水平井段管柱屈曲与摩阻分析

利用有限差分法和Newton迭代法 ,计算了斜直井段管柱螺旋屈曲临界力、沿螺旋段分布的管柱与井壁接触力以及后屈曲平均侧向接触力。分析了钻杆接头对水平井段钻柱屈曲临界力和弯曲应力的影响 ,提出了计算钻柱正弦屈曲临界力的新方法。结果表明 ,当轴向压力较小时 ,钻杆接头引起钻柱弯曲应力 ;当轴向压力较大时 ,接头会抑制螺旋屈曲的发生 ,降低钻柱的弯曲应力。另外 ,给出了水平井段钻柱出现反转的判别式。

Effects of Turular Buckling on Torque and Drag in Horizontal Well

The critical load of the pipe helical buckling, contact force distribution of pipe on the bore hole and the average side contact force of the pipe post buckling in the horizontal section of horizontal well are calculated by using the finite difference method and the Newton iteration method. The effects of the connectors on the critical buckling load and the bending stress of pipes in horizontal section are analyzed. The results of calculation show that the connector can cause the bending stress of drill pipes when axial forcer is small, and it can restrain the helical buckling behavior and reduce the bending stress of drill pipes when the axial force is large. Thus, a new calculating method is given for the sinusoidal buckling load in horizontal section of drill pipes with connectors. In additin, a criterion is deduced theoretically for predicting the backward whirling of pipes in horizontal section.