US3543846A - Underwater oil or gas facility - Google Patents

Description

United States Patent [72] Inventors Melvin Wilmer Smith Edgewater, Maryland; Andre George Brun, Paris, France [21] Appl. No. 776,319 [22] Filed Nov. 18, 1968 [45] Patented Dec. 1, 1970 [73] Assignee Westinghouse Electric Corporation Pittsburgh, Pennsylvania a corporation of Pennsylvania [54] UNDERWATER OIL 0R GAS FACILITY 12 Claims, 7 Drawing Figs.

[52] [1.8. CI 166/.5, 166/267 [51] Int. Cl. E2lb 33/035, E21b 43/00 [50] Field ofSearch 166/.5, .6, 267; 175/89; 61/46, 46.5

[56] References Cited UNITED STATES PATENTS 2,171,672 9/1939 Plummer 175/9X Primary Examiner-Marvin A. Champion 7 Assistant ExaminerRichard E. Favreau Attorney-Brady, OBoyle and Gates ABSTRACT: An integrated underwater structure of a generally frustoconical configuration located on the bottom of the sea which serves a plurality of functions with respect to an offshore oil or gas well. When installed on the sea floor, the structure can be utilized not only as a platform for drilling but also as an oil and/or gas production facility, an oil-gas separation facility, and even as an underwater storage facility, or any combination thereof. Furthermore, the structure is adapted to provide a base for or completely enclose the wellhead and includes means whereby a submerged vehicle can automatically position and attach itself to the structure in proximity to its apex.

Ptented 1, 1970 Sheet L or 2 FIG] INVENTORS MELVlN -w. SMITH BY ANDRE aaauu ATTORNEYS Patented Dec. 1, 1970 Sheet 2 or 2 UNDERWATER OIL OR GAS FACILITY CROSS-REFERENCE TO RELATED APPLICATION The present application is related to an application entitled Locating and Attachment Means for a Submersible Vehicle, Ser. No. 776,478, filed on Nov. 18, 1968, in the name of the present inventors and assigned to the assignees of the present invention.

BACKGROUND OF THE INVENTION The present invention relates to offshore oil and gas facilities and more particularly to means for drilling and maintaining such a well without the necessity of elaborate structures such as Texas Towers which extend from the sea bottom through to the surface of the water. Not only are such structures costly but are extremely vulnerable to the elements of nature and to shipping. Furthermore, there shallower a certain depth limitation to which such structures can be constructed. In shallower water, however, wells can be completed simply by means of cylindrical jackets which extend from the bottom of the sea to the surface of the water. But in deeper water where depths of up to 340 .feet are concerned, the Texas Tower type of structure is utilized. There still exists, however, the limitation on the depth to which structures can be built.

There have been attempts to drill and maintain wells which are completely submerged. However, such structures are susceptible to dragging anchor chains or nets and, therefore, become a hazard to commerce. What is desirable, therefore, is better means for establishing and maintaining oil and gas wells on the floor of the sea at not only the shallower depths presently being exploited for such purposes but also for reaching depths and establishing wells thereat heretofore inaccessible.

SUMMARY The present invention is directed to an improved underwater oil-gas facility comprising a reinforced concrete structure having a generally frustoconical configuration with a circular opening extending therethrough along the central axis thereof. The frustoconical structure is located on the floor of the sea with its larger dimension in contact with the floor and its conical surface being directed towards the sea surface. A cylindrical shaft is inserted through and attached to the structure such that one end is interior of the central opening while the other end extends into the sea floor providing not only an anchorage for the structure but a guide and support for the well casings, etc., extending into the well. At least one circular recess or groove having its center substantially alined with the central axis of the structure is provided on the outer surface'of the structure substantially parallel to the sea floor which is adapted to act as a docking ring for an underwater vehicle. The frustoconical structure may comprise a single unit or may be comprised of a first or larger base section in combination with one or more smaller nesting sections which are adapted to contain a production facility coupled to the well through the opening provided in the base section. When used for storage of oil or chemicals, a flexible conduit is coupled to the structure and embodies a springlike spiral wound about the surface of the structure and which is adapted to extend to the sea surface thereby providing a flexible yet self-recoiling member that assumes or at least seeks a rest position around the frustoconical structure.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of one embodiment of thesubject invention located beneath the surface of the sea and being coupled to a vessel on the surface by means of a flexible conduit in the form of a spiraled coil;

