| At present,with the development of China's oilfields entering the middle and late stage,in order to maintain a sustained and stable crude oil production,the tertiary oil recovery technology has been vigorously developed.With the popularization and application of polymer flooding and ASP flooding in oil field,the problem of tubing scaling is serious.The composition and properties of scaling corrosion on tubing driven by polymer flooding and ASP flooding have changed significantly.The scaling composition of oil well has gone through three stages: mainly carbonate scaling,co-existence of carbonate scaling and silicon scaling,and mainly silicon scaling,Even the damage of the tubing matrix and the cost increase significantly,and the cleaning in the afterfield will greatly increase the cost of oil recovery.It is urgent to put forward an efficient,low-cost,green and environment-friendly way to clean the tubing in the well site.Cavitation water jet cleaning technology has the advantages of energy saving and environmental protection.This paper uses this method to clean the inner wall of oil pipe.It is the combination of cavitation phenomenon and water jet technology,using the high temperature and high pressure shock wave and micro jet produced by cavitation bubble collapse to enhance the jet striking effect.It has good cleaning effect and low cost,and is widely used in the industrial cleaning of petroleum,chemical industry,environmental protection and other fields.However,there are few studies on the cleaning of ternary scale in tubing and the prediction of its erosion wear life.Based on RNG k-e turbulence model,mixture model and ZGB cavitation model,the flow field of cavitating nozzle was numerically simulated.The effects of different diffusion angle and length on cavitation were studied,and the optimal structure parameters of cavitating nozzle were determined.Through the numerical simulation method,the flow field of cavitation nozzle with different target distance and injection angle is studied,and the distribution law of pressure field,velocity field and gas volume fraction is obtained.Combined with the tubing cleaning experiment,the optimal target distance and injection angle for tubing cleaning are obtained.According to the optimal spray angle and target distance of cavitation nozzle,the structure of rotating self-propelled cavitation nozzle is designed.The flow field is analyzed by numerical simulation.The distribution of velocity field and pressure field,torque,self-propelled force and jet strike force of rotating self-propelled nozzle under different pressure conditions are obtained.The experiment of self propulsion force of cavitation nozzle was carried out,and the self propulsion force of rotating self propulsion cavitation nozzle under different pressure conditions was measured,which was consistent with the simulation results,and verified the accuracy of numerical simulation.The indoor tubing cleaning experiment and well site cleaning experiment are carried out.The metal primary color can be seen on the inner wall of the cleaned tubing,which realizes the effective cleaning of ternary scaling tubing.Based on the discrete phase model and erosion wear model,the erosion wear of cavitating nozzle is simulated,and the results show that the erosion wear mainly occurs in the tail of the inlet cavity,the tail of the resonant cavity,the front of the cylindrical section and the diffusion section.When the pressure reaches 20 MPa,the cavitation nozzle can be used for 56.8 hours.In this study,the structure of rotary self feeding cavitating jet oil pipe cleaning nozzle is designed,and its flow characteristics and erosion wear law are analyzed.The effective cleaning of ternary scaling oil pipe is realized,which can provide technical support for improving oil pipe cleaning technology and reducing cost. |
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