US3082608A

US3082608A - Marine platform

Info

Publication number: US3082608A
Application number: US70155A
Authority: US
Inventors: Daniell Alan Francis
Original assignee: INTERCONTINENTAL MARINE DEV LT
Current assignee: INTERCONTINENTAL MARINE DEV LT; INTERCONTINENTAL MARINE DEVELOPMENT Ltd
Priority date: 1960-05-30
Filing date: 1960-11-18
Publication date: 1963-03-26
Anticipated expiration: 1980-03-26

Description

March 26, 1963 A. F. DANIELL 3,082,608

MARINE PLATFORM Filed Nov. 18, 1960 3 Sheets-Sheet 1 15 FIG. 2. i5

14 14 ENTZDg 1 v ATTORNEYS March 26, 1963 A. F. DANIELL 3,082,608

MARINE PLATFORM Filed Nov. 18, 1960 s Sheets-Sheet 2 INVENTOR BY 2 QM WJIWWIZMMYZYA ATTORNEYS March 26, 1963 A. F. DANIELL 3,

MARINE PLATFORM Filed Nov. 18, 1960 3 Sheets-Sheet 5 ATTORNEYS United States Patent 3,632,668 MARENE PLATFORM Alan Francis Daniell, London, England, assignor to Intercontinentai Marine Development Limited, London, England, a British company Filed Nov. 18, 1969, Ser. No. 70,155 Claims priority, appiication Great Britain May 30, 1960 4 Claims. (Cl. 61-465) The subject of the present invention is a marine platform which may be used as a marine drilling platform for petroleum prospecting, as a shipping terminal for tankers fed by submarine pipe lines, or for any other use and has for its object to provide a platform which will remain precisely in position under the effects of tide, waves or wind and which can be used in depths of water where a platform supported by piles would be expensive or impracticable.

In accordance with the invention the platform is formed with a substructure having a high reserve of buoyancy adapted to be held in submerged condition at a depth unaffected by wave or tide motion by means of a series of spaced anchorages located on the seat bottom and connected with the substructure by a series of taut chains or wire cables holding the structure substantially horizontal.

Preferably the substructure is triangular in plan and obtains the major part of its buoyancy from large diameter tubes forming a triangular frame. The upper structure is designed to suit individual requirements and is so arranged as to offer minimum resistance to Waves and wind. The platform is attached by wire cables or chains to heavy mooring clumps arranged in triangular form. As the platform when partially submerged will have a large reserve of buoyancy all the mooring wires or chains are subjected to tension and therefore act as a rigid tri-' angulated structure. Providing that the weights of moorings and the buoyancy of the platform are properly proportioned no slackening of the mooring wires or chains occurs in loads from wave action wind or incidental loading so that the only movement of the platform is that due to elastic extension of the mooring cables or chains and is thus negligibly small. Each mooring preferably consists of a heavy vessel containing a buoyancy chamber connected by compressed air lines to the platform so that the moorings may be floated up by admitting compressed air and blowing ballast water when it is required to move'the rig. The horizontal component of the mooring forces is resisted by laying the chain cables to the length required to suit the particular conditions. The platform itself and the moorings can therefore be readily towed from site to site and established at a new position rapidly and without need for any outside equipment.

The accompanying drawing illustrates schematically a preferred form of the invention, FIG. 1 being an elevation of the platform in operative position, FIG. 2 a plan view and FIG. 3 a perspective view thereof. FIG. 4 is an elevation and FIG. 5 a plan view showing the preferred form of mooring clump, while FIG. 6 shows in diagram form an arrangement of flotation devices attached to the mooring cables, and serving, where the rig is located in deep water, to reduce the spring of the mooring cables due to the catenary effect.

As shown, the platform 10 is formed with a substructure 11 having a high reserve of buoyancy derived from large diameter tubes 12 forming a triangular frame. The platform is attached by wire cables or chains 13 to heavy mooring clumps 14 which are in turn anchored by chains 15 to heavy anchorages 15a, the cables extending from the moorings being connected to the sides of the 3,982,6li8 Patented Mar. 26, 1963 substructure in such manner angles.

Consequently when the platform is partially submerged due to the large reserve of buoyancy of the substructure, the mooring cables are subjected to tension and therefore act as a rigid triangulated structure.

