Numerical Calculation Of Unsteady Flow Of Viscoelastic Fluid In The Eccentric Annulus

At present, the technique of polymer-flooding has been widely used in oil field becauseof its high oil recovery. Seen from the application on field, eccentric wear ofpolymer-flooding well is indeed much more serious than that of other wells. Meanwhile,polymer-flooding well also gets other problems, such as broken rod rates increases and theperiod of examining pumps shortens. This increases the cost of oil recovery greatly.Preliminary theoretical analysis and experiments both show that the viscosity and elasticity ofpolymer solution makes the sucker rods get a radial force vertical to its axes when the suckerrods of polymer flooding well does periodical in-and-fro motion in the eccentric annulus, andthe radial force makes the sucker rods lose stability earlier when it was pressed down stroke,and aggravate eccentric wear of the sucker rods of polymer flooding well. Therefore,numerical calculating on flow field of polymer-flooding produced fluid in the wellbore andproposing corrective measures on the basis of the analysis of force on sucker rod not onlyhave the theoretical value, but also get a large engineering significance.This article uses the GAMBIT software to build a dynamic physical model of wellboreannulus and optimized the computational grid. Use POLYFLOW software, using lowerOldroyd-Maxwell model to achieve the dynamic numerical simulation on flow field ofviscoelastic produced fluid in eccentric annulus. Obtained the velocity distribution and stressdistribution; detailed analyzed the influence of eccentricity, sucker rod motion parameters andof the fluid viscoelastic properties on velocity field, stress field and radial force. Results showthat eccentricity and fluid elasticity is the fundamental cause of the radial force and intensifiedeccentric wear. Given several specific technical measures to reduce eccentric wear andestablished a software of optimizing centralizer spacing.