Constraints on upward migration of hydraulic fracturing fluid and brine.
Bottom Line: Recent increases in the use of hydraulic fracturing (HF) to aid extraction of oil and gas from black shales have raised concerns regarding potential environmental effects associated with predictions of upward migration of HF fluid and brine.Consequently, the recently proposed rapid upward migration of brine and HF fluid, predicted to occur as a result of increased HF activity, does not appear to be physically plausible.Unrealistically high estimates of upward flow are the result of invalid assumptions about HF and the hydrogeology of sedimentary basins.
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Mentions: Sedimentary basins occur around the globe, including many in the United States (Hunt 1990). The thickness of sediment in U.S. basins varies depending on their history of formation, uplift, and subsequent erosion; in some cases, sediment thicknesses in excess of 10 km accumulated during periods of deposition (e.g., in portions of the Appalachian Basin during the Permian—circa 300 to 250 million years ago; Garven et al. 1993; Rowan 2006). The locations of sedimentary basins in the United States containing black shales are shown in Figure 1. The overburden rocks above the targeted black shales are predominantly fine-grained (e.g., shale or mudstone; Figure 2) or mixtures of fine-grained and coarse-grained rocks (e.g., shaly sandstone; Sandberg 1962; Kiteley 1978; Baird and Dyman 1993; Ryder et al. 2008, 2009, 2012; Swezey 2008, 2009).
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