Motion Simulation Of Electric Submersible Screw Pump And Study Of Bush Damage Mechanism

The offshore heavy oil resources of China are abundant.Exploiting heavy oil resources economically and efficiently will not only ease the shortage of conventional crude oil in China,but also have important practical and strategic significance.The electric submersible-motor-driven progressive cavity pump(ESPCP)is the preferred method for the thermal recovery of heavy oil in the sea with its unique advantages.As key components of the progressing cavity pump(PCP),stator bushing will be damaged by the high temperature and pressure environment of downhole and the friction between stators,which will seriously affect the work efficiency and service life of the PCP.Therefore,it is necessary to carry out the research work on the ESPCP's motion analysis and its bushing damage mechanism.In this paper,the double-headed PCP is used as the research model,and the heavy oil thermal recovery is used as the working environment.Damage mechanism of bushing of ESPCP was studied using the research method of theoretical research,experimental research,virtual simulation and numerical simulation,utilizing the related knowledge of kinematics,tribology,material science,thermodynamics and so on.The main research work is as follows:(1)According to the internal structure and working principle of the screw pump,the kinematics model of the double-headed screw pump was established.Based on this,the kinematics simulation model of the screw pump was designed and the kinematics simulation of the screw pump was completed.By analyzing the motion characteristics of the fixed point of the screw rotor surface,the interaction between the screw pump bush and the rotor was analyzed from the perspective of kinematics.The influence of the structural shape parameters on the kinematics is studied,which provides a reference for the structural design and optimal design of the PCP.(2)The existing experimental conditions were used to simulate the heavy oil thermal recovery environment,and the high temperature resistant hydrogenated nitrile butadiene rubber(HNBR)was selected as the lining material.The friction and wear test of rubber in high-temperature sand-laden heavy oil medium was completed on the variables of load,speed and sand content.The friction coefficient and wear amount were used as evaluation indicators to analyze the effect of these factors on rubber wear.The abrasion test model between the screw rotor and the rubber bushing in heavy oil thermal recovery was established.Scanning electron microscopy(SEM)was used to analyze the wear surface of the rubber and the surface damage mechanism of the busing was explored.(3)The uniaxial tensile test of rubber material under high temperature and heavy oil environment was designed and completed,and the influence of ambient temperature on the performance of rubber material was analyzed.Based on test data,fit strain energy function on the selection of two kinds of commonly used PCP bushing constitutive model.Determined the constitutive model constant of HNBR at different temperatures in the through comparison of the model's applicability.(4)The numerical calculation model of the rubber bushing was established.The sealing performance of the conventional bushing and equal-wall bushing in the initial assembly,the deformation law under the uniform pressure,the contact condition under the pressure difference and thermal expansion behavior under heat source were comparatively analyze using the finite element method.The influence of factors such as temperature,pressure,friction coefficient,and interference on the stress and strain of the bushing was analyzed.The research results of this paper provide reference for stator and bushing in the structural design,material selection,performance prediction and research of high-performance stator bushings,and have a high reference value for improving the service life and reliability of domestic ESPCP.