Study On The Stabilization Mechanism And Treatment Method Of The Effluent Produced By Polymer/Surfactant Binary Flooding

With the development of most oilfields in China has entered the stage of tertiary oil recovery,chemical flooding technology has been widely used in oilfield,such as polymer flooding,binary flooding,ternary flooding and so on.Although chemical flooding technology can improve oil recovery efficiency,it produces a large number of produced water,which is difficult to treat.The components of produced water are complex,including various inorganic salts,suspended solids,crude oil,microorganisms,etc.There are residual oil displacement agents such as polymer and surfactant in the produced water of binary flooding.The interaction between oil displacement agent and raw water greatly enhances the stability of pollutants in the produced water of binary flooding,which makes it more difficult to treat than conventional producted water.In order to make good use of water resources and protect the local ecological environment,it is necessary to develop new and efficient water treatment technology.In the first part of this project,the stability mechanism of produced water from binary flooding is studied.The results of water quality analysis show that the salt content of binary flooding water is high,and it contains polymer and surfactant,which leads to the viscosity,turbidity and absolute value of zeta potential of binary flooding water is higher than conventional produced water,and the stability of particles in water is greatly enhanced.The effects of suspended solids,polymers and surfactants on the stability of binary flooding water were studied by simulating binary flooding water.The results show that suspended solids increase the turbidity and zeta potential of water,decrease the viscosity of water,and have little effect on the average particle size of water;The polymer increases the viscosity and turbidity of water,and decreases the zeta potential of water.The average particle size increases first and then decreases;Surfactant increases the viscosity and turbidity of water,reduces the zeta potential and average particle size of water;The synergetic increase of polymer/surfactant increases the viscosity and turbidity of water,decreases zeta potential,and the average particle size increases first and then decreases.In the second part of this project,the water treatment technology of produced water from binary flooding is studied.Different methods such as gravity sedimentation,filtration,aeration,biological contact oxidation are used to treat binary flooding water.Gravity sedimentation has little effect on the viscosity and zeta potential of water,turbidity removal rate increases with the extension of sedimentation time,and particle size decreases with the extension of sedimentation time.Filtration can reduce the turbidity and particle size of water,and increase the zeta potential.In all filter material,the treatment effect of fiber ball is the best.Aeration has little effect on the viscosity of water,but it can effectively reduce the turbidity and particle size of water,increase the zeta potential of water.Increase the aeration time and gas water ratio can improve the effect of aeration.Biological contact oxidation has little effect on the viscosity of binary flooding water.The effluent viscosity is stable at 1 m Pa·s ～ 1.1m Pa·s.After biological contact oxidation treatment,the turbidity and average particle size of water decrease,and zeta potential increases.Based on the experimental results,an efficient treatment process of produced water from binary flooding is proposed,which is gravity sedimentation → aeration→ biological contact oxidation → filtration.