Study On Flow Characteristics And Structural Optimization Of Constant Flow Water Injection Blanking Plug

Most domestic oilfields have entered the period of high water cut development.In order to improve the overall recovery of waterflooding oilfields,it is necessary to adopt reasonable water injection technology.Layered water injection in oilfields can achieve long-term high and stable production and improve oilfield development effect.Maintaining reasonable and constant water injection volume in water injection process is an important guarantee for enhancing oil recovery.The purpose of quantitative water injection technology is to automatically adjust the valve spool when the pressure difference changes in the downhole,so as to reduce the flow fluctuation caused by the pressure difference change,so as to keep the flow constant as far as possible.The existing constant flow blanking plug has some problems,such as the theoretical relationship between constant flow parameters and structural parameters is not clear,the constant flow effect is poor under the condition of wear and large pressure difference.In this paper,the constant flow mechanism of the constant flow blanking plug is studied,and the geometric model of the internal fluid of the constant flow blanking plug is established.The internal flow field of the plug is simulated by using k-e model.The numerical simulation of internal flow field in different displacement of plug spool was carried out,and the corresponding relationship between displacement of plug spool and pressure difference under constant flow condition was obtained.The relationship between nozzle size and constant flow rate was studied by combining calculation with numerical simulation,and the relationship between nozzle size of constant flow blanking plug and its constant flow rate and pressure difference was obtained.The numerical simulation of erosion wear was carried out and the wear-prone parts of the plug were obtained.A laboratory test device was designed to test the performance of constant current blanking plug.Limitation experiments were carried out on the valve spool.The results showed that the pressure difference increased gradually with the decrease of the sliding valve opening.When the sliding valve opening was small,the pressure difference increased significantly,resulting in poor constant flow effect.The experimental results are in good agreement with the numerical simulation results,which verifies the correctness of the numerical calculation method.An equivalent area method is proposed.The theoretical calculation models of flow rate,spool position and spring stiffness are established.The spring design methods of different constant flow blanking plugs are given,which can be used in the design of different constant flow blanking plugs.Aiming at the problem of poor constant flow effect when the pressure difference is large,the section shape of outlet hole is optimized,and the optimized structure is numerically calculated.The results show that the flow error of the optimized structure decreases when the pressure difference is high,which has better constant flow effect.The research in this paper can provide theoretical guidance for the study of constant flow mechanism and field application of constant flow blanking plug.