关键词: 聚合物驱, 机械采油, 黏弹性流体, 抽油杆, 侧向力, 偏心环空, 偏磨

Abstract:

In order to analyze the influence of visco-elastic effect of polymer solution in produced fluid on the eccentric wear of sucker rod in polymer flooding wells, a mathematical formula of the lateral force acting on the surface of sucker rod was derived by analyzing the stress state of fluid. Taking Maxwell model as the constitutive equation for produced fluid containing polymer, the mathematical models for the produced fluid flowing in eccentric annular were set up. The velocity field was obtained by using the numerical method. The lateral force was calculated on the basis of the velocity field. The analysis results showed that the lateral force was caused by the eccentric of the rod in annular and the elasticity of the fluid. Lateral force changed periodically with the reciprocating movement of the sucker rod and lagged behind the rod for about one quarter cycle. There are lateral forces along the rod equably acting on the rods during the upstroke and the down stroke. The lateral force can exceed the minimum load easily and result in the distortion of the rods and the eccentric wear between the rods and tubes. The eccentric wear of sucker rod in polymer flooding wells was more serious than that in water flooding wells.

Key words: polymer flooding, mechanical oil recovery, visco-elastic fluid, sucker rod, lateral force, eccentric annular, eccentric wear