GB1564676A - Marine structure with riser conductor and pipeline connection - Google Patents

Description

(54) MARINE STRUCTURE WITH RISER CONDUCTOR AND PIPELINE CONNECTION (7l1) We, TEXACO DEVELOP MENT CORPORATION, a corporation organised and existing under the laws of the State of Delaware, United States of America, of 135 East 42nd Street, New York, New York 10017, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - In the offshore segment of the petroleum industry one of the prevalent problems has been the connecting of an offshore platform or marine structure to a pipeline which normally carries petroleum products to an onshore storage area or from a well. Usually one or more well heads at the ocean floor are connected to a common line which conducts the products to a riser or conduit supported by the platform. The riser directs the crude liquid or gas product upwardly to a separation system at the platform's deck prior to the product being conducted away by another such pipeline, or shipped away by tanker.

As a matter of practice, the connection between the pipeline and the fluid conductor at the marine platform, is made by welding the pipe joint to the fluid conductor through the use of divers and/or highly technical equipment which is lowered to the sea floor.

In the instance of relatively deep waters, the normal problem of making the above noted connection is substantially compounded. This results primarily from the hyperbaric atmosphere which limits the use of personnel and greatly increases the cost of such an operation.

Toward simplifying this laying of the desired pipeline the present invention provides a means whereby the lower end of the fluid carrying conductor or riser is adjustably connected to the platform. In the resting position the conductor is disposed in a substantially upright disposition so that its lower open end is adjacent to the ocean floor.

A provisional conductor which subsequently forms a portion of the pipeline, is detachably connected to the marine structure in a manner to permit pivotal movement of said provisional member in a substantially vertical plane.

Pivotal movement will thus position the lower end of said provisional conductor in approximate alignment with the upright fluid conductor. Downward movement of the latter will then engage the respective members into a fluid tight connection between the pipeline and the conductor.

It is therefore an object of the invention to provide means for connecting a marine structure supported fluid conductor to a pipeline, without the necessity of operating underwater or utilizing divers.

Figure 1 is a perspective view of a marine structure according to the invention; Figures 2 and 3 are fragmentary views of a conduit connecting segment respectively in a provisional position and an aligned position for connection; Figure 4 is a view of the structure illustrating a step in a method according to the invention; and Figure 5 is a fragmentary view of a pivot means for a conduit.

Referring to the drawings, an offshore or marine platform 10 of the type contemplated is shown as comprising a plurality of upstanding columns or legs 11 and 12 which include lateral support members or braces 13 and 14 extending therebetween. A working deck 16 is supported at the legs' upper ends. When positioned at an offshore working site platform 10 is arranged substantially vertically such that the respective support columns assume an upright disposition. After the structure is positioned in place from a carrying barge or the like, piles 17 are driven through the respective legs into the substrate, whereby to fixedly anchor the entire unit and permit operation thereof at the working site.

Toward facilitating the producing process, the crude product is normally led from a series of well heads dispersed at the ocean floor. It is then conducted through a pipeline and/ manifold system, and thence upward through a riser or fluid conductor member 18 which depends from platform 10. Deck 16 normally carries equipment to initially treat or process the crude product. One such initial treatment is to separate gas and/or water from liquid product prior to the latter being further pipelined to shore, or loaded onto a cargo vessel or tanker.

Elongated tubular fluid conductor 18 is disposed preferably adjacent one side of the marine structure. Said conductor 18 comprises in one form, a series of end connected pipe sections of sufficient diameter to carry the flow of fluid which will be pumped or forced from the subsea pipeline. This fluid conductor, also referred to herein as a riser, terminates at the platform deck such that it can be readily connected to appropriate treat ing apparatus such as a gas separator or the like. The lower end of said fluid conductor 18 is provided with a flange or a suitable coupling member 15 for achieving a fluid tight connection with pipeline 19 as will be hereinafter noted.

