Research And Application Of Cavitation Jet Hydraulic Oscillator

In view of the fact that with the increase of production time,the scaling phenomenon will be widespread in the wellbore of the oil well.The scaling on the inner wall of the wellbore will shrink the casing,resulting in the risk of sticking the downhole tool during the operation of the oil well,and the serious scaling of the wellbore will reduce the oil production rate.At present,wellbore descaling technologies include screw drill descaling,high-pressure jet descaling and chemical descaling.These descaling technologies have certain limitations in descaling efficiency and descaling effect.Therefore,it is necessary to design a device that can effectively improve the descaling efficiency of the wellbore to improve the descaling efficiency,reduce the descaling time,increase the effective use time of the oil well and improve the economic benefit.Therefore,this paper designs and optimizes the cavitation jet hydraulic oscillator and uses it with the rotating jet descaling device to improve the descaling efficiency.The cavitation jet hydraulic oscillator couples the hydraulic pulse vibration with the cavitation effect of the jet,that is,on the basis of the hydraulic pulse oscillation,the internal jet of the oscillator further produces the cavitation effect,and the generated jet cavitation effect effectively increases the vibration frequency and amplitude of the oscillator,thereby improving the efficiency of wellbore descaling.The research contents are as follows:(1)Analyze the principle of cavitation and descaling,and study the conditions required for cavitation through mathematical models.The overall structure of the cavitation jet hydraulic oscillator is designed and the main parts are explained.The working principle of the oscillator and the working process of the main part are analyzed.(2)The numerical simulation process of cavitation jet hydraulic oscillator is introduced,and the three-dimensional model and calculation model of the oscillator are established.The grid independence of the internal flow field model is analyzed by using ICEM.The established oscillator model is numerically calculated by Fluent.The advantages of the cavitation model in this paper are obtained by comparing the cavitation cloud diagram of the numerical simulation results with the general submerged jet cavitation cloud diagram.The internal flow field characteristics of the oscillator are obtained by analyzing the velocity cloud and pressure cloud of the numerical simulation results.(3)The orthogonal numerical simulation is designed with the oscillation frequency as the evaluation index.The three key structural parameters of the cavitating jet hydraulic oscillator are the angle of the jet nozzle,the distance from the jet nozzle to the inlet of the cavitation throat and the length of the cavitation throat.The main structural parameters of the cavitating jet hydraulic oscillator are optimized by the response surface method in the Design-Expert 8.0 software,and the optimization results are verified by simulation.The simulation results show that the optimal solution of the parameters obtained by solving the regression model is reliable,indicating that the solution of the regression model is highly consistent with the simulation results.(4)The problem of wellbore scaling in Hua H17-5 well is introduced,and the descaling process is analyzed.The hydraulic oscillator and its supporting equipment are introduced.The test method and construction technology were studied.In the outdoor test,the oscillation amplitude of the optimized hydraulic oscillator is related to the water displacement.The larger the water displacement is,the larger the oscillation amplitude is.The numerical simulation results of the optimized oscillator are close to the experimental results,which verifies the accuracy of the simulation results.The use of the optimized hydraulic oscillator has little effect on the speed of the rotary jet washer.The optimized cavitation jet hydraulic oscillator at high flow rate has greater advantages than the traditional hydraulic oscillator.In the field test,the combination of the optimized cavitation jet hydraulic oscillator and the rotary jet flusher can better and faster clean up the wellbore fouling,improve the operation efficiency,and make the oil well put into production faster.