深水钻井隔水管段大尺寸环空压耗数值模拟

深水钻井过程中海水段隔水管环空中的水力学特性与常规井有较大差别。运用理论分析的方法对海洋深水钻井隔水管段大尺寸环空中的压力损失进行了研究,分析了环空泥浆返速、钻杆旋转速度、钻井液性能和环空尺寸等对压耗的影响,并与常规井眼环空压耗进行了对比。研究结果表明:在大尺寸环空中,对于幂律流体,在层流状态下环空压耗随钻杆转速的增加而减小;随着环空尺寸的增大,环空压耗急剧降低;随钻井液流变指数和稠度系数的增加,环空压耗呈指数增大和线性增大。本文可为研究隔水管环空螺旋流携岩规律提供帮助。

Numerical simulation of pressure loss in large size riser annular in deepwater drilling

Hydraulics in annular of large hole differs greatly with that of a conventional wellbore. A numercial study in deepwater driling on pressure loss in large size annular of riser was conducted in this paper, the effects upon pressure loss from return velocity of drilling fluid in annular, rotation speed of drilling pipe, drilling fluid property were analyzed. The calculation results showed that pressure loss for power-law fluids in large size annular increases with increasing pipe rotation in turbulent flow and decreases with increasing pipe rotation in laminar flow. The pressure loss sharply decreases with the annuli size increasing. Pressure gradient increased exponentially and linearly with the increment of drilling fluid rheological parameters and consistency coefficient. What was researched in this paper can offer some help for cutting-carrying in deepwater drilling riser annular.