Conductor 18 is adjustably positioned with respect to the various lateral brace members 13 and 14. Preferably it is located between adjacently positioned support columns 11 and 12, by a series of vertically arranged clamping members 21, 22 and 23. Said clamping mem bers are adapted to not only position conductor 18 horizontally, but also to position it verti cally such that the entire conductor can be adjusted upwardly or downwardly for the purpose of achieving the fluid tight connection with pipeline 19 as will be hereinafter noted.

A provisional flow conductor 24 is similarly connected to one side of marine structure 10, being positioned adjacent to the above described fluid conductor 18. Said provisional conductor 24 comprises in essence an elon gated upper and defined by a plurality of end connected pipe lengths which will subsequently form a portion of the floor supported pipeline 19. Said provisional conductor 24 is provided at the lower end with a connecting segment 26.

Connecting segment 26 includes in essence a section of pipe or conductor having a diameter comparable to the diameter of fluid conductor 18, and being so formed to define a desired angle between the various respective legs 27 and 28. Said angle is such that a proper connection can be made with fluid conductor 18, after provisional conductor is lowered to the ocean floor.

Thus, when provisional conductor 24 is initially fabricated as an integral part of marine structure 10, it is held in place by a plurality of spaced apart clamps or similar restraining members 29, 30 and 31. Each of said clamps is remotely operable to an open position whereby the entire provisional con ductor 24 will be released from its clamped connection to the platform 10.

The lower end of said provisional con ductor 24 terminates at the ocean floor, and adjacent to the lower end of the fluid conductor 18. The pivotal function of said provisional conductor is achieved through use of a pivotal connection made between the connecting segment 26, and the lateral brace 32. Brace 32 is provided with spaced apart pivot blocks 33 and 34 (Fig. 5) in a manner to slidably receive hinge pins or shafts 36 which depend from, and are fixedly positioned to the connecting segment 26. Said hinge pins 36 are so positioned by an extension arm 37 to maintain a position in substantial vertical alignment with the fluid conductor 18. Thus, when the provisional conductor 24 is lowered to its operating position at the ocean floor, the leg 27 of said conductor segment 26 will pivot into an upstanding position in alignment with the lower end of fluid conductor 18.

To facilitate proper positioning of the connecting segment 26 when the provisional conduaor 24 is in the lowered position, one or more guide members are provided. For example, saddle guide 38 is disposed on lower lateral brace 39 in such a position to constitute an abutment with leg 28 of connecting -segment 26 when the latter is adjusted to a substantially vertical position. A similar transverse guide means can be provided to receive and properly align leg 27 of said connecting segment 26 with the lower end of the fluid conductor 18.

As above mentioned, with respect to the fluid conductor 18, connecting segment 26 remote end can be provided with a suitable flange or cooling member 41 adapted to engage the corresponding member 15 of said fluid conductor 18. This engagement in accordance with the precepts of the invention, can be remotely instituted through a hydraulic or pneumatic system which is actuated at platform deck 16. Thus, the physical joining of pipeline 19 with the conductor 18 can be made without the need for diver participation, and with a minimal possibility of technical difficulty.

Operationally, the entire marine structure 10 is normally assembled in a shore based fabrication yard. Said assembly includes the positioning of not only the fluid conductor 18 a predetermined distance from the lower end of the marine structure 10, but also the positioning of the provisional conductor 24 so as to be operable as herein noted.

Upon completion, the marine structure 10 is normally floated or barged to a desired offshore working site, and after being lowered into the water is fixedly positioned therein by piling or similar means. With the platform firmly fixed, the upper end of the provisional conductor 24 as well as fluid conductor 18, will protrude beyond the structure's working deck.

To commence the connecting operation a lay barge or similar vessel 46 (Fig. 4) is utilized to add additional sections of pipe to the upper end of the provisional conductor 24.

Said barge 46 is further equipped to engage the upper end of said provisional conductor 24 and progressively draw it away from marine structure 10 after the retaining clamps 29 and 31 have been released. In the normal manner laying a length of pipe, the provisional conductor 24, which now assumes the function of a segment of pipeline 19 will be supported if needed by a stinger 47 or similar member depending from the lay barge. As the barge progresses away from structure 10, tension is applied to the provisional member and simultaneously additional lengths of pipe are added thereto.

