涡动钻柱内赫巴流体的流动特性研究

Behavior of Herschel-Bulkely Fluid Flow in Whirl Drill String

为了揭示钻井液在钻柱内的流动特性,采用数值模拟方法建立了涡动钻柱内赫巴流体的流动模型,结合流体力学相关理论,对比分析了速度剖面与表观黏度剖面,研究了钻柱自转速度、公转速度、轴向流速及流体密度等参数的变化对钻柱内流场的影响,得到了各参数对涡动钻柱内摩阻压耗的影响规律。研究表明,公转速度正向增大或反向减小时摩阻压耗都有减小的趋势,自转速度增大时摩阻压耗有增大的趋势。由此可见,考虑钻柱涡动的摩阻压耗变化规律,可使涡动钻柱内钻井液的描述更接近于实际钻井工况,有助于钻井液循环系统的优化。

In order to reveal flow behavior of drilling fluid in drill string, numerical simulation method is adopted to establish a mathematical flow model about Herschel-Bulkely fluid in whirl drill string. Combined with the theory of fluid mechanics, the model was used to analyze and compare velocity and apparent viscosity profiles. The effects of variation in drill string rotation velocity, revolution velocity,axial flow velocity and fluid density on flow field were examined, the regularity of effect with each parameter on friction pressure loss in whirl drill string was found. The study shows that friction pressure loss was reduced with the positive increase or reverse decrease of revolution speed, but friction pressure loss increased with the increase of rotation speed. Therefore,when taking friction pressure loss into account, the description of drilling fluid flow in whirl drill string will be much closer to actual drilling condition, facilitating the optimization of drilling circulation system, it can be of great significance to safe and efficient drilling.