Potential Contaminant Pathways from Hydraulically Fractured Shale Aquifers
Potential Contaminant Pathways from Hydraulically Fractured Shale Aquifers
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DOI：
10.1111/j.1745-6584.2012.00990.x
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发表时间：
2012-11
期刊：
影响因子：
2.6
通讯作者：
J. Saiers;E. Barth
中科院分区：
文献类型：
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作者：
J. Saiers;E. Barth
在最近的一篇文章中，T。Myers使用MODFLOW来检查马塞勒斯页岩（“马塞勒斯”）水力压裂对地下水流模式的影响。迈尔斯的模型包括一个代表马塞勒斯的地层，一个1500米的砂岩覆盖层和一个直接连接马塞勒斯和地表的高渗透性“裂缝”。迈尔斯进行稳态和瞬态地下水流模拟的情况下，没有和注入水平井（近似条件下，在水力刺激的页岩层），他检查了模型计算的敏感性，在页岩和上覆砂岩的水力传导性的变化。他的研究结果表明，水力压裂后，流动系统将在3至6年内达到新的平衡，他得出结论，水力压裂的水文应力可以在不到10年的时间内将压裂液和地层水平流输送到饮用水含水层（Myers，2012年）。我们认识到模型只代表现实的近似，但迈尔斯的建模框架忽略了关键的水文过程，歪曲了驱动地下水流的物理条件，并以过于严重和不必要的简化为基础。由于这些缺点，迈尔斯的研究结果不应该被解释为合理的预测的地下水流和污染物迁移的水力压裂的响应。在下面的段落中，我们详细阐述了迈尔斯模型的不足之处，并提出了替代方法，可以改善描述的地下水流和溶质运移期间和之后的马塞勒斯水力刺激。Myers假设地下水流动只通过充满水的空隙空间发生，而事实上，马塞勒斯和一些上覆的空隙空间
In a recent article, T. Myers used MODFLOW to examine the impacts of hydraulic fracturing of the Marcellus Shale (“the Marcellus”) on groundwater flow patterns. Myers’ model includes a layer representing the Marcellus, a 1500-m overburden of sandstone and one highpermeability “fracture” connecting the Marcellus directly to the surface. Myers conducts steady-state and transient groundwater flow simulations for scenarios without and with injection into a horizontal well (to approximate conditions during hydraulic stimulation of the shale layer), and he examines the sensitivity of the model calculations to changes in hydraulic conductivity of the shale and overlying sandstone. His results suggest the flow system would reach a new equilibrium in 3 to 6 years following hydraulic fracturing, and he concludes that the hydrologic stress of hydraulic fracturing could allow for advective transport of frac fluids and formation water to drinkingwater aquifers in less than 10 years (Myers 2012). We recognize models represent only approximations of reality, but Myers’ modeling framework neglects critical hydrologic processes, misrepresents physical conditions that drive groundwater flow, and is underpinned by simplifications that are too severe and unnecessary. Owing to these shortcomings, Myers’ findings should not be interpreted as reasonable predictions of the response of groundwater flow and contaminant migration to hydraulic fracturing. In the paragraphs below, we elaborate on the deficiencies of Myers’ model and suggest alternative approaches that could improve descriptions of groundwater flow and solute transport during and following hydraulic stimulation of the Marcellus. Myers assumes that groundwater flow occurs exclusively through water-filled void spaces, when, in fact, the void spaces of the Marcellus and some overlying