With the addition of such pipe lengths, provisional conductor 24 will assume the desired, general "S" configuration between the surface of the water and the floor of the ocean. In its ultimate position the lower end of the provisional structure 24, i.e. the elongated pipe section, will come to rest such that connecting segment 26 is generally uprightly disposed and in alignment with the lower end of the fluid conductor 18.

In such a position, connection between said two members is achieved by releasing the holding damps 21, 22 and 23 which retain and position fluid conductor 18. The latter, then being supported by a derrick or similar means at the upper end, is lowered into physical contact with the connecting segment coupling member. If a proper mating action is achieved, the coupling of said members can be made remotely by actuation of the auto matic coupling system at deck 16.

With pipeline 19 now connected to the fluid conductor 24, the remaining lengths of pipe can be progressively added to the provisional conductor such that the latter lays in its entirety on the ocean floor, thereby forming an integral part of the pipeline.

WHAT WE CLAIM IS: 1. A marine structure comprising at least one support column and a deck carried by said support column, a fluid flow conduit extending from said deck to the lower end of said support column, means mounting said conduit to said marine structure for limited movement, a second fluid flow conduit comprising a connecting segment and an elongate segment, and means mounting said second conduit to the lower end of said marine structure for pivotal movement between a provisional position in which said elongate segment extends upwardly towards said deck and a fluid flow position in which said elongate segment extends along the bed of a body of water and said connecting segment is aligned with said lower end of said first conduit to permit coupling of said first and second conduits.

2. A marine structure as claimed in claim 1 wherein said mounting means for mounting said first conduit comprises releasable clamping members whereby release thereof permits limited longitudinal movement of said first conduit into engagement with the aligned connecting segment of said second conduit in said fluid flow position.

3. A marine structure as claimed in claim 1 or claim 2 including releasable clamps operable releasably to clamp said elongate segment of said second conduit in said provisional position to said marine structure prior to pivotal movement into said fluid flow position.

4. A marine structure as claimed in any one of claims 1 to 3 including coupling means associated with the lower end of said first conduit and with said connecting segment of said second conduit, said coupling means being operable from a remote position to couple said conduits together when aligned.

5. A marine structure as claimed in any one of claims 1 to 4 including guide means secured to said marine structure and arranged to receive and locate said second conduit as it is pivoted into said fluid flow position with said connecting segment in alignment with said first conduit.

6. A marine structure as claimed in any one of claims 1 to 5 wherein said structure comprises a plurality of said support columns having a plurality of lateral braces extending therebetween, said first conduit being mounted to said lateral braces.

7. A marine structure as claimed in claim 6 wherein said pivot means comprises a pivot pin secured to said connecting segment and a pivot block secured to one of said braces.

8. A method of providing a marine structure with a fluid flow conduit extending from a deck thereof to the lower end thereof and in fluid flow connection with a fluid flow conduit extending along the bed of a body of water, comprising providing said marine structure with said first fluid flow conduit mounted thereto for limited movement, providing said marine structure with a pivotally mounted second fluid flow conduit comprising a connecting segment and an elongate segment, pivotally moving said second conduit away from a provisional position in which said elongate segment extends upwardly towards said deck into a fluid flow position in which said elongate segment extends along the bed of a body of water and said connecting segment is aligned with said lower end of said first conduit, and coupling said first and second conduits together.

9. A method as claimed in claim 8 including securing lengths of conduit to said elongate segment as said second conduit is pivotally moved down to the bed of the body of water.

