Wells – Processes – Separating material entering well
Patent
1997-08-20
1999-03-09
Tsay, Frank S.
Wells
Processes
Separating material entering well
166357, E21B 4301, E21B 4334
Patent
active
058788140
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method for offshore production of liquefied natural gas, wherein natural gas is supplied from an underground source to a production plant, the gas being transferred under a high pressure from the production plant to a LNG tanker, the transfer taking place through a pipeline surrounded by sea water, and wherein the high pressure gas is supplied to a conversion plant provided on the LNG tanker and arranged to convert at least a part of the gas to liquefied form by expansion of the gas, and the so liquefied gas is transferred to storage tanks on board the tanker.
Further, the invention relates to a system for offshore production of liquefied natural gas, comprising a production plant to which natural gas is supplied from an underground source, and a pipeline surrounded by sea water for transfer of gas under a high pressure from the production plant to a LNG tanker, the LNG tanker comprising a plant for conversion of at least a part of the gas to liquefied form by expansion of the gas, and storage tanks for storage of liquefied gas on the tanker.
BACKGROUND OF THE INVENTION
A method and a system of the above-mentioned type are known from U.S. Pat. No. 5,025,860. In the known system, the natural gas is purified on a platform or a ship and is thereafter transferred in compressed and cooled form via a high-pressure line to a LNG tanker where the gas is converted to liquefied form by expansion. The liquefied gas is stored on the tanker at a pressure of approximately 1 bar, whereas non-liquefied residual gases are returned to the platform or ship via a return line. The high-pressure line and the return line, which extend through the sea between the platform/ship and the LNG tanker, at both ends are taken up from the sea so that the end portions of the lines extend up from the water surface through free air and at their ends are connected to respective treatment units on the platform/ship and the LNG tanker, respectively.
With this transfer arrangement the high-pressure line and the return line will be subjected to external influences of different kinds under the different operational conditions which may occur in practice. Difficult weather conditions with storms and high waves will place clear limitations on the system operation, as both security reasons and practical reasons will then render impossible disconnection of the lines from a LNG tanker having full loading tanks, and connection of the lines to another, empty LNG tanker. Under such weather conditions it will also present problems to keep the LNG tanker in position so that it does not turn or move and interferes with the lines. In addition, in arctic waters the lines may be subjected to collision with icebergs or ice floes floating on the water.
In offshore production of hydrocarbons (oil and gas) it is known to make use of production vessels which are based on the so-called STP technique (STP=Submerged Turret Production). In this technique there is used a submerged buoy of the type comprising a central bottom-anchored member communicating with the topical underground source through at least one flexible riser, and which is provided with a swivel unit for the transfer of fluid to a production installation on the vessel. On the central buoy member there is rotatably mounted an outer buoy member which is arranged for introduction and releasable securement in a submerged downwardly open receiving space at the bottom of the vessel, so that the vessel may turn about the anchored, central buoy member under the influence of wind, waves and water currents. For a further description of this technique reference may be made to e.g. Norwegian laying-open print No. 176 129.
Further, in offshore loading and unloading of hydrocarbons it is known to use a so-called STL buoy (STL=Submerged Turret Loading) which is based on the same principle as the STP buoy, but which has a simpler swivel means than the STP swivel which normally has several through-going passages or courses. For a further description of this buoy struc
REFERENCES:
patent: 4067202 (1978-01-01), Reed
patent: 4433940 (1984-02-01), Harrison
patent: 4632603 (1986-12-01), Baugh
patent: 4826354 (1989-05-01), Adorjan
patent: 4892495 (1990-01-01), Svensen
patent: 4991614 (1991-02-01), Hammel
patent: 5025860 (1991-06-01), Mandrin
patent: 5431589 (1995-07-01), Corona
Breivik Kare
Fredheim Arne Olav
Paurola Pentti
Den Norske Stats Oljeselskap A.S.
Tsay Frank S.
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