The Design And Structure Optimization Of Reverse Circulation Flushing Device Working In The Bottom Hole Of Workover Well

With the development of oil and gas field,in the influence of casing damage and underground geology,the leakage of some oil and water wells is serious which has brought great difficulties to the collect and salvage of debris on the top of the litter.The method of chemical temporary plugging contains the weakness of high operating cost,long operating cycle and especially for the hard damage wells,this method can be hardly worked and lead to the results of well workover failure and scrap.According to this circumstance,the oil field device a new local reverse circulation fisher which can collect and salvage debris without chemical temporary plugging,However in the practical application,the new device has the problems of reverse circulation ability insufficiency and the clastic take rate is low.To solve the above problems,using Fluent software conduct the numerical simulation studying of solid-liquid two phase flow field in the bottom of the hole when the device washing the well,the results show that after changing the direction twice when the flushing medium flowing through the drainage holes,the pressure,velocity and turbulent kinetic energy of the flushing medium dissipation is big which leads to the problem above,eventually generate debris "dead zone" in the bottom of the hole.According to the results above,based on the artificial induced mechanism design whirlwind tornado reverse circulation flushing device,using Fluent software conduct the numerical simulation studying of gas-solid two phase flow field in the bottom of the hole when the device washing the well,the results show that before the improvement of the device structure,the suction ability of the device for the debris near the center of the bottom is good,but for the debris in the zone of the periphery at the bottom and the annular is bad,after adding the outside nozzles,the problem can be solved and the debris can be washed out completely.Using the method of numerical simulation,optimizing two primary structural parameters which are nozzle diameter d and nozzle angle ?,the results show that with the increase of nozzle angle ?,the mass of the gas flow into the device is monotone decreasing and the decreasing in the earlier stage is more;with the increase of nozzle diameter d,the mass of the gas flow into the device turns to be a parabolic trend overall,the mass flow is the largest when d=4mm and the ability of the reverse circulation is the strongest.