and isof a length sufiicient to prevent the housing member from being tilted off the top of the casing string 12 when objects of substantial weight are hung on one side of the base assembly 35.

The lower portion of stabilizing member 37 of the housing member 36 is slightly larger in diameter internally than the external diameter of the well casing 12 which is to be received therein. Preferably, a series of spacer blocks 38 are integrally formed on or fixedly secured to the inner wall of the stabilizer portion 37, or to the outer wall of the upper end of the casing string 12, so as to reduce the frictional contact area between the base asssembly 35 and the casing string 12. The use of spacer blocks 38 is not essential in which case the stabilizer portion 37 would directly contact the casing string 12. While the stabilizer portion 37 of the housing member 36 has been shown as a downwardly extending tubular member, it is to be understood that the stabilizer portion may take form of a downwardly extending series of supporting arm ole-- merits. To facilitate the placement of the base assembly 35 in telescopic arrangement on the top of the well casing 12, the lower end of the stabilizer portion 37 of the base assembly is preferably provided with aligning means which may be in the form of an outwardly flaring skirt A landing shoulder 41 is fixedly secured to 'or formed on the inner wall of the housing member 36 and preferably extends therearound the internal periphery thereof. The landing shoulder 41 is of a diameter and shape to seat on the cooperating landing shoulder 34a on base plate 39 at bottom of ribs 33 attached to wellhead portion 21.

Fixedly secured to the outer surface of the housing member 36 intermediate the ends thereof and disposed outwardly therefrom is a circular track 42 which extends peripherally the entire distance around the housing mern ber 36. It is to be realized that on some wellhead installations, all of the mechanically actuated elements, connections or adjustments may be positioned on one side of the production head so that it would not be necessary to have the track 42 extend all the way around. In such a case it would be sufficient to have a track extend over only a portion of the housing member 36. The track 42 is fixedly mounted to the housing member 36 as by being welded to suitable support brackets 43. Although the track 42 is shown as being in the form of an upwardly extending section 42a on which wheels of a manipulator device or other underwater device (not shown) may travel, the track may take any form in cross-sectional area. Preferably, the space between the track 42a and the housing member 36 is not provided with a horizontal removed or stripped upwardly over the production wellhead 20-21 without removing the latter from the well. The removable operating base assembly 35 of the present invention provides removable track means by which an underwater manipulator device (not shown) may be positioned on, hung from and/or travel around a wellhead to carry out any desired number of operations with the control of the manipulator being carried out from a remote location.

In the preferred form of the invention, the landing shoulder 41 is supported on landing surface 34a of base plate 39; The plate 39 isin turn attached tosupport brackets 33 which are secured to the lower portion 21 of the wellhead assembly which is fixedly mounted on the top of casing 14. Beingso arranged the wellhead track base assembly is always in fixed relation with the wellhead assembly 20-21 regardless of possible relative movement of casing 14 to

casings

12 or 13.

It is to be understood that the arm elements 44 are positioned in a manner such that there is always. free access to the screws 22' and 24 along the axis thereof. One form of an orienting device may be dimples or recesses 49 in the groove 28 of a size to receive the coneplate at the bottom of the track, thus permitting solid I matter, sand or sediment at an underwater location from settling in and filling the space between the track 42a and the housing member 36. However, in some installations it may be preferred to put a bottom plate. on the track so to allow wheels torun on the bottom plate while the upright portion 42a prevents the wheels from falling, oif the track. Additionally, the track 42a in cross-section could extend downwardly below the brackets 43 so as to permit clamping devices to ride underneath the track while wheels are running on top or within the track. The track 42a in cross-section may take any suitable form depending upon the type of wheels intended to cooperate with it.

The housing member 36 is provided with a plurality of upwardly extending arm elements 44 which 'are preferably secured together by means 'of reinforcing rings or

bands

46 and 47 which are of a diameter slightly larger than the guard rings 26 and 27, respectively, mounted on the production wellhead 20-21. The upper ends of thearrns 44 or the reinforcing ring 46 are providediwith a suitable connector device, preferably in the form of horizontally extending bolts 48 which can be screwed inwardly to engage and seat in the peripheral groove 28 in the guard ring 26, or may be fixedly secured to another portion of the production wellhead assembly 20-21.

In using the operating base assembly '35 of the present invention, it may be secured bymeans of the bolts 48 to the production wellhead assembly 20-21 on a drilling barge above the surface of the water and subsequently lowered into place together with the production wellhead when the latter is lowered through the water and positioned on top of the conductor pipe formed by the well casing strings 12 and 13. 7

Subsequently, the operating base assembly of the present invention may be removed together with the pro-' duction wellhead sections 20 and/or 21 or the bolt :48 may be unscrewed to release it from the production wellhead so that the production wellhead sections 20 and/ or 21 may be retrieved from the ocean floor while the operating base assembly 35 remains in place. The internal dimensions of the operating base assembly 35 are preferably such that it could be independently pointed ends of at least one screw 48. The orientation of the dimples 49 with respect to the control screws 22 and 24 is such that when the dimples 49 are engaged by the screws'48 the arms 44 are not axially aligned with any screw '22 or 24. In operation, the assembly 35 may first be attached to the production bonnet or wellhead section 20 by means of screws 48 which engage dimples: 49. The entire assembly is then lowered along with casing 14 to the positionillustrated.

