Research On Effective Working Distance Of Downhole Vortex Tools And Optimization Of Parameters

After the gas field enters the middle to late stage of development,the production of gas wells decreases and the production of water increases day by day,drainage gas production has become an inevitable choice for stable production and enhanced recovery.As a new technology of drainage and gas production,vortex tools have been widely used abroad and achieved good results.However,the effect of using vortex tools in domestic gas wells is not good.The reason is that people don't have a clear understanding of the condition of using vortex tool,selecting well not appropriate,and the parameters structure needing to be further optimized.Firstly,this paper analyses the liquid carrying model and the pressure drop model of gas-liquid two-phase pipe flow,and optimizing the Li Min model,H-B model and Liu Tong model.The feasibility of the simulation is verified by comparing the experimental results with the simulation results,and the gas-liquid two-phase flow in the vortex tool runner is analyzed.When the gas-liquid passes through the vortex tool,the tangential and axial velocities will change.The action distance between the tangential and axial velocities from the beginning to the disappearance of the tangential velocities and the return of the axial velocities to the normal velocities are relatively short.The results show that the variation of tangential and axial velocities are not the key factor affecting the effective distance of vortex tool.The optimal pressure drop models(H-B model and Liu Tong model)are used to calculate the pressure drop in the wellbore when the vortex tool is not installed or installed,and the actual flow velocity and critical flow velocity are calculated.It is found that the vortex tool reduces the critical flow velocity by 16.1%.It is revealed that the essence of drainage and gas recovery by vortex tools lies in the change of liquid phase flow pattern,which makes the dispersed droplet flow become annular flow.Based on the data of 6 production wells using vortex tools,the critical flow velocity is calculated.The results show that the maximum critical flow velocity can be reduced by 40%.Therefore,when a well without using vortex tool,when the ratio of actual flow velocity and critical flow velocity in the range of 0.6 to 1,the vortex tool can be used to discharge liquid effectively,the effective action distance is 1100-1700m.The effects of pitch,height of blade,inner diameter,multiple of lead and number of blades on the effect of vortex tool are analyzed from the angles of liquid distribution,tangential velocity and axial velocity.Finally,the optimal parameters combination of the vortex tool is analyzed from the angle of orthogonal experiment.When the parameters of the vortex tool are:54 mm inner diameter,200 mm pitch,20 mm blade height,1 time lead and 1 blade,the effect of the vortex tool is the best.