地面驱动螺杆泵井杆管环空螺旋流数值模拟

Numerical simulation of helical annular flow between pumping rod and tubing in surface-driven progressing cavity pump well

目前多数研究将地面驱动螺杆泵井杆管环空中的井液的流动看作多相流体轴向流动,实际上在高速旋转抽油杆带动及螺杆泵压差作用下,环空液体呈现螺旋流动。根据粘性流体运动方程及螺杆泵井井筒液体运动的特点,建立了地面驱动螺杆泵井幂律流体杆管同心环空螺旋流数学模型。运用不均匀对数网格法和有限差分法求其数值解,并对不同的流场参数进行了敏感性分析。计算结果表明,井液的轴向速度、切向速度、合速度及压力梯度随抽油杆转速的增加而增加,视粘度随转速的增加而减少。在设计螺杆泵井转速时,既要考虑增大产量,又要考虑螺杆泵举升高度及寿命。

The liquid in the annulus between the pumping rod and tubing in the surface-driven progressing cavity pump （PCP） well presents the helical flow under the action of rapidly rotating pumping rod and PCP pressure difference. According to the motion equation of viscous fluid and characteristics of liquid movement in PCP wellbore, a mathematical model of helical annular flow between pumping rod and tubing with power law fluids in surface-driven PCP well was established. The numerical solution was obtained with the uneven logarithm grid method and the finite difference method. The sensitivity of different flow field parameters was analyzed. The calculation results showed that the axial velocity, tangential velocity, resultant velocity and pressure gradient increased with the increment of the rotation speed of pumping rod, while apparent viscosity reduced with it. In the design of PCP rotation speed, not only the production increment but also the lifting height and working life of PCP should be taken into account.