Device for compensation of wave influenced distance variations on a drill string

摘要

Device (11) for compensation of wave induced distance variations to a drill string between a floating drill rig and a seabed-fixed installation, comprising an extendable cylinder/piston unit (12) which is arranged to be able to compensate when the load exceeds a pre-determined threshold value. The cylinder (13) of the cylinder/piston unit (12) comprises a non-compressible liquid at both sides of a piston (14) positioned substantially in the middle of the cylinder (13) and is prevented from fluid communication with the surroundings. A control valve (19) is arranged to activate the device (11) by opening for fluid communication between the cylinder (13) and a gas containing accumulator (17) when the load exceeds a predetermined threshold value. The device is characterized by being a complete, self-supported unit comprising cylinder (13), piston (14) on a piston rod (15), accumulator (17), control valve (19) and drainage tank (20).

主权项

1. A device for compensation of wave induced distance variations to a drill string between a floating drill rig and a seabed-fixed installation, comprising an extendable cylinder/piston unit (12) configured to be able to compensate when the load exceeds a pre-determined threshold value, the cylinder/piston unit (12) including a reciprocable piston (14) within a coaxial longitudinally extending cylinder (13) with a non-compressible liquid at both longitudinal sides of a piston (14), the piston (14) positioned substantially in the longitudinal middle of the cylinder (13) and being prevented from fluid communication with the surroundings in the base position, wherein at least one control valve (19) is arranged between the cylinder (13) and at least one gas containing accumulator (17) for activating the device (11) into an activated position by opening to allow fluid communication between the cylinder (13) and the at least one gas containing accumulator (17) when the load exceeds a pre-determined threshold value, the device (11) being a complete self-supported unit and a closed system during regular operation comprising the cylinder (13), the piston (14) on a piston rod (15), the accumulator (17), the control valve (19) and a drainage tank (20).