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定向井眼的弯曲形态,极大地影响了钻柱的受力状况,井眼轨迹控制特别要求对钻柱的最底端,即下部钻具组合进行深入的受力与变形分析。本文将有限单元法应用于下部钻具组合的三维静力分析。由于对处理方法做了一些改进,使有限单元法更适用于弯曲井眼中的钻柱受力与变形分析。针对钻柱与井壁的接触间题,文中提出了一种新的计算方法,大大缩短了这类问题的计算时间。对一些下部钻具组合进行了分析并论述了钻压、井斜角、井眼扩大、井眼三维曲率和钻头扭矩对钻头侧向力的影响。
The bent shape of the directional wellbore greatly affects the stress condition of the drill string. The well trajectory control particularly requires in-depth stress and deformation analysis of the bottom of the drill string, ie, the bottom hole assembly. In this paper, the finite element method is applied to the 3D static analysis of the bottom hole assembly. Due to the improvement of the processing method, the finite element method is more suitable for the stress and deformation analysis of the drill string in curved boreholes. Aiming at the problem of contact between drill string and shaft wall, a new calculation method is proposed in this paper, which greatly shortens the calculation time of such problems. Some combinations of lower drilling tools were analyzed and the effects of bit weighting, deviation angle, borehole enlargement, borehole 3D curvature and bit torque on bit lateral forces were discussed.