Design of flexible hang-off device of riser based on dynamic loading compensation

To solve the safety problem of riser during operation while avoiding typhoon on a drilling platform, the paper proposes a system scheme for the new-type flexible hang-off of the riser equipped with active compensation function in view of limitations and advantages of the current soft hang-off and hard hang-off technologies. Based on using the traditional hard hang-off device, a hydraulic cylinder with motion compensation and a stroke increasing system are set up to minimize the dynamic load of riser using the limited compensation stroke. Further, this paper proposes two compensation schemes, i.e., displacement compensation in proportion and acceleration peak clipping method, then carries out a comparative research on their applicability. and establishes the Simulink simulation model to perform a system simulation analysis. The computational analysis shows that the proposed system scheme of flexible hang-off for riser has good dynamic loading compensation function, and the acceleration peak clipping method is superior to the displacement compensation in proportion.