关键词: 螺杆泵井, 杆管环空, 幂律流体, 螺旋流动, 有限差分法, 数值模拟

Abstract: 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.

Key words: progressing cavity pump well, annulus between pumping rod and tubing, power law fluids, helical flow, finite difference method, numerical simulation