Numerical Simulation And Structure Optimization Of Downhole Gas-liquid Spiral Separator

With the deepening of gas-field exploration in China,the moisture content in the gas-field has gradually increased.Some gas-fields in our country have entered the stage of high-water-bearing exploitation,which leads to the increasing problem of gas-water separation.At present,the process of drainage and gas recovery in gas well is mostly to extract liquid from wellbore to the ground,to separate the gas and liquid on the ground,and then gather the liquid and pump into the stratum after pump pressure.Although this model can effectively solve the question of gas well effusion,it requires a complicated surface gas-liquid separation and injection system.This not only increases the equipment cost,causes a waste of floor space,but also increases the lift.The mineral salts in the water can also corrode the tubing and related devices.This paper proposes a technique for separating gas and liquid from gas wells using spiral separators.It can direct the separated water back to the formation.As a critical equipment in gas well production,the advantages and disadvantages of downhole gas-liquid spiral separators have a major impact on the exploitation of natural gas.Therefore,it is of great significance to improve the research design level of the downhole gas-liquid spiral separator and improve the separation efficiency and overload capacity of the spiral separator.In this paper,a kind of downhole gas-liquid spiral separator is taken as the research object,and the CFD numerical simulation and structure optimization are carried out.The specific content and related research results are mainly divided into the following aspects.(1)In this paper,a downhole gas-liquid spiral separator is taken as the research object,and computational fluid dynamics software is used to simulate the flow field and the gas-liquid two-phase flow field in the spiral separator.The relationship between the structure parameters of the gas-liquid helix separator and the pressure loss of the spiral separator,the internal flow field and the separation efficiency are studied.According to the numerical simulation results,and the comprehensive production of cost,capacity loss and separation efficiency and many other factors,optimized design of the optimal spiral structure.The screw pitch is equal to 60mm,and the winding number is equal to 2 laps(2)In this paper,an elliptical gas-liquid spiral separator is designed from the viewpoint of optimizing the structure of the spiral separator to increase the turbulence effect and thereby increasing the possibility of colliding and polymerization of droplet particles of the same-sex particles.The CFD technology is used to simulate the separation process of the gas-liquid two phase flow,and the optimum short axis length of the elliptical outer tube is optimized according to the numerical simulation results.The results show that when the length of the short axis of the ellipse is 60mm,the separation efficiency is the best,and the separation efficiency of the droplet particles with the separation particle size of 10?m is ninety percent.(3)Based on ANSYS/CFD software,numerical simulation of downhole gas-liquid separators under different gas-liquid inlet velocities is carried out by using fluid solid coupling numerical analysis method.The relationship between the impact force of the spiral blade and the gas-liquid velocity at the inlet,the relationship between the deformation of the spiral blade and the gas-liquid velocity at the inlet were obtained,and the mathematical function relationship between them was obtained by means of numerical analysis.(4)In view of the problem of insufficient overload capacity of the spiral blade of the gas-liquid spiral separator,a double spiral blade electromagnetic separator is designed to increase the overload capacity of the spiral blade with the change of the gas-liquid flow rate,so as to improve the overload capacity of the downhole gas-liquid spiral separator.This paper introduces its working principle,and uses the numerical simulation of CFD/ANSYS technology to obtain the deformation of the optimized spiral blade.The results show that when the inlet velocity is 30m/s,the maximum deformation is decreased from 2.98mm to 0.018mm compared to the spiral blade before the design,and the deformation is obviously reduced.