Study On Applicability Of The Vortex Tool For Gas Wells Deliquification

In the later stages of the gas wells production,the liquid loading problem will gradually become more serious as time increases.It is necessary to adopt proper drainage and gas recovery technologies to help gas well to drain liquid,otherwise it will cause dead wells.Recently,the vortex tool installed at the bottom of the well has been introduced to assist gas well production.Compared with the conventional deliquification technologies,the vortex tool has the advantages of simple structure,low cost,no pollution and no change of the pipe string structure.In addition,good field tests results have been achieved in gas fields both at home and abroad.At present,most researches on the mechanism of the vortex tool are to analyze the flow field in the steady.state with CFD fluid simulation software.However,the simulation is just in the case that fluid is in mist flow and the actual fluid flow and flow regime in the wellbore are neglected.As a result,mechanism of the vortex tool is misunderstood and the install location of the vortex tool is unclear.Based on the fluid mechanics and gas-liquid two-phase pipe flow theory,this article studies the distribution of each fluid by fluent software in the vertical pipe when fluid flows through the vortex tool,explain the mechanism and the scope of application of the vortex tool.Moreover,the structural parameters of the vortex tool are optimized,and the installation position in the downhole is finally determined,which provides a theoretical basis for the use of the vortex tool in the gas well field.In order to study the dynamic change process of fluid in slug flow,churn flow and annular flow while passing through the vortex tool in a vertical pipe,the transient simulation method of Fluent is applied to analyze the flow field in each flow regime,the result shows that the vortex tool has the ability to convert the partial static pressure into dynamic pressure and increase the tangential velocity of the fluid.Besides,the vortex tool reduces the fluid holdup ratio and the capacity of carrying liquid of gas increases.Compared to slug flow and annular flow,the vortex tool works in churn flow the most efficiently.With the help of the vortex tool,the critical velocity can be reduced by 27%.According to the range of the structure parameters of vortex tool,the fluent software was used to optimize the helix angle,groove width and groove depth of the vortex tool.The results showed that when the helix angle is 55°,the groove depth is 10mm,and the groove width is 45mm,the fluid has small energy consumption,good gas-liquid separation effect and high deliquification ability after passing through the vortex tool.The liquid film model was selected to diagnose liquid loading of three gas wells which are at a gas field.According to the production data of the wells,the Pipesim software was used to simulate characteristic parameters of fluids which are at different depths in the wellbore.Based on Owen gas-liquid flow regime diagram in a vertical pipe,the flow regime of the wellbore is analyzed.Finally,the applicability of vortex tool of three wells and the installation position of the vortex tool are to determined.