US3512583A - Service chamber for underwater well - Google Patents

Description

May 19, 1970 T. K. JAMES SERVICE CHAMBER FOR UNDERWATER WELL .4 Sheets-Sheet 1 Filed Feb. 28, 1968 I I/II FIG.

INVENTOR.

THEODORE K. JAMES BY 5,4,, u. 444- May 19, 1970 T. K. JAMES 3,512,583

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THEODORE K. JAMES BY lid-w w. 64L;

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SERVICE CHAMBER FOR UNDERWATER WELL Filed Feb. 28, 1968 .4 Sheets-Sheet 4 INVENTOR. THEODORE K. JAMES BY RM w m Arrolnty United States Patent O 3,512,583 SERVICE CHAMBER FOR UNDERWATER WELL Theodore K. James, Norman, kla., assignor, by mesne assignments, to Transworld Drilling Company, a corporation of Delaware Filed Feb. 28, 1968, Ser. No. 708,982 Int. Cl. E21b 33/035; B63c 11/00 US. Cl. 166-.5 9 Claims ABSTRACT OF THE DISCLOSURE A chamber which provides working access to an underwater well so that workmen can perform well servicing operations on wells which are completed underwater while working in atmospheric conditions. The apparatus comprises a base plate and a working chamber which can be lowered to the base and joined thereto to form a watertight working area about a wellhead. A seal comprising an elastomeric member adapted to be forced into sealing engagement around an upper conduit section extending from the base is provided.

BACKGROUND OF THE INVENTION In exploiting oil deposits found under bodies of water, such as are found under the Gulf of Mexico, numerous techniques have been developed for completing and producing wells drilled into such deposits. Most of the techniques have involved extending the well structure to a point above the water surface so that the wells will be accessible for production and servicing operations that may be required from time to time. Such techniques have been satisfactory in many cases in the past, but as the depth of water in which offshore operations are conducted increases, the problems associated with abovewater completions increase. For example, protective structures have to be provided for the above-water portion of the wellhead, and these structures become cumbersome and expensive in deep waters, such as in depths of 150-300 or more feet. Also, these above-water completions constitute a hazard to navigation, and must be provided with suitable warning devices.

As the shallower regions of offshore areas throughout the world become developed, the natural tendency will be to explore in increasingly deeper waters, and there will be a need for improved completion and servicing techniques for these deep water operations. There has been a tendency toward underwater completions in these deeper waters, and several systems have been used with varying degrees of success. One such technique involves the use of divers to perform the work under water. The limitations and disadvantages of this technique are obvious, and need not be described. It has also been proposed to provide an underwater working chamber about a submerged wellhead so that workmen can be transported to and from the working area under atmospheric conditions, avoiding the necessity of pressurized diving equipment and men. One example of such apparatus is described in US. Pat. No. 3,202,216. This patent describes an apparatus which provides a working chamber at atmospheric conditions about an underwater wellhead, and provides a continuous elevator for transporting workmen to and from the working chamber.

Another of these techniques is described in US. Pat. No. 3,353,364, which describes a structure providing an atmospheric working chamber about an underwater wellhead, and which includes enclosed elevator capsules for transporting workmen to and from the working chamber.

SUMMARY OF THE INVENTION The present invention relates to improved apparatus for providing a watertight working area at atmospheric conditions about a submerged wellhead.

According to this invention, a base portion, which is preferably of impervious metal plate, with an opening for the well pipe to pass through, is permanently attached to the submerged drive pipe of an offshore well in a fiuid tight manner and is provided with an upper conduit section extending above the base portion and adapted to be sealably engaged by sealing means provided on a chamber section which is adapted to be lowered from the surface in a guided manner down to the base portion, attached to the base portion by sealing means to provide a watertight working chamber about a wellhead, and also adapted to be released from the base portion and returned to the surface for use on other wells. This chamber is preferably comprised of an upper closed section which is maintained at atmospheric conditions and in which workmen can ride during lowering and raising of the chamber, and a lower open section which is adapted to fit the base portion and be sealed thereto. This section might contain water as a result of the lowering, or it might be kept dry by means of compressed air or other means during lowering of the chamber. In any event, after the chamber is lowered to the base portion and sealed thereto, and any water removed from the enclosed lower section of the chamber, the workmen may enter the lower chamber and have access to the wellhead for performing servicing operations thereon. A related two-section chamber which is used to lower workmen in an enclosed upper section maintained at atmospheric conditions is described in US. Pat. No. 1,795,408. The apparatus described therein is specifically for rescue of personnel from submerged vessels, but many of the principals of operations described therein are applicable to the present invention.

