| 摘要 |
A coiled tubing lift frame assembly for use as a back-up heave compensator on a floating vessel is described. The assembly includes a frame having an upper frame section adapted for attachment to a top drive system and a lower frame section adapted to interface with a flowhead assembly. The assembly also includes a pair of hydraulic cylinders spaced apart from one another, the hydraulic cylinders having a respective cylinder barrel and a piston rod translatable therein with free end of the piston rods being fixed to the upper frame section. The assembly also includes a piston accumulator disposed adjacent to a first of the hydraulic cylinders and in fluid communication therewith via a hydraulic fluid line and an air accumulator disposed adjacent to a second of the hydraulic cylinders and in fluid communication with the piston accumulator via a pneumatic fluid line. In back-up mode, the piston rods in the cylinders remain stationary at a mid-stroke position when an axial load on the riser is within a predetermined range of operating loads. The piston rods extend on an upheave of the floating vessel when the axial load exceeds a predetermined upper operating load threshold and retract on a down heave of the floating vessel when the axial load falls below a predetermined Iower operating load threshold. |
