Research On Performance Evaluation And Optimal Design Of All Metal Progressing Cavity Pump

All metal progressing cavity pump is developed on the basis of the traditional progressing cavity pump(PCP),which can overcome some limitations of the traditional PCP.In recent years,all metal PCP has been successively tested in domestic and overseas oil fields.However,as the invention of all metal PCP is relatively late,the relevant theoretical research lags behind the field applications.It restricts the further promotion of all metal PCP lifting technology to some extent.Therefore,based on the structural characteristics of all metal PCP,the working performance of all metal PCP is intensively studied,and the optimal design of the artificial lifting in the oil well using all metal PCP is carried out in this paper.It can provide an important guidance for the applications of all metal PCP in oil fields.Firstly,a fitting parameter is introduced to conduct a systematic study on the PCPs in different fit modes.Based on different fitting structures,a comprehensive method considering different fit modes is proposed to calculate the theoretical displacement of PCP.The displacement characteristics of PCPs in different fit modes are analyzed in consideration of the chamber sealing cases.At the same time,the influence of the fit degree between the stator and rotor on the PCP displacement capacity is also studied.Based on these,the feasibility and development potential of all metal PCP in clearance fit is analyzed in the application of oil well production.Secondly,combined with the structural characteristics of the clearance fit between the stator and rotor,the slippage channels between cavities inside all metal PCP are analyzed.According to the line contact lubrication theory,the slippage structure parameters are quantitatively calculated,and two clearance slippage models for all metal PCP are established on the basis of slit flow principle.Among them,one is for the laminar slippage comprehensively influenced by pressure difference and shear action,and the other is for the slippage considering different flow patterns.Based on the models,the influences of different parameters on the clearance slippage are studied,and some slippage problems are discussed that should be considered during the normal working of all metal PCP.Thirdly,the working performance including displacement,load and efficiency of all metal PCP is studied through laboratory experiments,and the corresponding energy loss is evaluated and analyzed.At the same time,the mathematical model of load characteristics considering pump internal friction is established on the basis of load experiment results,while the mathematical model of displacement characteristics considering different influencing factors is built based on the slippage model.Accordingly,the comprehensive analysis of all metal PCP working performance is conducted,and some feasible methods are proposed to guarantee its performance.Finally,the mechanical model of rod string is established for all metal PCP production wells,on the basis of which the strength calculation and the design method of rod string are proposed.By combining with the rod string mechanics analysis,the calculation model for the lifting system efficiency is established.Based on these,the optimal design of all metal PCP lifting system is conducted,and corresponding software modules are compiled.The research in this paper not only benefits well understanding of the new lifting equipment of all metal PCP,but also provides a theoretical basis for further research and future development of all metal PCP lifting technology.