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本文用三维直梁单元将下部钻具组合离散化,建立了数值分析模型来模拟下部钻具组合在钻井过程中的瞬时动态特性。考虑了钻压、转速、摩擦及井眼弯曲等对钻具组合的影响,建立了动力微分方程,采用威尔逊-θ法求解。把钻柱与井壁的接触视为瞬时碰撞,采用一种新的方法确定碰撞时刻,对动态分析的结果作了全面的讨论,用井斜力和方位力的时间平均值来预测钻头的走向,并与静态分析的结果作了比较,吻合较好。本文所提供的动态分析方法和计算机程序可供定向井钻井部门参考使用。
In this paper, the three-dimensional straight beam element is used to discretize the bottom hole assembly. A numerical analysis model is established to simulate the transient dynamic characteristics of the bottom hole assembly during drilling. Considering the influence of the bit weight, rotation speed, friction and borehole bending on the drilling tool assembly, dynamic differential equations were established and solved by Wilson-θ method. The contact between the drill string and the shaft wall is regarded as an instantaneous collision. A new method is used to determine the timing of the collision. The results of the dynamic analysis are comprehensively discussed. The time-averaged value of well inclination and azimuth force is used to predict the direction of the drill bit , And compared with the static analysis results, good agreement. The dynamic analysis methods and computer programs provided in this paper are available to the directional well drilling department for reference.