中文摘要：

随着超深井、定向井、水平井、大位移井及大斜度井在石油钻井工程中的广泛应用，由井下复杂工况引起的钻杆接头过早失效问题日益突出，导致钻井周期增长，成本增加，成为制约钻井工程效益的主要因素之一.近年来，不少学者对钻杆接头进行了大量研究，多数采用二维轴对称模型，少数采用三维力学模型，但并未同时考虑螺纹升角和井眼弯曲作用等因素的影响，而钻杆接头的极限承载能力研究更是鲜见报道.针对上述问题，基于虚功原理、vonMises屈服原则及接触非线性理论，同时考虑螺纹升角和井眼弯曲作用，建立了钻杆接头的三维数值仿真模型与井眼曲率到加载弯矩的转换模型，研究了钻杆接头的上扣特性、井眼曲率对连接强度和密封性能的影响，考虑预紧力、弯曲载荷及动载安全系数，计算了钻杆接头的极限工作拉力和极限工作扭矩.研究结果表明：上扣扭矩使钻杆接头产生一定的初始接触压力，保证钻杆接头井下作业过程中的连接强度与密封性能；井眼曲率对钻杆接头井下作业过程中的连接强度与密封性能影响极大，常见的某些工况会导致钻杆接头的连接强度和密封性能丧失，考虑服役时的随机振动与冲击，常规的超深井、水平井、定向井、大位移井及大斜度井弯曲段钻杆接头的设计和选型应着重考虑井眼曲率的影响；针对设计的每种钻杆接头，都应考虑常见的井眼曲率和轴向拉伸载荷进行极限工作拉力和极限工作扭矩的精细化数值计算，以确保其安全工作.

英文摘要：

With the wide applications of the logging technologies of the ultra-deep well,the horizontal well,the directional well,the extended-reach well and the highly-deviated well in the petroleum drilling engineering,the premature failure of the drill pipe joint caused by underground complex working conditions becomes increasingly a prominent issue,and it results in the increase of the drilling period and the drilling cost,as well as the reduction of the drilling e±ciency.In recent years,the drill pipe joint was extensively studied,mainly focusing on the2D axisymmetric model,with a few on the3D mechanical model,but without consideration of the influence of the angle of thread and the bending of the hole at the same time.The ultimate bearing capacity of the drill pipe joint was not well studied.In this paper,a3D numerical simulation model of the drill pipe joint and a model to convert the borehole curvature to the loading moment are established based on the principle of the virtual work,the von Mises yield criterion and the nonlinear contact theory,taking account of the in°uence of the angle of thread and the bending of the hole at the same time.The make-up property of the drill pipe joint is studied,as well as the in°uences of the borehole curvature on the connection strength and the sealing property of the drill pipe joint,and the ultimate working pull and the ultimate working torque of the drill pipe joint are calculated with consideration of the preload,the bending load and the dynamic load safety factor.It is shown that the make-up torque can provide a certain initial contact pressure to ensure the connection strength and the sealing property of the drill pipe joint in the process of the downhole operation.The borehole curvature has a great influence on the connection strength and the sealing property of the drill pipe joint in the process of the downhole operation.The connection strength and the sealing property of the drill pipe joint will be much aected under some common operating conditions.In consideration o