Numerical Simulation Of Unsteady Flow Of Power-Law Fluid In The Eccentric Annulus

At present,the main way of oil production of our country is mechanical recovery.For the case of deep oil well,pumping rod is eccentric in oil tube during the oil recovery,especially when the pumping rod moves downwards,the sucking fluid treated as power law fluid flow in the eccentric annuli formed by the oil tube rod.The fluids have strong non-Newtonian properties,and the constitutive equations of the fluid itself are more complex,which brings great inconvenience to the calculation of related parameters.This paper conducts extensive research on the research methods of the common eccentric annular air-flow problems in oil production and understands the current status of studies on the eccentric-ring air-flow problems.At the same time,GAMBIT software is used to establish the dynamic physical model of wellbore annulus space and the optimization of computational grids.The computational fluid dynamics method was used to study the eccentric annular air flow field with inner rod reciprocating motion.The UDF program was compiled according to the movement form and law of the inner tube,and the FLUENT dynamic mesh technology was used to realize the unsteady flow of the power law fluid eccentric annular space.Flow 3D flow field simulation calculation.The velocity distribution and stress distribution of the flow field are obtained.The effects of eccentricity,sucker rod motion parameters and fluidity index on the velocity field and the frictional resistance are analyzed in detail.At the same time,the force analysis was performed on the sucker rod joint to investigate the influence of the joint on the stress of the sucker rod.