An apparatus for supporting an element from a floating marine platform

摘要

1,092,247. Wells &c. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. Sept. 16, 1965 [Sept. 18, 1964], No. 39579/65. Heading E1F. The effect of the vertical movement of a floating platform on an element supported by the platform is compensated by apparatus comprising means to measure the vertical movement, and an actuating device coupled to or forming part of the measuring means and causing vertical movement of the element in response to vertical movement of the platform. A drilling vessel 10 supports a manipulator 20 adjacent a wellhead 15 by means of a line 21 passing over a pulley 23. A line 36 is anchored to the sea bed and runs around a drum 25 which is connected by a line 24 to the pulley 23. The drum is subjected to a constant torque sufficient to support the manipulator and keep the line 36 in tension so that increase or decrease of the distance of the vessel from the bed is accompanied by corresponding lowering or raising of the manipulator relative to the vessel. The constant torque is derived from the actuating device comprising a hydraulic cylinder 31 which is supplied with pressure fluid from a compressed air tank 32. In a modification (Fig. 2, not shown) the vertical movement is measured by an anchored line (71) which is connected to a transducer (66) generating electrical signals according to the length of the line, the signals being supplied to a controller (67). The signal from the controller actuates a control valve (61) to supply fluid to or exhaust fluid from one end of the actuating device 51, the other end of the actuating device being supplied with fluid under pressure sufficient to support the element (44) which is a drill pipe supported by the free end of the hoisting cable which is attached to the rod of the actuating device. A device (68) detects the position of the rod to send a signal to the controller to stabilize the system.