Abstract: The contact and friction of drill pipe string with the borehole wall in a directional well is a geometrically non-linear problem.The contact and friction as well as the torsional effect of a drill pipe string is studied in this paper.A three-dimensional quasi-static model of stress analysis of a whole drill pipe string and a spatial multi-directional contact and friction clearance element are established with the finite element method.The contact and friction of a drill pipe string with borehole wall and its deformation are analyzed and calculated with modified Newton iteration and approximate gradient increment of loading.Field tests have proved that the prediction of well trajectory with the proposed theory and model agrees with the after-drill measurement.

摘要： 考虑钻柱的扭转效应和接触摩擦,用有限元法建立了整体钻受力分析的三维准静力学模型和空间多向接触摩擦间隙元.用修正的牛顿迭代法进行迭代运算和用近似梯度增量法修改载荷增量,并对钻柱与井壁的接触摩擦和钻柱变形进行了分析计算.现场实验证明本文提出的理论和模型用于井眼轨迹跟踪预测结果与钻后实测结果符合很好,可作为定向井钻柱受力分析以及井眼轨迹设计和预测的一种基础理论和实用方法.

关键词: 钻柱力学, 有限元法, 三维静力学模型, 接触摩擦间隙元