Research On The Viscosity Reduction Effect And Oxidation Mechanism Of Ozone Oxidation Method For ASP Produced Water Of Oilfield

With the widely used of the ASP technology for driving oil in Daqing oilfield,the producted water of oilfield is carrying a great deal of oil displacement agent,which make it more difficult for sewage treatment.In this paper,we attempt to reduce the viscosity of ASP producted water by the method of the advanced oxidation.Based on the research,we investigated the influence factors of viscocity during the process of preparing polyacrylamide solution.Further more,we studied the influencing factors of ozone oxidation and degradation mechanism,we also optimized the field operation conditions of oxidation process.By simulating field conditions we made the polyacrylamide solution and investigated the influence of different conditions on the viscosity of solution.It showed that the viscosity of the solution will decrease with the increase of placing time and temperature,and the viscosity will get lower when the shear rate get faster.By investigating the effect of different advanced oxidation methods on the viscosity reduction of produced water,the optimum method was determined.The results showed,comparing with NaClO method and potassium ferrate method,ozone method has the best effect and the fastest reaction rate,which can reduce the viscosity of ASP producted water from 9.7mPa·s to 1.4mPa·s in 10 minutes,viscosity rate reached 85.5%.By further studying on ozone we found,when the pH of water sample was 10,the ozone ventilation was 5L/min,temperature is 40℃ the oxidation effect would be best,the viscosity reduction rate reached 89.1%and the COD removal rate reached 37.4%.By analyzing the oxidation effect after adding the hydroxyl radical inhibitor,we make sure that the indirect oxidation was dominant.On the base of these,we detected the intermediate products of polyacrylamide oxidation by HPLC.When ozone decomposed in water,it would product the hydroxyl radical,HPAM breaked down to produce acrylamide because of the action of hydroxyl radical,and the acrylamide was further oxidized to inorganic substance.By adjusting the appropriate reflux ratio,the optimal reflux ratio was adjusted.When the optimum reflux ratio was 5,the viscosity of produced water decreased from 8.5mPa-s to 1.8mPa-s,the removal rate reached 78.8%.By comparing the processing effect of different process combination sequence,we got that the best technological process is Microbial reactor、Advanced oxidation test device、Cyclone flotation separation device,the removal rate of suspended solids and oil content reached 94.3%and 98.2%.