Patent NO-343296-B1 (NO)
Title: Mobile wireline compensator
Inventor: MARTINSEN TORD
IPC: B66D1/52
Filed: 2016-12-30
Abstract: Mobile wireline compensator (100) for reduction ofdynamic loads and motion in offshore liftingoperations based upon a horizontal actuator (10)comprising:- a passive actuator cylinder (30), comprising a thirdpiston (31) connected to a piston rod (32), and hastwo volumes, designated V1 and V2, where V1 ison the piston side and V2 is on the rod side, thevolumes are filled differently, depending on if thepassive actuator cylinder (30) is working in tension or compression mode, where V1 is filled with hydraulic fluid and is connected to a gas accumulator (40) via conduit means and V2 is either filled with oil or filled with low pressure gas (including vacuum) when working in compression mode and where V2 is filled with hydraulic fluid and is connected to a gas accumulator (40) via conduit means and V1 is either filled with oil or filled with low pressure gas (including vacuum) when working in tension mode- an active actuator cylinder (20), including a piston rod (21), and the passive actuator cylinder (30) have collinear longitudinal axes that are horizontal, where their respective piston rods (21, 32) are fixed together in a stiff connection with actuator sheaves (14, 15) at the connection point- a position measurement means (33) to register the position of the third piston (31)- a gas accumulator (40), featuring a fourth piston (41) that separates fluid, containing two volumes designated V6 and V7, where V6 is connected to V1 in the passive actuator cylinder (30) if operating in compression mode and to V2 in the passive actuator cylinder (30) if operating in tension mode, via conduit means adapted with a control valve (CV1), filled with hydraulic fluid and where V7 is filled with gas- the actuator (10) further contains framework (11) joining the two actuator cylinders (20, 30) together in a stiff connection, where the framework (11) may partly consist of tanks and accumulators to reduce weight, the framework (11) is further fitted with connection means (12) used to connect the MWC (100) to a crane, or similar, located on a vessel (102), where the connection means (12) may be located in the centre of gravity of the MWC (100) or at other locations, the framework (11) further supports three secondary sheaves (17, 19a, 19b), used to support rope means (16, 18), such as steel wire rope, fibre rope, belt, chain or similar, connecting the actuator sheaves (14, 15) to the lower connection means (12), which in turn is connected to the payload (101), the rope means (16, 18) are reeved over the actuator sheaves (14, 15) and the secondary sheaves (17, 19a, 19b), with one end connected to a fixed point, such as the framework (11) and the other end connected to the payload (101) via a lower connection means (12), lowering of the payload (101) relative to the MWC (100) causes the actuator sheaves (14, 15) to move horizontally, the direction (i.e., towards or away from the active actuator cylinder (20)) depending on if the MWC (100) is compression- or tension-based- an accelerometer integrated into the MWC (100), adapted for measuring vertical motion- communication means, such as wireless communication while in air and acoustic communication while submerged, adapted for transmitting data from the vessel (102), such as commands and winch spooling speed, to the MWC (100)- a hydraulic motor (P), which is reversible, adapted to actuate the active actuator cylinder (30), based on measurement data from the position sensor (33), the accelerometer and the measurement data from the vessel (102), such as winch spooling speed.