Patent ID: 6302048
Filing Date: 2001-10-16
Classification: B63B,E21B

Abstract:
A swivel device for a ship used for the exploitation of hydrocarbon wells in the seabed by means of drill pipe strings and risers, said ship being formed with a vertical shaft extending through the hull of the ship, said swivel device comprising:a turret having a substantially vertical axis, said turret being rotationally supported in the shaft so that said shaft can rotate relative to said turret to allow the ship to move about said vertical axis responsive to environment conditions to which it is subjected, said turret having an internal surface, the internal surface of said turret being provided with substantially vertical bar-like members extending from said internal surface, each of said bar-like members engaging a mooring chain, certain of said bar-like members, at the lower ends thereof, carrying an attachment hook for a mooring chain of fixed length, others of said bar-like members, at the lower ends thereof, carrying a guide pulley for a mooring chain, the length of which can be varied, said turret having a locking device for locking a variable length chain to said turret;a first pipe positioned in said turret substantially concentrically therewith with respect to said vertical axis and connected to said turret by means of said bar-like members, said internal surface of said turret facing an external surface of said first pipe, said internal surface of said turret being spaced from said external surface of said first pipe along said surfaces to form a vertically through going annular passage for accommodating at least one riser; anda second pipe connected to said first pipe and positioned in said first pipe substantially concentrically therewith so that an internal surface of said first pipe is spaced from and faces an external surface of said second pipe, said second pipe having a central through going bore for accommodating a string of drill pipe separately from said at least one riser, said second pipe, at a lower end along said vertical axis, being formed with a pipe wall portion widening in a downward direction and adapted to receive a buoy.