FIG. 2 is a central cross-sectional view of one embodiment of the subject invention and disclosing a frustoconical structure including a base section and one type of nesting upper section adapted to be lowered into registration therewith;

FIG. 3 is a perspective view of another embodiment of the subject invention having a concave outer surface;

FIG. 4 is a perspective view of one embodiment of the present invention additionally including one type of well production apparatus affixed to the top of a frustoconical base section;

FIG. 5 is a fragmentary perspective view partially in section of another embodiment of the subject invention additionally including a well maintenance chamber scaled large enough to permit access thereto by a human operator;

FIG. 6 is an enlarged cutaway section of a nesting unit or section located at the apex or top of the base contemplated with the embodiment shown in FIG. 5 including the well maintenance chamber;

FIG. 7 is a fragmentary'perspective view partially in section of yet another embodiment of the subject invention similar to that illustrated in'FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and particularly to FIG. 1 there is illustrated a frustoconical structure 10 having its larger circular dimension 12 located on the floor 14 of the sea. The structure 10 comprises a base section and is preferably constructed of concrete and steel thus providing a structure which is characteristically unique in its strength of resistance to external pressure or forces in addition to having long life and resistance in the environment of sea water. Furthermore, the frustoconical base section 10 is adapted to serve a plurality of purposes such as a template for well drilling, an underwater platform, a production facility, a separation facility, a storage facility for liquids greater and lesser than the specific gravity of water, or any of these combinations in connection with a well drilled into the sea floor 14 for obtaining petroleum products such as gas and/or oil. Furthermore after a well, a not shown, has been drilled into the floor 14 of the sea through the central axis of the frustoconical structure 10, oil or gas production equipment, not shown, can be housed either totally within the base section 10 or in a mating or nesting structural unit or section'l6 at the top 18 thereof. Moreover, in the embodiment of the structural unit or upper section 16 shown in FIG. 1 it is adapted to have an outer surface conforming to the frustoconical configuration of the structure I0. Such a shape will prevent foreign elements such as dragging anchors and nets used in trawling from becoming entangled therewith due to the fact that anchors will ride over it or be deflected around it while nets used in trawling will ride over it.

Additionally, a pair of circular recesses or grooves. 20 and 22 are concentrically located a predetermined fixed distance apart on the surface of either the section 10 or the section 16. It should also be understood that when desirable, however, one circular groove 20 may be located on the upper section 16 while the lower groove 22 may be located on the lower or base section 10. The purpose of the grooves 20 and 22 is to provide a means by which a predetermined location such as the top 24 of the upper section 16 may be precisely found by an underwater vehicle or device, not shown, by moving up the outside surface and diminishing diameter of the lower section 10 from the bottom 12 to the first or lower groove 22. The recesses 20 and 22 moreover provide a means whereby said vehicle may attach itself thereto for performing work at the lo cation of the upper section 16. The grooves 20 and 22 then act as a pair of docking or mooring rings" for a vehicle approaching and attaching itself to the integrated frustoconical configuration shown in FIG. 1.

A hollow, flexible conduit 26 is also shown in FIG. 1 being wound in a spiral around the base section 10. It is adapted to extend to the surface of the sea 28 and be coupled to a surface vessel 30, such as an oil barge or tanker. The spiral configuration of the flexible conduit 26 allows free movement of the surface vessel 30 about the integrated sections 10 and 16 so that gas or oil may be transferred either directly from the well not shown or from storage means contained therein to the surface 28. What is significant, however, is that the conduit 26 when disengaged from the surface vessel 30 will tend to recoil about the conical base section 10. For example, the conduit 26 may completely submerge and completely wrap itself around the base section or when desirable the upper terminus of the conduit 26 may be attached to a buoy, not shown. In the latter case, however, the buoy will have a tendency to aline itself over the top 24 of the underwater structure.

