深直井旋转钻柱空转功率消耗的数学建模

A Mathematic Model for the Unloaded Power of Rotary Drill String in Deep Straight Well

摘要:

通过对深井旋转钻柱空转功率消耗因素的分析，考虑空转时离心力作用在井壁上引起的摩擦力导致的功率消耗，并将钻井液视为牛顿液体，运用柱坐标系建立了旋转钻柱在深井作业条件下空转功率消耗的分析模型。综合考虑空转功率与钻柱旋转的角速度、钻柱与井眼结构参数、钻井液粘度系数等因素间的关系，即旋转钻柱运动过程中的离心力和钻井液作用在钻柱上的剪切应力对功率的影响，建立了更加符合实际工况的数学模型。

Abstract:

This paper presents an analytical model at the cylindrical coordinate system for the power consuming of the viscous force caused by centripetal force of the drill string while rotating without weight on bit (WOB). The drilling mud in this model is assumed to be Newton fluid. Therefore, this model has a good accordance with the reality by synthetically considering the rotate angular velocity, the structure parameters of the drill string and the well, the viscous coefficient of drilling mud and etc. That is, the centripetal forces of the drill string and the shearing strength caused by the fluid are considered in the model, which makes it have a better utility than those existing.