页岩气开发中压裂返排液的水质污染特征研究

页岩气压裂返排液成分复杂,为了解页岩气开采过程中压裂返排液的污染情况,对四川某页岩气典型井场不同时期的压裂返排液污染物组成进行了分析,采用超滤膜法测定溶解性有机物(DOM)相对分子质量分布特性,通过建立水质矩阵开展污染特性评价,并进行了综合生态毒性研究。结果表明,该区域不同时期压裂返排液中污染物特征相似,主要污染因子为总有机碳(TOC)和氯离子,并且生物毒性高、可生化性差。研究结果可为该区域压裂返排液处理技术的选择提供参考。

On the organic pollutants and molecular weight distribution in the HFFW of shale gas in Sichuan

The given paper takes it as its chief goal to make a detailed analysis of the composition of the hydraulic fracturing back-flow water(HFFW)of the shale gas in the various mining periods in Sichuan so as to clarify the DOM molecular weight distribution features.To achieve the purpose,we have conducted a comprehensive ecotoxicity experiment and the pollution feature evaluation.The results of our experiment and pollution feature evaluation reveal that:The composition of the back-flow water in different periods of shale gas turn out to be similar,though somewhat different in pollution load.More specifically speaking,the concentration of TDS tends to increase with time,whereas the Cl-concentration rate tends to be regular in the early-return of the polluted water(21500 mg/L)CN-L(poisoning)>CN-E(microtoxic).Among the said poisonous components,daphnia magna tends to be highly toxic in the ecological toxicity level.Besides,the polluted water in different periods of the region proves to be poor in biodegradability in the descending order of CN-L>CN-M>CN-E,which cannot be treated directly biologically.Therefore,a series of comprehensive treatment methods are recommended to deal with the problem.