Gas well integrity and methane migration: evaluation of published evidence during shale-gas development in the USA
Gas well integrity and methane migration: evaluation of published evidence during shale-gas development in the USA
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DOI：
10.1007/s10040-020-02116-y
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发表时间：
2020-02-26
影响因子：
2.8
通讯作者：
Engelder, Terry
中科院分区：
文献类型：
--
作者：
Hammond, Patrick A.;Wen, Tao;Engelder, Terry
仅在美国，可能就有100多万口井使用水力压裂技术完成；然而，很少有案例研究探索甲烷迁移对水资源的影响。这项研究评估了美国环保局发起的三项调查的结果，随后在宾夕法尼亚州迪莫克、德克萨斯州帕克-胡德县和怀俄明州Pavilion发表的研究以及宾夕法尼亚州东北部Sugar Run完成的另一项研究中进行了描述。此外，对宾夕法尼亚州的肖斯角、西弗吉尼亚州的杰克逊县、科罗拉多州的加菲尔德县和俄亥俄州的班布里奇的早期调查进行了总结。事故的最常见原因是油井中存在生产套管的非胶结部分，使天然气能够从中等深度向浅层淡水含水层流动。在三个案例中，主要水泥顶部(TOC)深度不足也是造成影响的原因之一。甲烷的来源最好是通过对生产套管、环空和水井样品的同位素分析来确定。在迪莫克，在补救行动完成后，一些同位素特征随着时间的推移而变化。在帕克-胡德县，影响与气井活动无关，也需要惰性气体分析来确定天然气的来源。在Pavillion，水井中甲烷的最大浓度是
More than 1 million wells may have been completed using hydraulic fracturing techniques in the USA alone; however, there have been few case studies exploring the impacts on water resources due to methane migration. This study evaluated the results of three investigations initiated by the US Environmental Protection Agency, that were subsequently described in published studies at Dimock in Pennsylvania, Parker-Hood County in Texas, and Pavillion in Wyoming, as well as another study completed at Sugar Run in northeast Pennsylvania. In addition, earlier investigations at Shaws Corner in Pennsylvania, Jackson County in West Virginia, Garfield County in Colorado, and Bainbridge in Ohio are summarized. The most common cause of incidents was the presence of uncemented sections of production casings in wells that allowed gas migration from intermediate depths to shallow freshwater aquifers. In three cases, an inadequate depth of the primary top of cement (TOC) also contributed to impacts. Sources of methane were best identified through analyses of isotopes on samples from production casings, annular spaces, and water wells. In Dimock, some isotope signatures changed with time, after the completion of remedial actions. In Parker-Hood County, where impacts were not related to gas well activity, noble gas analyses were also needed to determine the source of gas. At Pavillion, where maximum methane concentrations in water wells were