In subsequent operations, should the assembly 35 be removed from the well with the upper portion 20 ofthe' production wellhead assembly, the screw 48 and dimple 49' arrangement is re-established before lowering the astion of the arms 44. 7

We claim as our invention:

1. An operating base assembly adapted to be removably positioned on at least a portion of a wellhead assembly extending upwardly from an underwater well, said base assembly comprising I,

(a) a housing member having an opening extending vertically therethrough,

(b) stabilizer means for said base assembly carried by said housing member and adapted to engage the outer surface of a portion of 'said wellhead assembly,

(a) shoulder means carried on the inner wall of said housing member for seatingon said wellhead assembly, and

(d) track means fixedlysecured to said housing memher and disposed radially outwardly therefrom, said traclcmeans having a smooth uninterrupted upper surface extending entirely around said housing memher.

2. An operating base assembly adapted to be removably positioned on a wellhead assembly extending upwardly from an underwater well, said base assembly cornprising 7 7 (a) a housing member. having an opening extending,

vertically therethrough,

(b) stabilizer means for said base assembly formed by' a portion of said housing member and adapted toengage the outer surface of a portion of said wellhead assembly,

' (1) said lower portion of said base assembly being of an internal diameter. substantially equal to but larger than the external diameter of said portion of said wellhead assembly to be received therein, p

(c) shoulder means carried on the inner wall of said housing member for seating on said wellhead assembly, said shoulder means being carried at the top of said housing member,

(d) track means fixedly secured to said housing memher and horizontally disposed radially outwardly therefrom, and

(e) releasable connector means carried by said housing member above said shoulder means thereof for engaging said wellhead assembly adapted to be positioned within said housing member.

3. The apparatus of claim 2 wherein said track means extends a substantial way around the periphery of said housing member.

4. The apparatus of claim 2 wherein said connector means comprises inwardly-extending releasably-engageable connector elements.

5. The apparatus of claim 4 wherein the connector elements are screw-threaded bolts.

6. The apparatus of claim 2 including aligning means carried on the lower end of said stabilizing means for centralizing the housing member as it is lowered on the top of said portion of said wellhead assembly.

7. An operating base assembly adapted to be removably positioned on the top of a large diameter pipe string extending upwardly from an underwater well, said base assembly comprising (a) a housing member having an opening extending vertically therethrough,

(b) stabilizer means for said base assembly formed by the lower portion of said housing member with the top of a portion of said wellhead assembly,

(1) said lower portion of said base assembly being of an internal diameter substantially equal but larger than the external diameter of said portion of said wellhead assembly to be received therein,

(0) shoulder means carried on the inner Wall of said housing member for seating on said portion of said Wellhead assembly, said shoulder means being car ried at the top of said housing member,

(0.) track means fixedly secured to said housing member intermediate the ends thereof and disposed radially outwardly therefrom,

(1) said track means extending a substantial way around the periphery of said housing member,

(e) connector means carried by said housing member above said shoulder means thereof for engaging a wellhead adapted to be positioned within said housing member,

(1) said connector means including inwardlyextending releasably-engageable connector elements,

(f) and aligning means carried on the lower end of said stabilizing means for centralizing the housing member as it is lowered on the top of said pipe string.

References Cited by the Examiner UNITED STATES PATENTS 2,237,683 4/41 Minor 16685 2,661,063 12/53 Owens 16685 XR 3,020,956 2/62 Suderow l6666.5 3,021,909 2/62 Postlewaite 166-46 XR 3,071,188 1/63 Raulins 166-665 CHARLES E. OCONNELL, Primary Examiner.

Claims

1. AN OPERATING BASE ASSEMBLY ADATPED TO BE REMOVABLY POSITIONED ON AT LEAST A PORTION OF A WELLHEAD ASSEMBLY EXTENDING UPWARDLY FROM AN UNDERWATER WELL, SAID BASE ASSEMBLY COMPRISING (A) A HOUSING MEMBER HAVING AN OPENING EXTENDING VERTICALLY THERETHROUGH, (B) STABILIZER MEANS FOR SAID BASE ASSEMBLY CARRIED BY SAID HOUSING MEMBER AND ADAPTED TO ENGAGE THE OUTER SURFACE OF A PORTION OF SAID WELLHEAD ASSEMBLY, (C) SHOULDER MEANS CARRIED ON THE INNER WALL OF SAID HOUSING MEMBER FOR SEATING ON SAID WELLHEAD ASSEMBLY, AND (D) TRACK MEANS FIXEDLY SECURED TO SAID HOUSING MEMBER AND DISPOSED RADIALLY OUTWARDLY THEREFROM, SAID TRACK MEANS HAVING A SMOOTH UNINTERRUPTED UPPER SURFACE EXTENDING ENTIRELY AROUND SAID HOUSING MEMBER.