Subsurface stratigraphic analysis of Upper Cretaceous rocks, southeastern flank of the Williston Basin, North and South Dakota

Baird, J.K.; Dyman, T.S.

doi:10.3133/ofr93335

Cited by 2 publications

(2 citation statements)

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“…The locations of sedimentary basins in the United States containing black shales are shown in Figure . The overburden rocks above the targeted black shales are predominantly fine‐grained (e.g., shale or mudstone; Figure ) or mixtures of fine‐grained and coarse‐grained rocks (e.g., shaly sandstone; Sandberg ; Kiteley ; Baird and Dyman ; Ryder et al , , ; Swezey , ).…”

Section: Hydrogeological Setting Of Black Shales Within Sedimentary Bmentioning

confidence: 99%

“…That is, k eff is only 5% of the permeability of sandstone, even though sandstone comprises 98% of the hypothetical section. More commonly, stratigraphy above black shales is dominated by fine‐grained rocks (e.g., shales and mudstones) and therefore, multiple, sometimes thick, low‐ k layers may limit vertical flow rates (Sandberg ; Baird and Dyman ; Ryder et al , , ). Two examples of shale‐dominated overburden are shown in Figure .…”

Section: Constraints On Permeabilitymentioning

confidence: 99%

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Constraints on Upward Migration of Hydraulic Fracturing Fluid and Brine

Flewelling

Sharma

2013

Groundwater

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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. Some recent studies have suggested that such upward migration can be large and that timescales for migration can be as short as a few years. In this article, we discuss the physical constraints on upward fluid migration from black shales (e.g., the Marcellus, Bakken, and Eagle Ford) to shallow aquifers, taking into account the potential changes to the subsurface brought about by HF. Our review of the literature indicates that HF affects a very limited portion of the entire thickness of the overlying bedrock and therefore, is unable to create direct hydraulic communication between black shales and shallow aquifers via induced fractures. As a result, upward migration of HF fluid and brine is controlled by preexisting hydraulic gradients and bedrock permeability. We show that in cases where there is an upward gradient, permeability is low, upward flow rates are low, and mean travel times are long (often >106 years). 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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