Chemical Flooding Sewage Treatment And Oxidative Degradation Mechanism Research

At present,most of the domestic oilfield development has entered the middle and late stages,and chemical drive replacement means such as polymers,surface activators and alkalis are used to improve the recovery rate,resulting in complex water quality composition of the recovery fluid and serious excess of suspended solids content and oil content,which poses a greater challenge to the separation and treatment of chemical flooding sewage and re-injection in oilfield.However,the optimal process parameters of deep aeration are still vague,and the mechanism of deep aeration and oxidative degradation mechanism of HPAM aeration are still unclear.Firstly,the experimental conditions of deep aeration process for chemically flooding sewage treatment in Block J were selected,air was chosen as the aeration gas,the optimal aeration time was 35?55min,the optimal aeration temperature range was 35?65?,the optimal aeration volume was 1.5L/min;the optimal aeration device diameter/height ratio was1/5,the optimal aeration level height was at the 10ml scale,the number of aeration outlet pipes was 3 The oil content and suspended matter content can reach the target of?30mg/L to meet the requirements of sewage re-injection.Secondly,EDS technology was used to analyze the changes of the components of suspended solids in the chemically driven sewage before and after the treatment of the deep aeration process:the suspended solids in the raw water mainly consisted of three elements,C,O and Na,and were mainly divided into organic matter with HAPM and oil droplets as the main components and inorganic matter with Na as the main component;in the initial stage of deep aeration,oxygenation and mass transfer were mainly carried out in the sewage,and the content of C element increased;in the deep aeration in the later stage,the polymer oxidative degradation,the content of C,O and Na elements dissolved in the effluent in the form of sodium salts decreases,and the content of Mg,Ca,Si and other elements in the form of silicate type increases.Thirdly,the dynamic evolution of suspended solids and the spatial morphology of polyacrylamide at different times in the process of deep aeration was studied,and the mechanism of deep aeration was determined:the oxidative degradation of polyacrylamide with cross-linked network structure was spherical particles;Under the bridging action of Mg²⁺and Ca²⁺,the negatively charged hydrolytic oligomer effectively reduces the electrostatic repulsion force between it and suspended solid particles or oil droplets.Under the synergistic action of each component,the floc structure is formed.Under the action of air flotation,it rises to the liquid surface to form scum and is removed.Therefore,the suspended solid content and oil content are greatly reduced.Finally,the oxidative degradation of HPAM under aeration conditions was studied by reaction kinetic simulation:the reaction paths of the initial radicals in the system were summarized,and the oxidative degradation of HPAM by aeration was determined to include the hydrogen grabbing reaction on the molecular chain,the cyclization reaction of the side chain amide and carboxyl groups,the breakage of the side chain groups and the main carbon chain,and the reaction of the derived products;the effects of aeration temperature,polymerization degree,·OH,and ozone content on the oxidative degradation of HPAM were further studied.The effects of aeration temperature,degree of polymerization,·OH,and ozone content on the oxidative degradation of HPAM by aeration were further investigated.The above study is a good guideline for the selection of process parameters and the development of aeration devices for oilfield field sewage treatment,which also improves the sewage treatment efficiency and saves the treatment cost,and provides a theoretical basis for the aeration treatment of chemically flooding sewage in oilfield field.