Searching for anomalous methane in shallow groundwater near shale gas wells
Searching for anomalous methane in shallow groundwater near shale gas wells
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DOI：
10.1016/j.jconhyd.2016.10.005
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发表时间：
2016-12-01
影响因子：
3.6
通讯作者：
Brantley, Susan L.
中科院分区：
文献类型：
--
作者：
Li, Zhenhui;You, Cheng;Brantley, Susan L.
自19世纪以来，天然气一直是从钻入常规储层的威尔斯井中提取的。如今，天然气也可以通过大容量水力压裂（HVHF）从页岩中提取。这些威尔斯井有时会泄漏甲烷，必须用水泥重新密封。一些研究人员认为，页岩气威尔斯井附近的地下水中甲烷浓度C会增加，“跟踪“威尔斯井比传统威尔斯井泄漏更多。我们开发的技术，以挖掘数据集的地下水化学在宾夕法尼亚州的乡镇污染已报告。在整个地区，在私人浅水井威尔斯中测得的C值随着靠近断层和常规威尔斯井而增加，但页岩气井则不然。然而，在小的分区中，C随着靠近一些页岩气威尔斯井而增加。数据挖掘被用来映射一些热点，其中C与到断层和威尔斯的距离显著相关。在热点附近，132口页岩气威尔斯井中有3口（约占2%）和15口常规威尔斯井中有4口（27%）与断层相交，据报告，这些井未下套管或未注水泥。这些结果表明，即使这些数据技术不建立因果关系，他们可以阐明天然甲烷排放的控制沿着断层，并可能对气井建设的影响。(C)2016爱思唯尔B.V.保留所有权利。
Since the 1800s, natural gas has been extracted from wells drilled into conventional reservoirs. Today, gas is also extracted from shale using high-volume hydraulic fracturing (HVHF). These wells sometimes leak methane and must be re-sealed with cement. Some researchers argue that methane concentrations, C, increase in groundwater near shale-gas wells and that "tracked"wells leak more than conventional wells. We developed techniques to mine datasets of groundwater chemistry in Pennsylvania townships where contamination had been reported. Values of C measured in shallow private water wells were discovered to increase with proximity to faults and to conventional, but not shale-gas, wells in the entire area. However, in small subareas, C increased with proximity to some shale-gas wells. Data mining was used to map a few hotspots where C significantly correlates with distance to faults and gas wells. Near the hotspots, 3 out of 132 shale-gas wells (similar to 2%) and 4 out of 15 conventional wells (27%) intersect faults at depths where they are reported to be uncased or uncemented. These results demonstrate that even though these data techniques do not establish causation, they can elucidate the controls on natural methane emission along faults and may have implications for gas well construction. (C) 2016 Elsevier B.V. All rights reserved.