旋转钻柱内赫巴流体流动模型与流场特性研究

Research on Flow Model and Flow Field Property of Herschel-Bulkely Fluid in Rotary Drill String

为了揭示钻井液在旋转钻柱内的流动特性,采用数值模拟方法建立了旋转钻柱内赫巴流体的流动模型。研究了钻柱的旋转速度、轴向流速及密度的变化对钻柱内螺旋流场的影响,并给出了合理的解释。通过分析得出旋转钻柱内赫巴流体的流动由于其表观黏度的单峰分布特性,使得螺旋流场减弱了流体质点在各方向上的随机脉动趋势,并增强了流场旋流的整体趋势。该项研究成果对于钻柱内考虑旋转效应流场钻井液流动的深入研究具有指导意义。

To disclose the flow characteristic of drilling fluid in rotating drill string, the numerical simulation method was adopted to establish the flow model of Herschel-Bulkely fluid in rotating drill string. The effects of string rotation speed, axial flowrate and density change on the spiral flow field within the string were studied and the ra- tional explanation was given. The analysis shows that, due to the unimodal distribution characteristic of the appar- ent viscosity, the flow of Herschel-Bulkely fluid in the string makes the spiral flow field weaken the random fluctua- tion tendency of fluid mass point in all directions and increase the overall tendency of the flow filed cyclone. The re- search findings can serve as a guide to the further research on the drilling fluid flow in drill string in consideration of rotation effect.