Patent ID: 7975769

Claim:
Hydrocarbon exploration system, comprising: a first vessel ( 1 ) having a turret ( 3 ) around which the vessel can weathervane, the turret being moored to the sea bed, and a second vessel ( 7 , 8 ) connected with at least one riser ( 12 ) to a subsea well ( 5 , 6 ), the first vessel being connected to the second vessel via a fluid transfer duct ( 20 , 21 ) comprising a first end section ( 23 ) attached to the turret ( 3 ) of the first vessel ( 1 ), a substantially horizontal mid section ( 24 ), and a second end section ( 22 ) attached at or near the second vessel ( 7 , 8 ), the fluid transfer duct extending at a depth between 30 m and 300 m below water level, and comprising a central buoyancy tank ( 64 ), a frame ( 63 ) attached to the tank carrying a number of flow lines ( 60 , 61 ) and a power supply cable ( 39 , 40 ), an anchor line ( 31 ) connecting the central buoyancy tank to the sea bed, wherein the second vessel ( 7 , 8 ) has no large hydrocarbon storage facilities and a hull weight of between 2,000 and 15,000 tons and comprises an upper structure ( 13 ) and a submerged base ( 15 ) to which second vessel ( 7 , 8 )) the riser ( 12 ) is connected, the base ( 15 ) being attached to the sea bed via taut tendons ( 9 , 10 ), the weight exerted by the fluid transfer duct ( 20 , 21 ) on the second vessel ( 7 , 8 ) being below 1,000 ton, a power generator ( 35 ) being situated on the first vessel ( 1 ), wherein power is transferred from the power generator ( 35 ) via an electrical swivel ( 38 ) on the first vessel, to the power supply cable, the power supply cable ( 39 , 40 ) extending along the flow lines ( 60 , 61 ) from the first vessel ( 1 ) to the second vessel ( 7 , 8 ), and being supported at least partly by the frame ( 63 ), and wherein at least one further said second vessel ( 7 , 8 ), is attached to the first vessel ( 1 ) via a respective said fluid transfer duct ( 20 , 21 ).