Considering the invention now in further detail, reference is made to FIG. 2 wherein a central cross section of a frustoconical base or lower section 10 is shown having a relatively thick flat circular base portion 13 including a circular central opening 15 located on the floor 14 of the sea. An inclined outerwall portion 17 extends upwardly from the outer edge of the base portion 13 defining an interior angle therebetween of approximately 60 (as shown). A' closed circular inner wall portion 18 extends axially from the central opening 15 to an intersection with the outer wall portion 17 to provide a relatively largediarneter opening or bore 21 through the lower section 10 from its lower surface 19 to its apex 23. Furthermore, the opening 21 is enlarged at the apex 23 and includes an inwardly sloping shoulder surface 30.

A relatively large-diameter pipe 32 is inserted through the central opening 15 of the base portion 13 and is either driven,

jetted, or drilled into the sea bottom 14. It is then bonded to the inside diameter of the base portion 13 at the central opening 15 by means of a suitable cement 36. The pipe 32 moreover extends into the opening 21 such that subsequent well drilling and placing of smaller casings such as the well casing 38 make it a concrete and steel reinforced pile of great strength in addition to providing a well which has a protected opening. It also provides an adequate base for a wellhead to be housed totally within or at the top of the base section 10.

In the embodiment shown in FIG. 2 oil-gas production apparatus shown generally in diagrammatic form by the assembly 40 comprises a first type of upper section 16 and is shown located above the conical section 10 so that it is adapted to be lowered into the opening 21. This process may either be carried out by means of guide lines, not shown, or by means of sonar devices which operate in a well-known manner to position and seat the lower surface 42 of the assembly 40 against the shoulder surface 30 of the lower section 10. The outer surface 44 of the assembly 40 has a contour conforming to the frustoconical surface of the lower base section 10 and is an extension of the inclined outer wall portion 17 when lowered into the opening 21.

The contents of the assembly 40 are shown schematically comprising inter alia a protrusion tube 46 which is adapted to fit into the well casing 38, a coupling or connecter 48 which attaches to the end of the well casing 38, and a master valve assembly 50 coupled into a Christmas tree assembly 54. Outputs 56 and 58 from the Christmas tree 54 are adapted to couple into the conduits 60 and 62, respectively, when the assembly 40 is nested into the lower base section 10. The outputs 56 and'58 moreover may provide outputs of oil and/or gas which is then fed to a separator such as toroidal separator 64. A valve assembly 65 then connects the separator 64 to a conduit such as the flexible conduit 26 shown in FIG. 1, or to a structure not shown.

However, it should be observed that when desirable the output of the well may be fed directly to the surface of the sea through an apparatus similar to the integrated assembly 40 but wherein a conduit not shown, is coupled directly to the surface 28 of the seafrom the Christmas tree and valve assemblies 54 and 50, respectively.

It was noted above that the lower section 10 is constructed in such a manner that the interior angle described by the base portion 12 and the sloping outer surface 17 is preferably in the order of 60. Furthermore, the section 10 is not a solid structure but contains a hollow cavity 67 therein so that when desirable the structure can be made buoyant and towed to the site and then sunk prior to having the pipe 32 inserted and cemented thereto for anchoring structure on the sea floor 14. Additionally, the base portion 12 may be of a greater thickness than the outer side wall 17 and the inner wall 18. This helps to provide the desired vertical stability of the structure. Furthermore, the cavity 67 may then be used for storage of chemicals for injection into well fluid.

It should also be observed that when the frustoconical section 10 is in place on the sea floor 14 as shown in FIG. 2 a BOP stack with an extension piece can be lowered into the opening 21 in the same manner as the assembly 40 shown in FIG. 2 for the actual drilling of the well as was briefly referred to at the beginning of the specification.

.While the general conical configuration is the preferred form of the invention it should be observed that when desirable, the sections 10 and 16 of FIGS. 1 and 2 may take the form of a truncated hyperboloid of one sheet such as shown in FIG. 3. Referring now briefly to FIG. 3 there is shown a hyperboloid lower base section 10' with a pair of grooves 20 and 22 located near the top thereof and an upper section 16' having an outer surface corresponding to the outer surface of the structure 10. This configuration is also able to provide omnidirectional access by a submersible, not shown, coming in contact and riding up the outer hyperbolic surface of the structure 10 and is also adapted to prevent dragging anchors and nets from becoming entangled therewith.

