Recoil Response Analysis of Emergency Disconnection of Deepwater Drilling Riser Using Vector Form Intrinsic Finite Element (VFIFE) Method

Deepwater drilling riser is the key passage connecting the offshore platform to the subsea wellhead in offshore drilling procedure, and the safe implementation of riser emergency disconnection helps to avoid marine accidents in extreme weather. The Vector Form Intrinsic Finite Element (VFIFE) method has been applied to the static analysis and deformation analysis of marine buried pipelines, which proves the reliability of this method. In this paper, using VFIFE method, the motion point equations of riser and emergency disconnection model are given considering the effects of mud discharge in riser, the heave motion of offshore platform and the nonlinear stiffness of direct-acting tensioner (DAT). The sensitivity analysis of riser recoil in different disconnection phase angles, fluid density in riser and vibration amplitude of offshore platform is also given respectively. The numerical simulation results show that with the increase of fluid density in the riser, the heave amplitude of the offshore platform increases, and the riser is more likely to collide with the subsea wellhead during emergency disconnection. Choosing the appropriate disconnection phase angle helps to avoid collision between riser and subsea wellhead.