柔性钻杆优化设计及承载能力研究

Optimal Design of Flexible Drill Rod and Research on Its Bearing Capacity

根据柔性钻具的工作状态和井眼曲率半径,采用强度理论和几何关系,考虑柔性钻杆与井眼曲率的柔度匹配,使柔性钻杆在安全承载的条件下柔度达到最大,对柔性钻杆主要结构参数进行了优化设计,推导出相应的计算公式。采用数值模拟方法,考虑柔性钻杆各部件间的接触非线性和材料非线性,建立了单节柔性钻杆局部模型,采用增广的拉格朗日接触算法进行计算,得到造斜段柔性钻杆能承受的极限扭矩为2. 0kN·m,为验证数值模拟方法的正确性,对柔性钻杆开展了扭转试验研究,可知柔性钻杆的破坏扭矩与数值模拟得到的结果相吻合。

Considering working conditions of flexible drill rod and wellbore’s radius of curvature,the strength theory and geometrical relationship and the matching of flexibility parameters such as flexible drill rod and borehole curvature,the softness of the flexible drill rod was maximized under safe loading condition.Main structural parameters of flexible drill rod were optimized and the corresponding calculation formula was derived.Through using a numerical simulation method and considering the contact nonlinearity and material nonlinearity of the flexible drill rod’s components,the local model of a single flexible drill rod was established,including adopting the extended Lagrangian contact algorithm for the calculation so as to obtain a 2.0kN·m ultimate torque that the flexible drill rod can withstand at the whipstock section.In order to verify correctness of the numerical simulation method,a torsion test was conducted on the flexible drill rod to show that,the destructive torque obtained by the flexible drill rod agrees well with the results obtained by numerical simulation.