The inventive concept is not intended to be limited to the configurations shown with respect to FIGS. 1, 2 and 3 but is intended to cover at least two additional embodiments. The embodiment shown with respect to FIG. 2 pertains to a frustoconical configuration wherein a well production assembly 40 is lowered into a nesting position with a frustoconical concrete and steel lower section 10. Referring now to FIG. 4, there is disclosed another embodiment of the invention' which in addition to the frustoconical base section 10 similar to that disclosed with respect to FIG 2 including the concentric vehicle docking grooves 20 and 22 additionally discloses a well production assembly 66 which is adapted to be mounted onlhe top of the conical structure 10. The assembly 66, however, extends upwardly therefrom in a substantially cylindrical housing whereas the apparatus shown in FIG. 2 is adapted to nest down into the interior of the conical section 10. The assembly 66 is adapted to include the necessary control and telemetry devices, valves and chokes comprising the Christ mas tree, and suitable power sources necessary to operate the apparatus independently at the site. The configuration shown in FIG. 4 moreover pertains to an embodiment in which the entire package 66 is periodically moved and replaced. This is accomplished by means of a valve opening and closing mechanism generally shown by reference numeral 68 which is adapted to provide simple coupling and decoupling from the well by means of a rotating ring 70. Moreover, this coupling is adapted to be performed by a simple rotation of the ring 70 which may be performed by a manipulator, not shown, attached to an underwater vehicle which seeks out and attaches itself to the structure 10 by means of the grooves 20 and 22 just as in the case of the embodiment shown with respect to FIG. 2.

And still another embodiment of the subject invention is shown in FIGS. 5 and 6 which discloses an oil or gas facility which is adapted to be capable of housing a human operator who may from time to time be required to perform periodic maintenance or some such activity at the wellhead. Directing attention now more particularly to FIG. 5 there is disclosed a relatively larger frustoconical lower base section 72 such as shown in FIG. 2 upon which a production facility is enclosed in a second or upper section 74 whose external surface generally corresponds to the outer surface of the frustoconical section 72. The section 74 contains an interior work chamber 76 which is adapted to house such apparatus as the assorted valves and chokes generally referred to as a Christmas tree" 78. Additionally, the work chamber 76 is axially alined with the center of the conical sections 72 and 74 and is of sufficient size to permit movement in and about the Christmas tree" 78 by a human operator. Access to the workchamber 76 is by means of a flanged opening 80 at the top of the upper section 74. In the interior of the structure external to work chamber 76 is a hollow space 79 which is adapted to contain such apparatus as a toroidal gas-oil separator 82 and the necessary life support apparatus and associated instrumented energy source packages generally referred to by reference numeral 84. Additionally, as opposed to the pair of concentric grooves 20 and i 22 located on the conical structure as illustrated by FIGS. 1 through 4 of the present embodiment of the present invention includes a pair of concentric recessed docking grooves 86 and 88 located along the outer surface of the upper section 74.

The upper section 74 of the embodiment shown in FIG. 5 including the work chamber 76 is shown in greater detail in FIG. 6 wherein the work chamber 76 comprises a generally cylindrical chamber having rounded comers for purposes of withstanding the pressures involved at great depths beneath the sea. A well casing illustrated by reference numeral 90 is fed up through a cylindrical jacket 92 axially alined with the inner wall portion 94 of the base section 72. The interior of the jacket 92 may include several work or storage levels and provides access to the ocean floor, not shown. The well casing 90 is coupled to the Christmas tree 78 which is shown coupled to a separator 82. The toroidal separator 82 may be located exteriorly of the work chamber 76, being coupled to the Christmas tree" 78 by suitable plumbing apparatus 93.

A human operator may have access to the work chamber 76 and the associated facility by means of the opening 80 in the upper section 74, being transported thereto by means of a vehicle-carried life support capsule 95. For example, a vehicle may attach itself to the structure 74 by means of the grooves 86 and 88 and locate a manned capsule 95 at the flanged opening 80. The human operator then leaves the capsule 95 and enters the chamber 76 by means of the hatches 96 and 98, it being understood that suitable sea removal and pressure apparatus is included to permit safe transfer from the capsule 95 into the chamber 76. r

A further modification of the embodiment shown in FIGS 5 and 6 is illustrated in FIG. 7 wherein a toroidal separator 100 having a relatively larger capacity as opposed to the separator 82 shown in FIGS. 5 and 6 is located in the hollow interior 101 of the frustoconical section 72. The well production structure or upper section 74 is located on top of the structure 72 in a manner previously disclosed and additionally contains the work chamber 76 and the access opening 80 at the top thereof. An additional difference is the location of one docking groove 86 on the structure 74 while the other docking groove 88 is located on the structure 72. The grooves 86 and 88 still are concentric and are located a fixed distance apart and are adapted to provide an attachment means for a docking submersible approaching at any angle to the configuration shown.

