US3438653A - Wellhead - Google Patents

Description

April 15, 1969 J. H. FOWLER 3,438,653

WELLHEAD Filed,0ct.l4. 1966 Sheet of2 I N VENTOR.

fa/m H. Fowler p l 1969' I J. H. FOWLER 3,438,653

' WELLHEAD Filed on. 14, 19 66 Sheet 3 of 2 To/In H. Few/er INVENTOR.

United States Patent U.S. Cl. 285-133 Claims ABSTRACT OF THE DISCLOSURE An underwater wellhead with retractable hanger support shoulder. The support shoulder comprises several segments which when projecting radially inward of the bore of the wellhead provide a substantially 360 upwardly facing frustoconieal support for a pipe hanger. Each segment also has a downwardly facing frusto-conical surface which rests on an upwardly facing frustoconical surface of a recess encircling the wellhead. Each segment is connected by a rod to a piston which moves in a hydraulic cylinder in the'wellhead. When pressured from one end of the cylinder the piston and rod move each segment along the recess surface radially inward until the substantially continuous support shoulder is formed. When pressured from the other end of the cylinder the piston and rod move each segment along the recess surface radially outward until each segment is completely retracted within the recess leaving the well bore free of any projections. To permit fluid passage around the shoulder in its inward position passages are provided in the wellhead walls or through the segments This invention is related to pipe suspension apparatus and more particularly to means for suspending casing or tubing in underwater oil and gas wells.

The increased activity in underwater drilling for petroleum has brought about many new ideas in the industry. One of these is the extended casing method of drilling and completing a well. In such a method, the various wellhead and hanger elements for supporting casing and tubing are located on the ocean floor, relieving the drilling platform of structural loads. During drilling operations the underwater wellhead and well bore communicate with the drilling platform through extended casings or risers attached to the wellhead and extending above the water line. This method allows the well to be completed or temporarily abandoned on the ocean floor leaving the well relatively free of ocean going traflic and structural support problems.

However, extended casing methods create some problems. One of the problems is how to provide for remote casing or tubing suspension underwater without seriously reducing access to the well bore. Most wellheads provide a supporting surface for hangers by being tapered or by having internal shoulders therein. In either case the access available for introducing tools and equipment into the well is somewhat reduced. Special hangers and wellheads have been developed to overcome this problem, each with disadvantages as well as its advantages. On surface wells retractable lockscrew supports such as in Pierce Patent 3,248,132 of Apr. 26, 1966, have been employed. However, such a solution is not readily adaptable to underwater wells in which the wellhead is relatively inaccessible.

The present invention presents a solution to the problem by providing a retractable shoulder within the underwater wellhead. The shoulder, cut in segments, is positionable in the wellhead by hydraulic or pneumatic means to provide up to a full 360 degree shoulder for hanger support. When not being used for support, the shoulder 3,438,653 Patented Apr. 15, 1969 ice is completely retracted within a groove on the interior of the wellhead, thereby presenting full access to the well.

It is, therefore, a primary object of the invention to provide a wellhead support for casing and tubing hangers which will allow complete access to the well bore prior to introduction of the pipe string to be suspended.

Another object is to provide a remote means for positioning retractable shoulder means within a wellhead.

Still another object is to provide a retractable circumferential hanger support within a wellhead which will allow continuous fluid flow through the wellhead.

Other objects will become apparent from the following description and drawings in which:

FIGURE 1 is an elevation, partially in section, of a wellhead embodying the invention, supporting a hanger and easing therein;

FIGURE 2 is an elevation in section of the wellhead in FIGURE 1 shown with the hanger and casing removed and its support shoulder retracted;

FIGURE 3 is a plan view of the retractable shoulder of FIGURES l and 2 with flow passage modifications; and

FIGURE 4 is an elevation of the shoulder of FIGURE 3 taken along line 44 in FIGURE 3.

Referring first to FIGURE 1, a casing hanger 1 and its attached casing 2 are shown suspended in wellhead 3 on retractable shoulder 4. Casing hanger 1 is a plain mandrel type commonly known in the industry as a boll weevil hanger. However, any hanger which seats on a shoulder may be used.

