Modeling And Numerical Simulation Of Oilfield Wastewater Treatment System

Water injection is the main way of oilfield development in China,which makes the produced water contain a large number of suspend solid,wasted oil and chemical substances.Oilfield wastewater treatment is to purify the oily wastewater from oil transfer station,dehydration station and combined station by means of sedimentation and filtration,so as to achieve the required water quality index and reinjected into underground for reuse.Obviously,its treatment effect directly affects the exploitation and environmental protection of the oilfield.At present,the classification of reinjection layers is more detailed and the requirements for water quality are more strict.The common problems in the wastewater treatment of oil field include increasing difficulty in prediction of settlement concentration,the size of filter effluent particles not meeting the demand,unreasonable setting of backwash parameters in backwash process,and the effect of backwash is not obvious.The research on the mechanism of oily sewage treatment,the establishment of the global mathematical model and simulation analysis of the sewage will reveal the process and law of sewage treatment,which is of great significance to improve the effect of oilfield wastewater treatment.This paper focuses on the three main process of sewage treatment,sedimentation process,filtration process and backwashing process.The important parameters of the simulation process are obtained through the experimental analysis of the sewage samples.Starting from the economic benefits of sewage treatment,the three main processes of sewage treatment are numerically simulated,and the corresponding mathematical model is established to optimize part of the process.For the research of gravity settling tank,based on Takacs model in urban sewage treatment,the mathematical models of suspended solids settling and oil floating are established.In this model,the overall influence of settling tank structure,inlet water concentration,inlet water flow and other factors on the settling process is comprehensively considered;considering the floating characteristics of oil and the coupling of oil floating and suspended solids sedimentation,an improved mathematical model of oil floating is constructed,so as to obtain the variation law of the effluent concentration of oil and suspended solids with time;and according to the different concentrations of suspended solids The optimal settling time is calculated by the quadratic surface method,and the primary and secondary relationship among flow rate,time and treatment capacity is explored.For the simulation of the filter tank,the network model trajectory tracking method is used to analyze the force and displacement of a single suspended solid particle or oil drop,and the particle trajectory and the distance from the channel center are obtained to judge whether it is adsorbed.Through this model,not only the concentration variation of suspended solids and oil droplets at the outlet,but also the particle size distribution at the outlet can be obtained.The backwashing process is mainly aimed at the filter tank,and the backwashing model including mixing and water flow is established.In this model,the change law of backwash effluent concentration can be obtained,and the best backwash time can be calculated.And through multi factor analysis,the primary and secondary relationship of the treatment capacity,backwashing intensity and backwashing time on the backwashing effect was analyzed.In this paper,through the modeling and numerical simulation of sedimentation,filtration and backwashing,the mechanism of oily wastewater treatment process is studied,and the process and law of wastewater treatment are revealed.At the same time,it will also provide a theoretical basis for improving the efficiency of oilfield sewage treatment and its potential economic benefits,which is of great significance to improve the effect of oilfield sewage treatment and build a green and intelligent oilfield.