Deep-water Subsea Wellhead-casing System Lateral Stability Analysis

As the deep-water drilling wellhead and casing string system joins BOP and soil,so the analysis of its lateral stability is very meaningful to design the casing string.Currently most of the analyses of the static and dynamic performance of the wellhead and casing strings do not consider the influence of gravity,the majority of the models built simplify the soil as string and dashpot which ignore the continuity of the soil.The paper considers the gravity,the top moment,the friction of soil and the nonlinear soil reaction computed by p-y curve method to deduce the nonlinear static control differential equations of the stings system by static balance method and principle of potential energy method,and deduce the nonlinear dynamic control equation by Hamilton principle.Using Newmark method to resolve the dynamic equation and analyze the change of pipe parameters.Using the common finite element analysis software ABAQUS to simulate the example and test the correctness of the theoretical analysis.Analysis the influence factors of the pipe strings stability which conclude the moment on the wellhead,pipe size,the height of cement and the distance between wellhead and the mudline.