钻柱瞬态动力学失效分析

目前钻柱瞬态动力学的研究大部分处于理论阶段,计算工作量大,而且针对钻柱的动态失效分析还比较少。为此,考虑钻柱轴向力的作用,在一定条件下发生屈曲,诱发横向振动,使钻柱的一些部位与井壁碰撞,建立钻柱的动力学模型;通过ANSYS软件,用Newmark方法,分析钻柱承受任意随时间变化的钻压的动力响应,提取钻柱上的危险点。实例计算和分析结果表明,钻柱的实际断点一般都接近危险点,且断点处交变应力的变化幅度比较大,从而为钻柱的失效和断裂提供了理论依据。

Analysis on drill string transient dynamic failure

At present, drill string transient dynamic researches, which have lot of calculations, less consideration of dynamic failure analysis on drill string, are mostly for theoretical study. Therefore it is considered that inflexion is caused on its axial force under certain conditions, and lateral vibration is induced, by which colliding on parts of the drill string with well bore is induced, thus a dynamic model is established for the drill string. The dynamic response of pressure imposed on the drill string, which is changed with time, is analyzed by using Newmark with ANSYS, and dangerous points on the drill string are determined. The results of example calculation and analysis indicate that the breaking points of drill string close to the danger points, and range of alternate stress at the breaking points change greatly, thus a theoretical basis is provided for analyzing drill string failure and breaking.