The Study On Injection Booster Tool Optimization At Wellhead Of Shale Gas Well

In this paper,the method of installing ejection tools at wellhead is used to solve the problem of low production of Fuling shale gas well.Firstly,the working principle and development status of the ejector are investigated,and the existing problems of the ejector are pointed out,that is,the fluid properties and working conditions have a great influence on the ejector.The change of influencing factors will lead to a sharp reduction of ejection efficiency.Therefore,the design method and structure of the ejector need to be optimized to improve the ejection efficiency of the ejector.Then,according to the investigation and field experience,an injection tool suitable for Fuling shale gas well is preliminarily designed.A three-dimensional physical model of the ejector is established by ANSYS.The pore throat distance,throat length,throat diameter and diffuser outlet diameter are changed on the basis of the existing structure size through orthogonal test.The simulation results are recorded and calculated by Fluent software.The ejection ratio is analyzed and the optimum size is obtained.The experimental results show that the ejection ratio of the optimum size ejector is increased by 20% compared with the original design.By observing the pressure and velocity of the transverse section of the ejector,the influence of the distance between the holes and throats,the length of the throat,the diameter of the throat and the diameter of the outlet of the diffuser on the ejection efficiency is obtained.Then the back edge of the nozzle is slotted to study the influence of the back edge slotted nozzle on the ejection efficiency.Different slot parameters are set up by orthogonal test,and the simulation results are recorded by using Fluent software.The optimum slot parameters are obtained by calculating the ejection ratio.The results show that the ejection ratio of the nozzle ejector with the optimum slot parameters is 10% higher than that before the slotting.Then the influence of slot number,slot length and slot width on the ejection efficiency of the ejector is analyzed by observing the flow field of the nozzle outlet cross section.It is found that the proper slot parameters will make the nozzle outlet flow direction vortex,and the flow direction vortex is helpful to the ejection In order to improve the ejection efficiency of the ejector,the greater the intensity of the flow direction vortices and the longer the continuous distance,the higher the ejection efficiency.There are optimum values for the number,length and width of the slots,so that the performance of the ejector can be optimized.Finally,the influence of working conditions on the ejector of the slotted nozzle is analyzed by the method of control variables.The results show that the influence of working conditions on the ejector of the slotted nozzle is similar to that of the non-slotted nozzle.The flow rate increases with the increase of the pressure of the working fluid,and increases with the increase of the pressure of the ejecting fluid.With the increase of the outlet pressure,the flow rate of the working fluid remains basically unchanged,while the flow rate of the ejecting fluid decreases gradually,and the efficiency decreases.