Research Of Structural Optimization And Numerical Simulation To Plunger Gas Lift Device In Horizontal Well

Plunger gas lift is an effective method of drainage and gas recovery.Plunger operation in wellbore can separate gas and liquid to prevent gas channeling and liquid falling,make full use of formation energy,and reduce the lifting burden of surface equipment.However,in the production process of horizontal wells,because of the existence of deviation section in the wellbore of horizontal wells,the mechanism of gas-liquid two-phase flow and the law of liquid-carrying in the process of plunger operation are more complex,and the implementation effect of conventional plunger gas-lift technology in vertical wells is not good,which restricts the stable production in the middle and later stages of horizontal wells development.In order to improve the application effect of plunger in horizontal wells,aiming at the problems of sealing and eccentric wear of plunger in horizontal wells,the structure of plunger is optimized by numerical simulation method,and the rationality of the structure is verified by experiments.Aiming at the sealing problem of plunger in horizontal wells,the performance of turbulent sealing groove on the outer wall of plunger was studied,and the groove shape,groove depth,groove width and groove number were optimized.The results show that the opening of grooves on the outer wall of the plunger can achieve turbulent sealing effect,significantly increase the pressure difference between the upper and lower surfaces of the plunger,enhance the sealing performance of the plunger,and the circular groove has the best turbulent sealing effect.When the depth of the groove is close to 6 mm and the number of grooves is 16,the sealing effect is the best.Aiming at the serious problem of non-neutralization and eccentric wear of plungers in the inclined section of horizontal wells,the structure of spiral grooves and internal tangential holes in the lower part of the plunger which produces rotation effect is optimized.The angle,width and depth of grooves are studied.The results show that the structure of spiral grooves and tangential holes produces torque for plungers.The angle of spiral grooves has a significant influence on the rotational torque of rotating dynamic seal plungers,while the width and number of them.Quantity has little effect on the torque.The optimum parameters are obtained byorthogonal experiment,with helical angle of 30 degrees,width of 6 mm and number of helical grooves of 8.Opening tangential holes can generate pressure that makes the plunger automatically in the center of the tubing,and effectively prevent plunger wear.On the basis of the above optimization results,through physical simulation experiments,the operation law of plunger under different gas volume conditions was obtained,and the resistance coefficient of plunger was calculated,which was in good agreement with the numerical simulation results and proved the reliability of the simulation results.The optimized design of rotary dynamic seal plunger has good drainage performance,and the leakage is less than 5%.