What has been shown and described therefore is a cone configuration which when installed on the sea floor can be a template for drilling, an underwater platform, an oil-gas production facility, an oil-gas separation facility, a storage facility for liquids greater or lesser than the specific gravity of water or any or all of the combinations as well as providing strength, protection means for attachment to the sea floor, means for submersible attachment and means for loading or unloading stored liquids while being a relatively simple construction.

While there has been shown and described what is at present consideredto be the preferred embodiments of the invention, modification thereto will readily occur to those skilled in the art. It is not desired, therefore, that the invention be limited to the specific arrangements shown and described but it is to be understood that all equivalents, alterations, and modifications coming within the spirit and scope of the invention are herein meant to be included.

We claim:

1. An underwater facility anchored in the sea floor for offshore oil or gas apparatus comprising in combination:

a submerged structure utilized in connection with said apparatus and having a base portion adapted to rest on the t sea floor and including a central opening therethrough for access to said apparatus, inclined outer wall portion means extending upwardly from the outer edge of said base portion and defining an interior acute angle with said base portion, and closed inner wall portion means extending from said central opening to an intersection with said inclined outer wall portion means thereby providing a hollow interior chamber therebetwecn and an axial opening extending entirely through said structure;

an elongated member having a central opening extending entirely through itslength for providing anchorage means for said submerged structure, said elongated member extending through said axial opening adjacent said base portion a predetermined distance into said structure and a predetermined distance into the sea floor; and

bonding means applied between the adjoining outer surface of said elongated member and the outer surface of said inner wall portion for attaching said elongated member to said submerged structure thereby stabilizing and holding said structure to the sea floor.

2. The invention as defined by claim 1 wherein said submerged structure comprises a substantially frustoconical base structure section and said elongated member comprises a substantially cylindrical member having a predetermined length.

3. The invention as defined by claim 2 wherein said frustoconical base section additionally includes at least one circular groove located on and around the outer surface of said inclined outer wall portion substantially perpendicular to the axis of said circular base portion and being located intermediate the ends of said inclined outer wall portion.

4. The invention as defined by claim 2 wherein said frustoconical integrated structure additionally includes a concavity having a substantially flat surface located at the intersection of said inclined outer wall portion and said closed inner wall portion.

5. The invention as defined by claim 2 wherein said integrated structure includes a pair of circular recesses parallelly disposed a fixed distance apart on and around the outer surface of said inclined outer wall portion substantially parallel to said base portion and being located intermediate the ends of said outer wall portion.

6. The invention as defined by claim 2 and additionally including an upper structure section adapted to include a well production assembly therein located and attached to the top of said frustoconical base structure section, said lower or upper sections forming an integrated frustoconical structure thereby and also' including a pair of concentric circular grooves located on and around the outer surface of said integrated structure substantially perpendicular to the axis of said integrated structure intermediate the sea floor and the apex of said upper structure section.

7. The invention as defined by claim 6 wherein said frustoconical structure additionally includes storage means located in said hollow interior and adapted to be coupled to a well production assembly.

8. The invention as defined by claim 6 wherein said upper structure section includes an oil or gas production assembly and a work chamber enclosing said productionassembly interior thereof, said work chamber being disposed substantially central axially with respect to said lower and upper structure sections.

9. The invention as defined by claim 8 wherein said work chamber additionally includes hatch means, said hatch means being of sufficient size to permit human-access to the interior of said work chamber and said production assembly located therein.

10. The invention as defined by claim 1 and additionally including a removable oil or gas well production unit attached to the top of said submerged structure, said well production unit including means for being coupled into said well when in posi-' tion, and means for shutting down said well upon being removed from said submerged structure.

face of the sea, said conduit being wound in a spiral about said inclined outer wall and being adapted to extend upwardly therefrom and having a tension spring characteristic to recoil itself around said inclined outer wall when extended and subsequently released.

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