Research And Optimization Of Foam Drainage In Surface Gathering And Transportation Pipeline

Surface gathering and transportation technology is widely used in natural gas industry.In the process of pipeline transportation,the increase of liquid in the pipeline leads to the decrease of pipeline transportation efficiency and corrosion in the pipeline,which has become an important problem affecting the safety,stability and efficiency of pipeline transportation.Foam drainage technology has wide applicability.In this paper,combined with multiphase flow theory and foam drainage theory,the indoor simulation experiment of tilted pipe and undulating pipe was carried out,and OLGA software was used to calculate the liquid holdup of tilted pipe and undulating pipe respectively,which provides a reference for the surface gathering and transportation process design of gas field.This paper carries out the following work and draws the following conclusions:(1)In this paper,relevant researches on pipeline liquid accumulation,foam drainage,gas liquid carrying and multiphase flow simulation at home and abroad were investigated,and the formation mechanism of pipeline liquid accumulation and the existing foam drainage theory were expounded.(2)Based on the gas-liquid two-phase flow experimental device,the liquid carrying comparison experiment was carried out under different foaming agent concentrations in the inclined tube.It was found that the amount of liquid carrying in the gas increased after the addition of foaming agent,and it was concluded that the drainage effect was better when the filling concentration was 0.5%,and the maximum drainage rate was 78%.When the inclination Angle is 4°and the gas volume is 65 m3/h,the pressure drop is small and the drag reduction effect is significant.(3)OLGA software was used for numerical simulation of multiphase flow under experimental conditions and compared with the experiment.The errors of pressure drop and liquid carrying amount were both less than 3%,thus verifying the accuracy of simulation results.On this basis,the influence of multiple factors(inlet gas volume,inlet liquid volume,temperature,pressure,pipe diameter,etc.)on liquid accumulation in inclined pipe was studied.According to the simulation results,the formula of gas-liquid two-phase holdup liquid ratio was established by regression.(4)OLGA software was used to numerically simulate the foam drainage process of undulating pipeline,and the influences of various parameters(inlet gas volume,inlet liquid volume,inclination Angle,temperature,pressure,pipe diameter,etc.)on liquid accumulation were analyzed.It was concluded that the undulating inclination Angle,outlet pressure and pipe diameter had a greater influence on liquid accumulation,and the upper inclined pipe in undulating pipe section was the most prone to liquid accumulation.(5)The indoor foam drainage experiment of undulating tube was carried out to further verify the simulation results.With the increase of air volume,the liquid carrying volume first increased and then decreased,and when the air volume was 20～60 m~3/h,the liquid carrying volume was larger and the liquid drainage effect was better.