软悬挂状态下隔水管动力特性分析

Dynamic mechanical behavior analysis of drilling riser under soft hang-off condition

建立了软悬挂状态下隔水管动力分析模型,采用有限单元法对模型进行离散,结合Newmark-β法对动态方程求解,并对模型进行验证,最后选取南海某口深水井实际参数,对软悬挂状态下隔水管动力特性进行分析。研究结果表明:软悬挂状态下隔水管底端横向位移最大,顶部铰接处弯矩最大。软悬挂状态下,隔水管横向位移与弯矩随着海底隔水管总成(LMRP)重量增加而减小,随着平台运动速度、平台航向与海流方向夹角增大而增大;回收隔水管减小悬挂长度有利于减小最大横向位移,但会造成弯矩轻微增加;采用旋转刚度适当较大的挠性接头则有利于减小隔水管挠性接头以下整体位移与弯矩。研究成果为钻井平台避台撤离时隔水管的安全提供理论指导。

A dynamic analysis model of soft hang-off riser is established,and finite elment method and Newmark-βmethod are applied to solve the governing equation.The result of our analysis model is verdified by other softs.Then,a deep water drilling well in the South China Sea is selected to analyse the dynamic behavior of soft hang-off riser.The result shows that the lateral displacement at the bottom end of the riser is the largest in the soft suspension evacuation state,but the bending moment is small.The bending moment at the top of the riser reaches the greatest.The lateral displacement and bending moment of the soft hang-off riser decreases as the weight of the LMRP increases,increases as the speed of the platform increases,increases as the angel between the platform and current increases.Recycle parts of the riser to ruduce the hang-off length are benifical to reducing the lateral displacement but slightly increase the bending moment.A larger rotation stiffness of the rotation joint can reduce the lateral displacement and the bending moment of the lower parts.The research results can provide theoretical guidance for the safety of the hang-off riser when the drilling platform evacuates for avoiding the typhoon.