Organic and inorganic composition and microbiology of produced waters from Pennsylvania shale gas wells
Organic and inorganic composition and microbiology of produced waters from Pennsylvania shale gas wells
复制标题
DOI：
10.1016/j.apgeochem.2015.04.011
复制
发表时间：
2015-09-01
影响因子：
3.4
通讯作者：
Lorah, Michelle M.
中科院分区：
文献类型：
--
作者：
Akob, Denise M.;Cozzarelli, Isabelle M.;Lorah, Michelle M.
水力压裂页岩正在成为美国日益重要的天然气生产来源。众所周知，该过程每天可产生420加仑的产出水（PW），但产量取决于地层和单个水力裂缝的特征。页岩水力压裂的PW由注入的压裂液和天然地层水组成，其比例随时间而变化。在整个宾夕法尼亚州，页岩气的生产正在蓬勃发展；因此，评估PW化学和微生物学在这一地理跨度中的变异性是很重要的。我们对宾夕法尼亚州中北部13口页岩气井的PW样品中的无机和有机化学成分和微生物群落进行了定量分析。微生物丰度普遍较低（66-9400个细胞/mL）。非挥发性溶解有机碳（NVDOC）相对于典型浅层地下水较高（7-31 mg/L），有机酸阴离子（如乙酸、甲酸和丙酮酸）的存在表明微生物活性。在4个样品中检测到挥发性有机化合物（VOCs）（范围为1 ~ 11.7 μ g/L）： Burket样品中检测到苯和甲苯，两个Marcellus样品中检测到甲苯，一个Marcellus样品中检测到四氯乙烯（PCE）。挥发性有机化合物既可以是自然产生的，也可以来自工业活动，这使得挥发性有机化合物的来源不清楚。尽管在水力压裂过程中添加了杀菌剂，但从PW样品中培养出了产生h2s、发酵和产甲烷的细菌。可培养细菌的存在与盐度或位置无关；虽然有机化合物浓度和生产时间与微生物活性相关。有趣的是，研究人员发现，与无机化学成分不同，在13口取样井中，PW的有机化学成分和微生物活力变化很大，这对这些流体的再利用和处理具有重要意义。Elsevier Ltd.出版。
Hydraulically fractured shales are becoming an increasingly important source of natural gas production in the United States. This process has been known to create up to 420 gallons of produced water (PW) per day, but the volume varies depending on the formation, and the characteristics of individual hydraulic fracture. PW from hydraulic fracturing of shales are comprised of injected fracturing fluids and natural formation waters in proportions that change over time. Across the state of Pennsylvania, shale gas production is booming; therefore, it is important to assess the variability in PW chemistry and microbiology across this geographical span. We quantified the inorganic and organic chemical composition and microbial communities in PW samples from 13 shale gas wells in north central Pennsylvania. Microbial abundance was generally low (66-9400 cells/mL). Non-volatile dissolved organic carbon (NVDOC) was high (7-31 mg/L) relative to typical shallow groundwater, and the presence of organic acid anions (e.g., acetate, formate, and pyruvate) indicated microbial activity. Volatile organic compounds (VOCs) were detected in four samples (similar to 1 to 11.7 mu g/L): benzene and toluene in the Burket sample, toluene in two Marcellus samples, and tetrachloroethylene (PCE) in one Marcellus sample. VOCs can be either naturally occurring or from industrial activity, making the source of VOCs unclear. Despite the addition of biocides during hydraulic fracturing, H2S-producing, fermenting, and methanogenic bacteria were cultured from PW samples. The presence of culturable bacteria was not associated with salinity or location; although organic compound concentrations and time in production were correlated with microbial activity. Interestingly, we found that unlike the inorganic chemistry, PW organic chemistry and microbial viability were highly variable across the 13 wells sampled, which can have important implications for the reuse and handling of these fluids. Published by Elsevier Ltd.