Organic sulfur fingerprint indicates continued injection fluid signature 10 months after hydraulic fracturing
Organic sulfur fingerprint indicates continued injection fluid signature 10 months after hydraulic fracturing
复制标题
有机硫指纹表明水力压裂后 10 个月持续注入流体特征
DOI：
10.1039/c8em00331a
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
Gonsior, Michael
中科院分区：
文献类型：
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作者：
Luek, Jenna L.;Harir, Mourad;Schmitt-Kopplin, Philippe;Mouser, Paula J.;Gonsior, Michael
水力压裂需要注入大量流体从低渗透非常规资源（如页岩、煤层气）中提取油气，从而产生大量高度复杂和多变的废液。在美国西弗吉尼亚州Morgantown的Marcellus页岩能源与环境实验室（MSEEL）采集了两口水力压裂井的页岩气流体样本，并使用超高分辨率质谱分析了溶解有机硫（DOS）储层。使用非目标方法，对指定DOS公式的离子进行分析，以确定主要的DOS类别，描述它们的时间趋势及其含义，并描述较大的DOS池的分子特征。返排中有机硫化合物的平均分子量降低，在采出水中最低。根据精确的质量和同源分布匹配，主要的DOS类别被推定为可能作为压裂液添加剂注入的硫酸醇和乙醇乙氧基硫酸表面活性剂。在首次注入水力压裂液10个月后，这种DOS特征就被识别出来了，页岩井基因组和宏基因组中没有编码醇乙氧基硫酸酯降解蛋白（如硫酸酯酶）的基因，这表明这些添加剂不容易被生物降解，可能继续作为注入流体的化学特征。了解页岩井中有机硫化合物的多样性、不稳定性和命运对于生产井的工程设计、防止天然气酸化以及了解意外流体释放到环境中的后果非常重要。DOS的多样性，特别是极性化合物的多样性，需要进一步研究，以确定所识别的特征和时间模式是在所分析的井中所独有的，还是代表了在其他地层和其他操作条件下发现的更广泛的模式。
Hydraulic fracturing requires the injection of large volumes of fluid to extract oil and gas from low permeability unconventional resources (e.g., shale, coalbed methane), resulting in the production of large volumes of highly complex and variable waste fluids. Shale gas fluid samples were collected from two hydraulically fractured wells in Morgantown, WV, USA at the Marcellus Shale Energy and Environment Laboratory (MSEEL) and analyzed using ultrahigh resolution mass spectrometry to investigate the dissolved organic sulfur (DOS) pool. Using a non-targeted approach, ions assigned DOS formulas were analyzed to identify dominant DOS classes, describe their temporal trends and their implications, and describe the molecular characteristics of the larger DOS pool. The average molecular weight of organic sulfur compounds in flowback decreased and was lowest in produced waters. The dominant DOS classes were putatively assigned to alcohol sulfate and alcohol ethoxysulfate surfactants, likely injected as fracturing fluid additives, on the basis of exact mass and homolog distribution matching. This DOS signature was identifiable 10 months after the initial injection of hydraulic fracturing fluid, and an absence of genes that code for alcohol ethoxysulfate degrading proteins (e.g., sulfatases) in the shale well genomes and metagenomes support that these additives are not readily degraded biologically and may continue to act as a chemical signature of the injected fluid. Understanding the diversity, lability, and fate of organic sulfur compounds in shale wells is important for engineering productive wells and preventing gas souring as well as understanding the consequences of unintended fluid release to the environment. The diversity of DOS, particularly more polar compounds, needs further investigation to determine if the identified characteristics and temporal patterns are unique to the analyzed wells or represent broader patterns found in other formations and under other operating conditions.