According to this invention, an improved means for effecting the seal between the base portion and the upper chamber portion of apparatus for providing an atmospheric condition working chamber about a submerged wellhead is provided. This apparatus comprises an elastomeric member carried by the chamber portion and adapted to surround an upper conduit section extending above the base portion and to be sealably engaged therewith. The elastomeric member is forced into sealing engagement by a plurality of power-operated means adapted to force the member tightly against the upper conduit section. An auxiliary sealing means which might be used therewith includes an inflatable O-ring type device carried by the chamber portion and adapted to engage the upper conduit section when inflated. A compressible pad or gasket member may be provided on the chamber for engaging the base portion and providing still another sealing means for the device.

Accordingly, it is an object of this invention to provide an improved apparatus for use in servicing of underwater wells. It is another object of the invention to provide an improved sealing means between the base portion and the upper chamber portion of a structure which provides a working area at atmospheric conditions for servicing underwater wells.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view showing a chamber being pulled down to a base about an underwater wellhead.

FIG. 2 is an elevational view showing the chamber of FIG. 1 in place on a base.

FIG. 3 is an elevational view showing a section of the improved sealing means of this invention.

FIG. 4 is a plan view of a portion of the improved sealing means.

3 DESCRIPTION OF THE PREFERRED EMBODIMENT The following description of the preferred embodiment as illustrated in the drawing is for purposes of illustrating the invention, but it is understood that numerous variations and modifications could be made without departing from the scope of the invention.

In FIG. 1, a chamber is shown being lowered by means of a haul down cable 12 anchored to a base portion 14. The cable 12 is shown being wound up on a cable reel 16 attached to the chamber 10. The haul down cable 12 might for example be part of an acoustically operated buoy system which is permanently installed to the base portion 14 and released by a signal from the surface. A buoyant float lifts the cable 12 to the surface where it can be recovered and attached to the cable reel 16 by conventional means. The base portion 14 is shown attached to the upper end of a drive pipe 18 extending from below the mud line 20 to slightly above the mud line. The base portion 14 is generally fiat and has an upper conduit section 22 extending upwardly therefrom and surrounding a part of the wellhead equipment 24. A lowering cable 26 and a utility cable 28 are shown extending from the top of chamber 10, and they would generally be connected to a surface vessel (not shown) which transports the chamber 10 to the area of the well to be serviced.

As shown in FIG. 2, the chamber 10 has been pulled down to engagement with the base portion 14 by means of the haul down cable 12. The chamber 10 has an upper section 30 maintained at atmospheric conditions in which workmen can be transported. The lower section 32 of chamber 10 can be maintained dry during lowering by the use of compressed air within the section. Upon contacting base portion 14, a gasket 34 provides a preliminary seal between the lower section 32 and the water outside the structure. The gasket 34 is shown in FIG. 3, and may be of any suitable material. The chamber 10 may have a negative buoyancy at this point, in which case the weight of the chamber itself will aid in effecting a seal between the chamber and base portion by means of the gasket 34. In cases where the chamber 10 is positively buoyant, the seal at gasket 34 may be aided by the haul down cable 12 or by added ballast. Also, when the pressure inside lower section 32 is reduced, the resulting pressure differential between lower section 32 and the surrounding water will tend to increase the sealing force at gasket 34.

At some point after the chamber 10 has contacted the base portion 14, the pressure in the lower section 32 is bled off, so that both upper section 30 and lower section 32 of chamber 10 are approximately at atmospheric conditions. At this point, the workmen in upper section 30 may open the hatch 36 and enter the lower or working section 32 of chamber 10. Prior to opening the hatch 36 and entering lower section 32, the workmen can actuate the primary seal 38 to insure that the chamber 10 is maintained in place and watertight.

As shown in FIGS. 3 and 4, the primary seal 38 com prises an elastomeric member 40 which surrounds the upper end of conduit section 22. The elastomeric member 40, which may be rubber or other suitable deformable material, is attached by suitable adhesive (not shown) or by bolts 42 extending from within the member 40 through rigid segmented backing means 44 and secured thereto by nuts 46. Wedges 48, actuated by power means 50, engage mating surfaces 52 of sloped members 54 attached to segmented backing means 44. When the wedges 48 are moved downwardly, by contact with sloped member 54, the backing means 44 and the elastomeric member 40 are moved inwardly to engage the upper conduit section 22 in a sealing relationship. Upper conduit section 22 may have an upwardly and outwardly tapering member 56 attached thereto, as shown in FIG. 3, in which case elastomeric member 40 engages this tapered means 56, and as a result of the configuration of means 56, any positive buoyant force of chamber 10 will increase the sealing force of member 40 against the tapered means 56. The elastomeric member 40 also engages the surface 58 of plate 60 to form a watertight seal along this surface, and thereby prevents water from entering the lower section 32 of chamber 10. Springs 62 are attached to the outer shell 64 of chamber 10 and also to the rigid segmented backing means 44 which are connected to elastomeric member 40 by means of the bolts 42. The springs 62 are in tension, and when the wedges 48 are moved upwardly away from the surface 52 of means 54, will retract the member 40 away from sealing engagement with the upper conduit section 22.

