电子束辐照技术降解油田采出水聚丙烯酰胺实验研究

Experimental Study on the Degradation of Polyacrylamide in Oilfield Produced Water by Electron Beam Irradiation Technology

大庆油田聚驱采出水中含有较高浓度的部分水解聚丙酰胺(HPAM),造成污水黏度高,油水分离难度大,需开展电子束辐照技术对去离子水溶液和油田含聚污水中的HPAM降解效果进行实验研究。实验结果表明:电子束辐照可大幅降低HPAM去离子水溶液和油田含聚污水的黏度;有效降解去离子水溶液中的HPAM,部分降解油田含聚污水中的HPAM,若要将含聚污水中的HPAM全部矿化则需更高的辐照剂量。电子束辐照吸收剂量分别为5、10 kGy时,HPAM去离子水溶液(相对分子质量分别为LH 2500万、1200万~1600万)中HPAM浓度的去除率分别为80.6%和35.7%与90.6%和76.3%,溶液黏度均降到1.1 mPa·s;电子束辐照吸收剂量分别为5、10 kGy时,油田两种含聚污水中HPAM浓度去除率分别为14.2%和19.8%与26.4%和31.6%,污水黏度均降到1.1 mPa·s,接近于纯水黏度;电子束辐照降解HPAM的主要作用机制是水分子受辐照后产生羟基自由基氧化;电子束辐照可破坏HPAM分子结构,产生氨氮、含双键的聚合物碎片等降解产物。

The polymer flooding produced water in Daqing Oilfield contains a high concentration of partially hydrolyzed polyacrylamide(HPAM),resulting in high viscosity of wastewater and difficulty in oil-water separation.Experimental research on the effect of electron beam irradiation on the degradation of HPAM in deionized water solution and polymer wastewater in oilfield is carried out.The experimental results show that electron beam irradiation can greatly reduce the viscosity of HPAM deionized water solution and polymer wastewater in oilfield,and can effectively degrade HPAM in deionized water solution and partially degrade HPAM in polymer wastewater in oilfield.A higher irradiation dose is needed to fully mineralize HPAM in polymer wastewater.When the absorption dose of electron beam irradiation is 5 kGy and 10 kGy,respectively,the removal rates of HPAM concentration in HPAM deionized water solutions(relative molecular mass:LH25million,12 million~16 million)are 80.6%,35.7%and 90.6%,76.3%,respectively.The solution viscosity is reduced to 1.1 mPa·s.When the absorption dose of electron beam irradiation is 5 kGy and 10 kGy,respectively,the removal rates of HPAM concentration in the two kinds of oilfield polymer wastewater are 14.2%,19.8%,and 26.4%,31.6%,respectively.The viscosity is reduced to 1.1 mPa·s,which is close to pure water viscosity.The main mechanism of HPAM degradation by electron beam irradiation is the oxidation of hydroxyl radical produced by the irradiation of water molecules.The electron beam irradiation can destroy the molecular structure of HPAM and generate degradation products such as ammonia nitrogen and polymer fragments containing double bonds.