The minimum depth of water to obtain satisfactory angles on the moorings is of the order of ft., and the maximum depth is limited only by the practicable difliculties of handling great lengths of mooring wires.

A typical platform of ft. side would have an excess buoyancy of the order of 400 tons when carrying tons of deck equipment and would withstand a horizontal force of about 200 tons without slackening of any cable and therefore without appreciable movement.

As indicated in FIGS. 4 and 5, the lines of the mooring chains 13 and the anchor chains 15 should intersect at or adjacent the centre of gravity 16 of each clump 14. Two anchor chains 15 should be provided for each clump 14 and should extend at an angle of about 20 to one another. As indicated, the clumps 14 may be provided with flaring pockets 16a to receive the ends of the anchor chains 15 and with leads 17 for the mooring cables 13.

Where the rig is located in deep water, say 300 feet and upwards, in order to reduce the catenary effect it may be necessary as shown in FIG. 6 to provide flotation devices such as hollow steel spheres 18 fixed at intervals by cables 19 along the mooring cables 13.

I claim:

1. A marine platform including a buoyant structure comprising a sub-structure incorporating hollow tubular side members arranged end-to-end in polygonal formation, a single mooring clump for each hollow tubular side member, means connect-ing each mooring clump to an associated side member at points near the ends thereof, and spaced anchors connected to each mooring clump, said anchors being connected to its associated mooring clump by chains, the chains connecting the anchors to their associated mooring clumps and the means connecting each associated mooring clump to the respective associated sides of the sub-structure extending in lines which intersect adjacent the center of gravity of the respective clumps.

2. A marine platform including a buoyant structure comprising a sub-structure incorporating large diameter hollow tubular side members arranged end-to-end in triangular formation, three submersible mooring clumps, means for respectively connecting the mooring clumps to the hollow tubular side members at points near the ends thereof thereby forming a triangulated structure, and spaced anchors connected to each mooring clump, said anchors being connected to its associated mooring clump by chains, the chains connecting the anchors to their associated mooring clumps and the means connecting each associated mooring clump to the respective associated sides of the sub-structure extending in lines which intersect adjacent the center of gravity of the respective clumps.

3. A marine platform including a buoyant structure comprising a generally polygonal sub-structure, a single mooring clump for each side of said sub-structure, means connecting each mooring clump to an associated side of said sub-structure at points near the ends thereof, spaced anchors for said mooring clumps, and means connecting each of said anchors to an associated clump, the means connecting the anchors to their associated mooring clumps and the means connecting each associated mooring clump to the respective associated sides of the sub-structure extending in lines which intersect adjacent the center of gravity of the respective clumps.

as to form a series of tri- 4. A marine platform as defined in claim 3 in which the sub-structure -is generally triangular in shape.

References Cited in the file of this patent UNITED STATES PATENTS Vick Nov. 3, 1914 Armstrong May 7, 1946 4 Ault Feb. 8, 1955 Reeve Apr. 14, 1959 Marsh Oct. 13, 1959 Schurman June 7, 1960 Ludwig June 6, 1961 Nesbitt May 1, 1962

Claims

1. A MARINE PLATFORM INCLUDING A BUOYANT STRUCTURE COMPRISING A SUB-STRUCTURE INCORPORATING HOLLOW TUBULAR SIDE MEMBERS ARRANGED END-TO-END IN POLYGONAL FORMATION, A SINGLE MOORING CLUMP FOR EACH HOLLOW TUBULAR SIDE MEMBER, MEANS CONNECTING EACH MOORING CLUMP TO AN ASSOCIATED SIDE MEMBER AT POINTS NEAR THE ENDS THEREOF, AND SPACED ANCHORS CONNECTED TO EACH MOORING CLUMP, SAID ANCHORS BEING CONNECTED TO ITS ASSOCIATED MOORING CLUMP BY CHAINS, THE CHAINS CONNECTING THE ANCHORS TO THEIR ASSOCIATED MOORING CLUMPS AND THE MEANS CONNECTING EACH ASSOCIATED MOORING CLUMP TO THE RESPECTIVE ASSOCIATED SIDES OF THE SUB-STRUCTURE EXTENDING IN LINES WHICH INTERSECT ADJACENT THE CENTER OF GRAVITY OF THE RESPECTIVE CLUMPS.