Using core and outcrop analogues to predict flow pathways in the subsurface: examples from the Triassic sandstones of north Cheshire, UK

Abstract. Borehole core provides detailed vertical data which is used to interpret subsurface sand body architectures, but assumptions are made on the relationship between the lateral and vertical thickness, and the interconnectivity of units. The sedimentological complexity of the Sherwood Sandstone Group succession in this area, passing between aeolian and fluvial packages creates local- to regional-scale heterogeneities which will impact flow pathways within the rockmass. Measured thickness in boreholes might represent an architectural element's true maximum thickness or more likely, a partial thickness as a result of incision by overlying facies types or as a result of the borehole sitting towards the margins of individual elements (e.g. tapering margin of channel elements). Length and thickness data were measured from a suite of primary core data and secondary published outcrop studies in north-west England. The addition of outcrop studies in combination with the borehole data provides a dataset from which the likely lateral extent of the architectural frameworks within the Triassic sandstones can be extrapolated. The interpreted high resolution sub-seismic architecture contributes to an increased understanding of flow pathways and the effect these may have on groundwater as well as sustainable energy technologies such as low-temperature geothermal aquifers, carbon storage and energy storage.