| Compared with the ordinary water flooding technology,the oil recovery rate of ASP(Alkaline/Surfactant/Polymer)flooding technique has increased by 20 percentage points,and play the key role in the stable production and increase production of the oil field.With the popularization and application of ASP(Alkaline/Surfactant/Polymer)flooding technique in domestic oilfields,a large number of waste water has been produced.The water produced by ASP flooding has characteristics such as complicated composition,serious emulsification,high viscosity and difficulty in treatment,and is a difficult problem to be solved for oil field and environmental protection.The demulsification and destabilization of water produced by ASP flooding technique is the precondition for improving the efficiency of oil-water separation.This paper starts from the recognition of characteristics of water produced by ASP flooding.Through laboratory tests and pilot scale tests,the interfacial characteristics and sedimentation characteristics of water produced by ASP flooding are analyzed,suitable demulsifiers are screened and compounded.Finally the pilot test of oil and water separation was conducted with high-efficiency separation device.The main contents are as follows:(1)Analysis of separation characteristics of water produced by ASP flooding.A ternary compound flooding simulation water sample was configured to examine the effects of alkali,polymer,and surfactant content on the interfacial characteristics such as viscosity,Zeta potential,and surface tension of the ternary compound flood water simulation water sample;Subsiding experiments were conducted to investigate the influence of the interaction of oil-displacing agents(alkali,polymer,and surfactant)on the sedimentation of produced water in the effluent system of ASP flooding.The results show that the presence of alkali can decrease the surface tension,increase the Zeta potential and increase the stability of the alkali content.The presence of surfactant can decrease the surface tension,increase the Zeta potential surfactant content and increase the stability of the alkali content.The presence of polymer can decrease the surface tension,increase the Zeta potential surfactant content and increase the stability of the alkali content.The coexistence of alkali,polymer and surfactant can enhance the stability of the system.(2)Filtering and compounding of demulsifiers for the water produced by ASP flooding.Self-made polyether polyquaternium inverse demulsifier(PPA),commercial water-soluble demulsifiers SL-Wz and SL-01,and commercial oil-solubledemulsifiers SL-Le and SL-Wd were used and their effects of demulsification were compared.The effects of a single demulsifier on the viscosity and Zeta potential of the effluent system of ternary flooding were investigated.On this basis,the demulsification effect of the compounded demulsifier and the effect on the viscosity and Zeta potential of water from the ternary compound flooding were investigated through a variety of compounding methods.Finally,the compounding demulsifier PPA + SL-01 was determined to be used for pilot-scale experiment.(3)Column air flotation separation test of water produced by ASP flooding.A pilot-scale oil-water separation study was conducted with a cyclone-static microbubble flotation column.The influence of factors such as cycle ratio,aeration,foam layer thickness,treatment volume and demulsifier dosage on the deoiling rate was investigated.Under the optimized conditions,24 hours continuous running test was conducted,and after the primary air flotation separation,the oil deoiling rate reached 90%.The collision and adhesion process between oil droplets and bubbles was analyzed to establish the deoiling kinetic equatio.The experimental results show that the cyclone-static microbubble flotation column device combines the processes of air flotation,cyclone separation,and coarse granulation,so it has the advantages of large processing volume,low operating cost,and good treatment effect. |
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