Study On Discrete Phase Transport Law And Separation Characteristics Of Hydrocyclone

After the oilfield entered the high water cut stage,the formation cementation became worse after long-term water injection development.At the same time,the application of new technologies such as sand filling fracturing,polymer flooding and ASP flooding enhanced the sand carrying capacity of liquid production,and the sand production of some oil wells became more and more serious.As a result,sand carrying phenomenon is inevitable in the process of surface oil-water separation.In the surface oil-water separation method,the hydrocyclone has the advantages of small,high efficiency,rapid and stable,and is widely used in oilfield sewage treatment and produced liquid pre-separation.However,in the process of using the liquid-liquid separation hydrocyclone,if there is the phenomenon of carrying sand in the medium,it will affect the flow field characteristics and separation performance of the hydrocyclone,and then affect the separation accuracy of oil and water.Studying the flow law of oil-water sand threephase flow in the hydrocyclone,mastering the flow mechanism of each discrete phase under the action of three-phase flow in the hydrocyclone,and mastering the influence of sand content on the three-phase separation will reveal the separation mechanism of the three-phase hydrocyclone.Furthermore,it is of certain significance to guide the design of a new and efficient swirl structure.In this paper,taking the axial inverted cone hydrocyclone as the reseachr object,the distribution law of oil-water sand three-phase flow in the hydrocyclone is analyzed systematically.The effects of solid particles on the flow characteristics and separation performance of oil phase and water phase in the swirl field were studied by Euler-Euler method,and the effects of different sand content on the flow field characteristics and separation performance of the hydrocyclone were obtained.The velocity distribution of continuous phase flow field in hydrocyclone is measured by PIV technique.The migration trajectory and motion characteristics of discrete sand phase and discrete phase oil droplets in continuous phase flow field are numerically simulated based on Euler-Lagrange method.The motion characteristics of discrete phase such as trajectory,velocity change and residence time under the action of three-phase flow in hydrocyclone are numerically simulated and analyzed by using DPM model,and the position information,migration time and velocity are coupled.The dynamic characteristics of discrete phase oil droplets,discrete sand phase and oil phase particles in hydrocyclone are described,and the multiple factors affecting the motion characteristics of discrete phase are analyzed and studied.The response surface optimization method is used to explore the influence of the structural parameters of the spiral inverted cone hydrocyclone on the flow characteristics and distribution characteristics of the three-phase flow in the hydrocyclone.The mass efficiency of oil-water separation in the three-phase flow field in the hydrocyclone is taken as the output index.The structural parameters are the input index,the significant relationship between the structural parameters and the separation efficiency of the hydrocyclone is obtained,and the second-order response model of the structural parameters to the separation efficiency of the hydrocyclone is constructed.A new type of hydrocyclone structure suitable for oil-water two-phase medium separation under sand condition is obtained.Based on the Euler-Euler method,the influence of operating parameters on the flow characteristics of oil-water sand three-phase flow field in hydrocyclone is analyzed,and the interaction between oil-water sand three-phase medium in hydrocyclone is calculated.The RSM mixed turbulence model is used to close the time-averaged two-phase flow continuity equation and momentum equation,and the high precision discretization scheme is used to realize the numerical simulation of the flow characteristics of three-phase flow in the hydrocyclone.By means of numerical simulation and laboratory test,the effects of operating parameters and physical parameters on the flow field and separation characteristics of threephase medium in hydrocyclone are studied and analyzed.The influence of multi-parameters on the medium distribution in the three-phase rotating flow field is obtained.