Pilot Test Study On Advanced Treatment Of Oil Water From ASP Produced Water

Crude oil continuous and stable production in Daqing Oilfield is very important for the regional economic and social development.However,the exploitation of the crude oil is more and more difficult and the production quantity is decreasing year by year since the 60-years found of the Daqing oilfield.A series of technological and management measures have been adopted to maintain the production quantity,such as deploying infill wells,water flooding in a fine way,polymer flooding and ASP flooding.As for ASP flooding,high polymer concentration,high basicity,high viscosity and serious emulsification in ASP flooding wastewater make oil-water separation and suspended solids removal more difficult.Furthermore,production of thinner and worse oil reservoir requires the water flooding must meet standard of advanced treatment.The existing treatment process of oil field wastewater is increasingly not suitable for the needs of fine water injection and tapping potential to increase oil production.Therefore,it is very imperative for studying of ASP flooding produced water advanced treatment.In this paper,Daqing oilfield production wastewater is taken as the research object,the main factors affecting the water quality performance of oil production wastewater are determined through water quality analysis,and the conventional treatment process and advanced treatment process are used to treatment the wastewater aiming to remove oil pollutants and suspend solids(SS),and reduce viscosity.Based on this,the combination process is determined,and its treatment effect and economic benefit are analyzed,and the best combination process is selected for the treatment of oil production wastewater from ASP flooding in Daqing Oilfield.This study is on the basis of industrial waste water to perform water quality analysis based on the characteristics of Daqing oilfield produced water,to confirm the vital factors of influencing the produced water and two treatment processes have been selected which are ordinary treatment process and advanced treatment process.This thesis analyses the treated water quality treated by the above two processes and develops the experiments on removing of oil,SS and reduction of viscosity.Compared those indexes with the inlet water quality to check the feasibility of the processes.Conventional treatment process can remove more than 90% of the oil in the oil production wastewater and about 50% of the viscosity and SS,which suggests that the selected conventional treatment process section can effectively remove the oil,suspended solids and other impurities in the wastewater,as well as polymer,so as to reduce the viscosity of the wastewater.The removal rate of dissolved air flotation is more than 60%,suggesting that the selected process is feasible for the treatment of ASP flooding wastewater.Biochemical process can effectively remove oil,organic matter,suspended matter,and has a certain viscosity reduction effect suggesting that the process can adapt to the treatment of ASP flooding oil production wastewater.Although the conventional process has a certain treatment effect on oil pollutants,SS and viscosity,it still can not meet the conditions for stable operation of the double membrane system.Therefore,the research on advanced treatment process is also carried out in the paper containing advanced oxidation process(AOP),two-stage filtration and ultrafiltration.The results show that the viscosity of the treated effluent is less than 2 m Pa·s after treatment of AOP.The two-stage filtration is mainly used to remove the SS in the wastewater which make the concentration of SS less than 20 mg/L.Finally,ultrafiltration is used to further remove the suspended solids,and thus the effluent can meet the water quality requirements of reinjection water in the low permeability layer of the oilfield.Based on this,the combination process was developed which is combination process of air floatation oil removal,biodegradation,AOP,two-stage filtration,and ultrafiltration.Analyzing of treatment effect and economic cost,we further affirmed that the combination process can be used to treat the ternary complex flooding and production wastewater.The results show that after treatment by combination process the oil content of the effluent is less than 2 mg/L,the suspended matter is less than 5mg/L and the viscosity is less than 1.5 MPa·s,which can reach the reinjection standard.The process energy consumption is 2.98 kwh/ton and the treatment cost is1.86 yuan/ton.In a word,the combined process is feasible in technology and reasonable in economic cost,and can be used for the treatment of ASP flooding wastewater.