To more fully understand wellhead 3, reference is also made to FIGURE 2 which shows the wellhead 3 with hanger 1 and easing 2 removed. A large groove 5 formed by a downwardly and inwardly slanting frusto-conical shoulder 5a and an upwardly and inwardly slanting frustoconical shoulder 5b is provided on the interior of wellhead 3. Retractable shoulder 4 comprises a plurality of retractable segments 4a. Each segment slidingly rests on the lower shoulder 5a of groove 5. At the base of shoulder 5a a flat circularly extending shoulder 6 whose surface is shown at right angles to the bore is provided to act as a stop for the segments of shoulder 4. Segments 4a are easily made by machining an annular ring to conform to the shape as shown in FIGURES 3 and 4. The inner and outer faces are frusto-conical surfaces. The outer face 14 corresponds to the adjacent surface of shoulder 5a when shoulder 4 is resting at shoulder 6. The inner face 15 cooperates with the hanger mandrel 1 to form the hanger support surface. The upper and lower faces 16 and 17 are upwardly and inwardly slanting frustO-conical surfaces. The annular ring is cut into a plurality of equal segments 4a to allow them to slidingly move upwardly and outwardly on shoulder 5a. At the uppermost position on shoulder 5a segments 4a are completely within groove 5 and do not penetrate the bore diameter of wellhead 3. Thus, full bore access is obtained. When lowered to the lowermost position on shoulder 5a, segments 4a form a continuous shoulder 4 around the interior of wellhead 3.

To impart movement to segments 40 each one is connected to a piston 7 by rod 8. Piston 7 moves in a hydraulic cylinder 9 within wellhead 3. The axis of cylinder 9 is parallel to inclined shoulder 5a. Cylinder 9 is connected to a remote hydraulic pressure source through port 10 and conduit 11, and to another source through conduit 7a. Piston 7 and, consequently, segments 4a are held at their uppermost positions by pressuring cylinder 9. To move segments 4a downwardly and radially inward, fluid pressure is applied above piston 7 through conduit 7a, and the pressure in cylinder 9 below the piston is relieved. Segments 4a, thus are moved into position forming shoul der 4. Alternatively, a spring return may be used to lower the segments To allow fluid flow through wellhead 3 for cementing fluid returns, etc., flow passages in the form of ducts 12 are provided in the sidewall of wellhead 3. Ducts 12 open into wellhead 3 below shoulder 4 and at the upper portion of groove 5. However, fluid flow might be obtained through space between segments 4a by making segments 4a less than 90 degrees, for example, say 45 degrees. Flow might also be maintained by providing passages 13 through segments 4a. For illustration these passages are shown in FIGURES 3 and 4. In this manner shoulder 4 would still provide 360 degree support.

Before introduction of casing 2 and casing hanger 1, segments 4a are held in a retracted position by pressurizing cylinder 9 from a remote location, such as the drilling platform. Thus, the bore of wellhead 3 is completely free of bore penetrating shoulders. Tools and equipment pass therethrough without interference. When it is desired to suspend casing 2 from wellhead 3, the pressure in cylinder 9 is relieved, allowing segments 4a to move downward and radially inward to form continuous shoulder 4. Thus, an obstruction free well bore is remotely provided with support on which a casing hanger may depend.

Although several embodiments of the invention are discussed herein, others will be obvious to one skilled in the art without departing from the spirit of the invention.

I claim:

1. Pipe suspension apparatus comprising:

tubular wellhead means, said wellhead means having a circumferential groove therein, the lower surface of said groove being a downwardly and inwardly slanting frusto-conical surface;

shoulder means encircling the bore of said wellhead means providing a substantially 360 degree upwardly facing frusto-conical support surface, said shoulder means being a plurality of segments slidingly retractable on said lower surface of said groove;

hanger means resting on said shoulder means leaving an annular space between said hanger means and said wellhead means;

duct passage means outwardly of said hanger means communicating with said annular space above and below said shoulder means to allow fluid passage from below said shoulder means to above said shoulder means; and

remotely operable means to slidingly retract said segments of said shoulder means to free said wellhead bore of all obstructions.

2. The combination of claim 1 wherein said passage means comprises:

fluid ducts longitudinally disposed in the sidewalls of said wellhead means, said fluid ducts having openings on the interior of said wellhead means above and below said retractable shoulder means.

3. The combination of claim 1 wherein said passage means comprises:

fluid ducts through said retractable shoulder means.

4. The combination of claim 1 wherein said remotely operable means to retract said shoulder means are within said wellhead means.

5. The combination of claim 1 in which said remotely operable means includes a piston and cylinder device, said piston being connected to said shoulder means by a rod, said cylinder being attached to a remotely operable fluid pressure source.

References Cited US. Cl. X.R.

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