As shown in FIG. 3, an additional sealing means includes an inflatable O-ring 68, carried within backing member 70, which is adapted to contact the outer surface of upper conduit 22 and form an additional seal thereabout. The O-ring 68 may be filled with air or other suitable fluid to effect the seal. There are actually three independent seals between the lower section 32 of chamber 10 and the surrounding water. One of these is provided by the elastomeric member 40, another by the inflatable O-ring 68, and the third by the gasket 34. By far the most important of the three, and the only one that could safely be used without the others, is the seal formed by the elastomeric member 40. The seal not only prevents water from entering the lower section 32, but also firmly holds the chamber 10 on the base portion 14, and it is designed so that the sealing force increases with increased buoyancy of the chamber 10. In addition, conventional O-ring seals (not shown) might be used. It will be obvious that other means, such as conventional direct acting hydraulic rams, could be substituted for the downwardly acting wedge members 48 in effecting the seal, but the downwardly acting wedge design takes a minimum of space and allows the upper conduit section 22 to be nearer the diameter of the outer shell of the chamber 10. Additional variations of details within the scope of the invention will be obvious to those skilled in the art.

What I claim is:

1. Apparatus for use in servicing an underwater well comprising:

(a) a lower base portion attached to a conduit surrounding the upper portion of said well;

(b) an upper conduit section extending upwardly from said base portion;

(0) an independently transportable chamber, having a lower open section, capable of being transported to a region above the well, lowered from the surface and thereafter sealably attached to said upper conduit section to provide a watertight working area about a wellhead;

(d) means for sealably attaching said chamber to said upper conduit section only after the chamber has been lowered onto said upper conduit section comprising:

(1) an elastomeric member adapted to surround said upper conduit section; and

(2) means for urging said elastomeric member into sealing engagement between said upper conduit section and said chamber to thereby provide a watertight seal.

2. Apparatus as defined in claim 1 in which the portion of said upper conduit which is contacted by said elastomeric member is tapered upwardly and outwardly to thereby increase the sealing force when a positive buoyant force acts on said chamber.

3. Apparatus as defined in claim 1 in which an inflatable member is provided which surrounds said upper conduit section and when inflated contacts same to provide an additional seal between the upper conduit section and the chamber.

4. Apparatus as defined in claim 1 in which a gasket capable of forming a watertight seal between the chamber and the lower base portion is provided on the lower surface of the outer shell of the chamber 5. Apparatus as defined in claim 1 in which the means for urging the elastomeric member into sealing engagement with the upper conduit section comprises a plurality of poweroperated wedge members adapted to force the elastomeric member inwardly.

6. Apparatus as defined in claim 5 including a plurality of spring means adapted to pull the elastomeric member away from the upper conduit section when the wedge members are not forcing the elastomeric member against the upper conduit section.

7. Apparatus for use in servicing an underwater well comprising:

(a) a first conduit surrounding the upper portion of a well and extending from below the mud line to above the mud line but below the water surface;

(b) a base portion attached to said first conduit near its upper end;

(c) an upper conduit section extending upwardly from said base portion and aligned coaxially with said first conduit, said upper conduit section being of a size to permit passage of wellhead apparatus therethrough;

(d) a chamber capable of being lowered from the surface to said base portion with at least a portion of said chamber maintained at atmospheric pressure during descent, said chamber being sealably attachable to and releasable from said upper conduit section; I

(e) means for sealably attaching the chamber to the upper conduit section comprising:

(1) an elastomeric member adapted to surround said upper conduit section and having attached to its periphery a plurality of segmented rigid backing members;

(2) a plurality of power-actuated members adapted to contact said backing members and force them inwardly, thereby effecting sealing contact of said elastomeric member and said upper conduit section; and

(3) an inflatable O-ring member adapted to form when inflated a seal betwen the chamber and the upper conduit section.

8. Apparatus as defined in claim 7 including a plurality of springs adapted to pull the elastomeric member away from the upper conduit section when the power-actuated members are not being utilized to force the elastomeric member against the upper conduit section.

9. Apparatus as defined in claim 7 in which the plurality of power-actuated members comprise wedge members oriented downwardly so that upon downward movement of the wedge members the elastomeric member is forced into sealing engagement with the upper conduit section.

References Cited UNITED STATES PATENTS 2,783,970 3/ 1957 Gillespie 166-.5 X 2,854,215 9/1958 Cox 166.5 X 2,995,196 8/1961 Gibson et al t -7 3,020,956 2/1962 Suderow 166-.6 3,202,216 8/1965 Watts et a1. 166.6 3,353,364 11/1967 Blanding et a1. 166.5 X 3,372,745 3/1968 Holmes 166.6 3,421,579 1/1969 Manning 166.5

DAVID H. BROWN, Primary Examiner R. E. FAVREAU, Assistant Examiner US. Cl. X.R. 61-69

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