10. A method as claimed in claim 9 including progressively supporting and lowering said second conduit and said lengths into a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (12)

**WARNING** start of CLMS field may overlap end of DESC **. the upper end of the provisional conductor 24. Said barge 46 is further equipped to engage the upper end of said provisional conductor 24 and progressively draw it away from marine structure 10 after the retaining clamps 29 and 31 have been released. In the normal manner laying a length of pipe, the provisional conductor 24, which now assumes the function of a segment of pipeline 19 will be supported if needed by a stinger 47 or similar member depending from the lay barge. As the barge progresses away from structure 10, tension is applied to the provisional member and simultaneously additional lengths of pipe are added thereto. With the addition of such pipe lengths, provisional conductor 24 will assume the desired, general "S" configuration between the surface of the water and the floor of the ocean. In its ultimate position the lower end of the provisional structure 24, i.e. the elongated pipe section, will come to rest such that connecting segment 26 is generally uprightly disposed and in alignment with the lower end of the fluid conductor 18. In such a position, connection between said two members is achieved by releasing the holding damps 21, 22 and 23 which retain and position fluid conductor 18. The latter, then being supported by a derrick or similar means at the upper end, is lowered into physical contact with the connecting segment coupling member. If a proper mating action is achieved, the coupling of said members can be made remotely by actuation of the auto matic coupling system at deck 16. With pipeline 19 now connected to the fluid conductor 24, the remaining lengths of pipe can be progressively added to the provisional conductor such that the latter lays in its entirety on the ocean floor, thereby forming an integral part of the pipeline. WHAT WE CLAIM IS:

1. A marine structure comprising at least one support column and a deck carried by said support column, a fluid flow conduit extending from said deck to the lower end of said support column, means mounting said conduit to said marine structure for limited movement, a second fluid flow conduit comprising a connecting segment and an elongate segment, and means mounting said second conduit to the lower end of said marine structure for pivotal movement between a provisional position in which said elongate segment extends upwardly towards said deck and a fluid flow position in which said elongate segment extends along the bed of a body of water and said connecting segment is aligned with said lower end of said first conduit to permit coupling of said first and second conduits.

2. A marine structure as claimed in claim 1 wherein said mounting means for mounting said first conduit comprises releasable clamping members whereby release thereof permits limited longitudinal movement of said first conduit into engagement with the aligned connecting segment of said second conduit in said fluid flow position.

3. A marine structure as claimed in claim 1 or claim 2 including releasable clamps operable releasably to clamp said elongate segment of said second conduit in said provisional position to said marine structure prior to pivotal movement into said fluid flow position.

4. A marine structure as claimed in any one of claims 1 to 3 including coupling means associated with the lower end of said first conduit and with said connecting segment of said second conduit, said coupling means being operable from a remote position to couple said conduits together when aligned.

5. A marine structure as claimed in any one of claims 1 to 4 including guide means secured to said marine structure and arranged to receive and locate said second conduit as it is pivoted into said fluid flow position with said connecting segment in alignment with said first conduit.

6. A marine structure as claimed in any one of claims 1 to 5 wherein said structure comprises a plurality of said support columns having a plurality of lateral braces extending therebetween, said first conduit being mounted to said lateral braces.

7. A marine structure as claimed in claim 6 wherein said pivot means comprises a pivot pin secured to said connecting segment and a pivot block secured to one of said braces.

8. A method of providing a marine structure with a fluid flow conduit extending from a deck thereof to the lower end thereof and in fluid flow connection with a fluid flow conduit extending along the bed of a body of water, comprising providing said marine structure with said first fluid flow conduit mounted thereto for limited movement, providing said marine structure with a pivotally mounted second fluid flow conduit comprising a connecting segment and an elongate segment, pivotally moving said second conduit away from a provisional position in which said elongate segment extends upwardly towards said deck into a fluid flow position in which said elongate segment extends along the bed of a body of water and said connecting segment is aligned with said lower end of said first conduit, and coupling said first and second conduits together.

9. A method as claimed in claim 8 including securing lengths of conduit to said elongate segment as said second conduit is pivotally moved down to the bed of the body of water.

10. A method as claimed in claim 9 including progressively supporting and lowering said second conduit and said lengths into a

submerged position as further lengths of conduit are secured thereto.

11. A method as claimed in claim 8 and substantially as described herein with reference to the accompanying drawings.

12. A marine structure substantially as described herein with reference to the accompanying drawings.