Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,... – Submerging – raising – or manipulating line of pipe or cable...
Patent
1996-05-03
1997-12-16
Graysay, Tamara L.
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
Submerging, raising, or manipulating line of pipe or cable...
166345, 141279, B65B 308, F16L 114
Patent
active
056977328
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a system for offshore production of hydrocarbons by means of a vessel arranged for quick connection to and disconnection from a submerged buoy, wherein the buoy comprises an outer buoyancy member for introduction and releasable securing in a submerged downwardly open receiving space in the vessel, and a centre member rotatably mounted in the outer member and anchored to the sea bed and further connected to at least one riser extending up to the buoy, and wherein a swivel device is arranged at the upper end of the buoy for connection and transfer of process fluid between the risers and a tube system on the vessel.
Different systems of the above-mentioned type are disclosed in the Norwegian patent applications Nos. 922043,922044 and 922045. These systems are based on the so-called STL system (STL =Submerged Turret Loading) which is disclosed i.a. in the international patent application No. PCT/NO92/00054. In this system a submerged buoy forms a collecting point for one or more flexible risers and umbilicals from e.g. a production system at the sea bed. The buoy is adapted to be raised and secured in the receiving space in the topical vessel, to establish a transport system for the petroleum products from the production system at the sea bed to cargo tanks in the vessel. When the buoy is secured in the receiving space, the vessel is rigidly fastened to the outer buoyancy member of the buoy and is rotatable about the centre member of the buoy which is anchored to the sea bed by means of a suitable anchoring system. Thus, the buoy itself constitutes a rotating body or turret about which the vessel is allowed to turn under the influence of wind, waves and water currents.
Adaptation of the STL system to the use on vessels for production of hydrocarbons involves a number of substantial economical and practical advantages. For a further description of these advantages reference is made to the above-mentioned Norwegian patent applications.
SUMMARY OF THE INVENTION
A general object of the present invention is to further develop a system of the introductorily stated type--which has a coupling means at the bottom of the vessel and avoids large deck-mounted structures--and to provide a system ensuring a quick connection and disconnection and giving maximum security for disconnection under all circumstances.
A further object of the invention is to provide a system having a coupling giving a secure sealing between the topical production fluids and their surroundings.
Another object is to provide a system wherein the coupling between buoy and vessel may be set with large clearances and with a minimal risk for damaging the coupling.
A further object is to provide a system giving the possibility for a simple monitoring of static and dynamic seals, there being used a barrier liquid having a higher pressure than the ambient pressure.
A further object of the invention is to provide a system which is suitable for remotely controlled operation of the swivel device and coupling means in connection therewith.
For the achievement of the above-mentioned objects there is provided a system of the introductorily stated type which, according to the invention, is characterized in that the swivel device comprises a female member and a male member which may be moved to engagement with each other, one member of the swivel device being permanently fastened to the centre member of the buoy and the other member of the swivel device being connected to an operating means on the vessel, so that the male and female members may be connected to and disconnected from each other by means of the operating means, the swivel members in the engaged condition defining common annular spaces communicating with associated fluid paths in the swivel members, and sealing means being provided on each side of the annular spaces, which sealing means, when activated, form a seal between the annular spaces, and can be relieved when mutually disconnecting the swivel members.
A particularly advantageous em
REFERENCES:
patent: 4102142 (1978-07-01), Lee
patent: 4478586 (1984-10-01), Gentry et al.
patent: 4604961 (1986-08-01), Ortloff et al.
patent: 4647076 (1987-03-01), Pollack et al.
patent: 4925219 (1990-05-01), Pollack et al.
patent: 5143483 (1992-09-01), Petersen
Den Norske Stats Oljeselskap A.S.
Graysay Tamara L.
Mayo Tara L.
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