The suction mooring, a new type of offshore single point mooring
Existing systems for mooring offshore oil production vessels of the ship type only permit the mooring or tying up of the vessel in quite low wave conditions. Virtually all existing systems do not permit the vessel to moor in wave conditions exceeding H{sub s} = 4.5 m. The wait for the waves to subside following the storm causes additional production losses due to the oil field being shut in. A newly developed mooring system, the suction mooring, promises to overcome this problem by permitting the mooring of the vessels in wave heights to at least H{sub s} = 8 m. The principle of the mooring consists of using the hydrostatic pressure available at the keel of the vessel to press a mooring buoy onto the bottom and holding the vessel by the resulting friction. The action of the mooring buoy is similar to that of a suction cup. The pressure above the buoy is lowered and maintained low by means of pumps aboard the vessel. This paper reports on model tests carried out to prove the feasibility of conducting the mooring operations in high waves. Three different configurations of the mooring buoy were tested. For two of the configurations it was found that the mooring process could be carried out safely in all wave heights tested i.e. up to H{sub s} = 7.7 m. The impact upon offshore operations of this capability was investigated by performing Monte Carlo simulations on a hypothetical oil field in the center North Sea and in the northern North Sea. An actual center North Sea wave record was used in the simulations. The suction mooring system was compared to two other high performance mooring systems. The results show that weather related oil field shut-ins are reduced an order of magnitude by application of the suction mooring compared to the other systems simulated.
- OSTI ID:
- 128882
- Report Number(s):
- CONF-950501-; TRN: IM9550%%268
- Resource Relation:
- Conference: 27. offshore technology conference, Houston, TX (United States), 1-4 May 1995; Other Information: PBD: 1995; Related Information: Is Part Of 27. Annual Offshore Technology Conference: 1995 Proceedings. Volume 2: Platform and marine system design; PB: 986 p.
- Country of Publication:
- United States
- Language:
- English
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