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US 7,011,473 B2Granted
Method for underwater transportation and installation or removal of objects at sea
AssigneeAker Marine Contractors AS
InventorsGunnar Tangen, Lars Hvam
Life of this patent
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AssigneeAker Marine Contractors AS
InventorsGunnar Tangen, Lars Hvam
Estimating the term…
Method for transport and installation of objects at sea, particularly relating to transport and installation of obs jects that are part of the infrastructure in oil and gas fields offshore, the object (4) is put in the sea at a suitable location near the shore or in sheltered waters, then towed to the installation site while being suspended in a slender buoyancy unit (5) acting much like a heave compensating unit. Upon arrival at the installation site, the suspension of the object (4) is transferred from the buoyancy unit (5) to a heave compensated winch (3) on a surface vessel (2), preferably the same vessel as used for the preceding towing operation. The winch is used to lower is the object (4) to its destination on the sea bottom or a predetermined location above the sea bottom.
A method for transport and installation of objects at sea, particularly relating to transport and installation of subsea objects that are part of the infrastructure in oil and gas fields offshore, where the object is put in the sea at a suitable location near the shore or in sheltered waters, then towed to the installation site while being suspended via a suspension arrangement of a predetermined length in at least one floating buoyancy unit, and subsequently lowered to its final destination, wherein use is made of at least one slender upright buoyancy unit, which also is used as a heave compensator during the towing and thereby reduces the dynamic loads in the towed object and the suspension arrangement between the towed object and the buoyancy unit, and that upon arrival at the installation site, the suspension of the object is transferred from said at least one buoyancy unit to a heave compensated winch on a surface vessel while the buoyancy unit is disconnected, said winch being used to lower the object to its destination on the sea bottom or a predetermined location above the sea bottom.
A method for removal and transport of objects at sea, particularly relating to removal and transport of objects that are part of the infrastructure in oil and gas fields offshore, where the object is recovered from the seabed or a position between the seabed and sea surface, with subsequent tow to a predetermined place, wherein the object is raised to a predetermined distance below the surface by means of a winch on a surface vessel, whereupon the suspension of the object is transferred via a suspension arrangement of a predetermined length to at least one floating buoyancy unit before the tow is started, wherein use is made of a heave compensated winch during the raising, and further that use is made of a slender upright buoyancy unit, which is also used as a heave compensator during the towing and thereby reduces the dynamic loads in the towed object and the suspension arrangement between the towed object and the buoyancy unit.
Dependencies are inferred from the claim text.