Study On The Structure And Performance Of A New Split Gas-lift Plunger

At present,plunger gas lift technology is the most economical and effective drainage gas production technology which can solve the problem of well fluid accumulation caused by gas field exploitation.In order to improve the efficiency,the separate plunger gas lift technology is introduced to realize the production without shut in.However,at present,this technology faces many problems,such as gas slippage and liquid leakage leading to poor sealing effect,serious leakage,the combination in advance of well running,the difficulty in well running and no shut in at all.According to the principle of split plunger gas lift and the law of liquid discharge operation,aiming at the above problems,based on the typical split plunger structure,this paper carried out the optimization design and numerical simulation research of the split plunger gas lift device.In order to ensure the feasibility of the device design and the effectiveness of drainage and gas production,the research combines theoretical analysis,numerical simulation and indoor experiment.In view of the current problems of gas channeling and liquid leakage existing in the split plunger,the efficiency of liquid discharge is affected,in this paper,based on the structure of the seal ring groove on the outer wall of the typical split type plunger,the structural optimization design is carried out from the aspects of different groove types,groove depth,groove width,groove spacing and groove number,and the numerical simulation research is carried out by using FLUENT software.The results show that the opening of the ring groove on the outer wall of the plunger can form the turbulent sealing effect,obviously increase the pressure difference between the upper and lower sides of the plunger,and improve its sealing performance.Different shape of ring groove has significant influence on the sealing performance of plunger drainage gas production,and the sealing effect of inclined trapezoid groove is the best.When the groove depth is 6mm,the groove width is 12 mm,the groove spacing is 4mm,and the number of grooves reaches 17,the sealing effect of the plunger is the best.In view of the difficulties in running the plunger into the well and the problems in advance combination.In this paper,the optimization design and numerical simulation of the inner hole and seal structure of the plunger are carried out.The results show that the introduction of Venturi inner hole structure improves the ability of the plunger to run in the well,increases the downhole speed by about 41%,and compensates the increased resistance of the plunger to run in the well due to the improvement of the sealing performance.In addition,the ball diameter of the matched ball seal body is correspondingly reduced,the downhole ability is obviously improved,the combination with the plunger in advance is avoided,and there is no falling problem under the atmospheric volume.On the basis of the above optimization results,the numerical model verification experiment,the plunger sealing performance and the liquid discharge experiment were carried out.The results show that the designed split plunger has good drainage performance and can meet the requirements of different well conditions.The leakage under the experimentalconditions is less than 1%.The sealing performance and liquid carrying capacity are improved significantly,and the error between experimental results and simulation results is less than 10%,which further verifies the rationality of structural design and the reliability of numerical simulation.It realizes the continuous and efficient drainage gas production without shut in and has great application value.