长宁页岩气压裂返排液水质特征及化学絮凝处理

Water Quality Characteristics and Chemical Flocculation Treatment of Fracturing Waste Fluid From Changning Shale Gas Reservoir

以四川长宁页岩气开发示范区为研究对象,分析了压裂后返排液水质特征,通过室内试验,选择了四种絮凝剂探究化学絮凝效果,研究表明,综合考虑处理后COD去除率、水样pH和浊度,针对高浓度返排液选择2000 mg·L-1的PFS作为最佳絮凝剂,COD除去率达98.75%;针对低浓度返排液选择1500 mg·L-1的PAC作为最佳絮凝剂,COD除去率达85.83%。

Chemical flocculation method is an important technical means to treat the shale gas fracturing waste fluid.Aiming at the problem that the treatment effect of chemical flocculation process in different shale gas development blocks was quite different,taking Changning shale gas development demonstration zone in Sichuan as the research object,the water quality characteristics of back-flow fluid after fracturing were analyzed.Through laboratory tests,four kinds of flocculants were used to study the effect of chemical flocculation.The results showed that considering the removal rate of COD,pH and turbidity of water samples after treatment,the best flocculant was PFS with the removal rate of 98.75%for high concentration of fracturing waste fluid and PAC with the removal rate of 85.83%for low concentration of fracturing waste fluid.