斜直井中考虑摩擦时钻柱的正弦屈曲分析

Sinusoidal Buckling Analysis of Drill String with Friction in Deviated Wells

提出了在斜直井中钻柱正弦屈曲分析时对摩擦阻力的处理方法,给出了考虑摩擦阻力时的屈曲平衡方程,建立了相应的微分求积法列式,用微分求积法时平衡方程直接求解。在力学模型中考虑了摩擦因数、重力线密度、钻柱长度和井斜角对临界载荷的影响,并将数值计算结果与实验数据进行了比较。分析表明,提出的在钻柱正弦屈曲分析时对摩擦阻力的处理方法是正确有效的,能够为实验结果提供理论分析基础;在同等条件下,钻柱正弦屈曲临界载荷随摩擦因数的增加而增大;钻柱越长,摩擦阻力对临界载荷的影响越大,在一定程度上,摩擦可以增加钻柱的稳定性。

A method for lateral buckling analysis of tubing with frictional resistance in deviated wells was presented.The equilibrium equation with frictional resistance was derived and solved by u- sing the differential quadrature method.The effects of frictional coefficient,gravity,drill-string length,and well deviation angle on the lateral critical buckling load were considered in the mechanical model.Numerical results are compared with the test values.It shows that the method to deal with the frictional resistance is correct and efficient,and that the critical load increases with the increase of the frictional coefficient if other conditions remain the same.The longer the drill-string length is,the greater the effect of frictional resistance on the critical buckling.Friction is beneficial to the stability of drill string under certain degrees.