Buoys – rafts – and aquatic devices – Buoy – For mooring a vessel
Patent
1999-10-11
2000-12-19
Swinehart, Ed
Buoys, rafts, and aquatic devices
Buoy
For mooring a vessel
114 74R, 114 77R, B63B 2202
Patent
active
061621056
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a two-part vessel for use in oil transport in waters where ice may occur.
SUMMARY OF THE INVENTION
The object of the invention is to provide a two-part vessel of said type which enables an optimal utilization and simultaneously covers the needs for see oil transport, supply and stand-by services, together with ice breaking in arctic waters.
According to the invention the above-mentioned object is achieved in that the vessel comprises a first part in the form of a barge part containing a number of cargo tanks and having a bow portion having a submerged receiving space for a mooring and loading buoy, and a second part in the form of a propulsion part having a stern portion which is designed for breaking of ice, the second part with its forward end being arranged for connection to the stern portion of the barge part.
The barge part of the vessel according to the invention especially is intended for anchoring by means of a buoy of the so-called STL type, where "STL" stands for "Submerged Turret Loading". A buoy of this type is a submerged buoy comprising a central bottom-anchored member communicating with the topical source or installation via at least one flexible riser, and which is provided with a swivel unit for the transfer of oil (or gas) to storage tanks on the topical vessel. On the central buoy member there is rotatably mounted an outer buoy member which is adapted for introduction and releasable securing in a submerged, downwardly open receiving space at the bottom of the vessel, so that the vessel can turn about the anchored central buoy member under the influence of prevailing environmental forces, such as ice, wind, waves and water currents. For a further description of the STL system and the associated buoy structure reference can be made to e.g. US patent publication No. 5 564 957.
When using the two-part vessel according to the invention, an STL-barge will be brought out to the topical oil-producing field by means of a connected propulsion part, and will be anchored to an STL buoy when arriving at the field. The barge may be equipped with a remotely controlled pick-up or so-called ROP (Remotely Operated Pick-up) in order to avoid problems with a floating "messenger" or pick-up line which is connected to the submerged buoy. At the oil field there may be installed two STL loading buoys, it being then possible to load directly to several barges. Loading by means of such a system is called "Direct Shuttle Loading" (DSL). DSL eliminates the need for permanent storage tanks at the field, and can give substantial savings.
The propulsion part of the two-part vessel preferably is provided with the necessary installations in order also to be able to function as a supply vessel. This contributes to the fact that the two parts or units of the vessel can be utilized in an optimal manner for the necessary operations, something which totally seen gives an optimal economy.
The propulsion part of the vessel preferably is provided with propulsion equipment which is suitable for operation of the propulsion part in the pulling as well as the pushing mode. In waters without ice the two-part vessel normally is driven forwards with the barge part in front. In ice-bound waters, however, the vessel preferably is driven forwards with the propulsion part first, the ice breaker function thereof being utilized. In addition to this ice breaker function the propulsion part, as mentioned, also has a supply and stand-by function. With a view to the different functions, the propulsion part can be designated "Ice Breaker Supply Tug" or IBST. When the IBST vessel has brought a fully-loaded barge unit to a loading harbour, the IBST vessel can take on board a new load at the same time as the barge unit is unloaded. Power for load-transferring pumps will, with disconnected IBST, be able to be delivered from the land terminal. The propulsion part may possibly also be used as a supply ship for drilling and production platforms.
In an advantageous embodiment of the two-part vessel acc
REFERENCES:
patent: 3525312 (1970-08-01), Beck
patent: 3557741 (1971-01-01), Teasdale
patent: 3614938 (1971-10-01), Statile
patent: 3633532 (1972-01-01), Bruce
patent: 4759307 (1988-07-01), Scott
patent: 5558036 (1996-09-01), Hara
patent: 5660131 (1997-08-01), Gulling et al.
Browning Clifford W.
Den Norske Stats Oljeselskap A.S.
Swinehart Ed
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