Abstract: With the wide applications of window sidetracking drilling technology in the slim holes, the failure problems of the drilling joints caused by the downhole bending section became increasingly prominent. In order to solve the failure problems of the drilling joints induced by deformation caused by bending load, a three-dimensional finite element model of the drilling tool joints was established based on the theory of elastic-plastic mechanics and experimental results of constitutive model of central pipes, and the connection strength and sealing performance of the drilling tool joints under the bending loads were studied and verified the reliability of the finite element analysis results by the tool joint expansion tests. Then, the key structural parameters were optimized using the orthogonal optimization method, obtaining the optimal parameter combination of the tool joints, and calculating the mechanics properties of API drilling joints and high bending joints. The results show that the optimized connecting thread in tensile / pressure, torque and bending performance is superior to the API thread, which may better satisfy the requirements of slim hole sidetracking drilling.

Key words: slim hole, window sidetracking drilling, drillingtool joint, bending performance, orthogonal optimization, bearing performance

摘要： 随着小井眼开窗侧钻技术的广泛应用，由井下弯曲段引起的钻具接头失效问题日益突出。为解决因弯曲载荷造成钻具接头变形失效的问题，根据弹塑性力学理论及中心管材料本构模型试验研究结果，建立了钻具接头螺纹连接的三维有限元模型，研究了弯曲载荷作用下钻具接头连接强度和密封性能，并通过胀扣试验验证了有限元分析结果的可靠性。在此基础上利用正交优化方法，对其关键结构参数进行优化，获得了钻具接头较优参数组合，对比计算了API钻具接头与高抗弯钻具接头力学性能。结果表明，优化后的连接螺纹在抗拉/压、扭矩及弯曲方面性能均优于API螺纹，能更好地满足小井眼开窗侧钻的钻井要求。

关键词: 小井眼, 开窗侧钻, 钻具接头, 抗弯性能, 正交优化, 承载性能