The application of elemental geochemistry to UK onshore unconventional plays

Abstract

AbstractThe Namurian and Westphalian sequences from the onshore well Scaftworth-B2, located in the Gainsborough Trough, central England, have been analysed for whole-rock inorganic geochemical data via inductively coupled plasma optical emission spectrometry (ICP-OES) and mass spectrometry (MS). The changes within key elements, and elemental ratios, results in a chemostratigraphic zonation scheme consisting of eight chemostratigraphic sequences and 13 chemostratigraphic packages, providing the type zonation for the Bowland Shale and overlying formations. Mineralogical data are provided by whole rock X-ray diffraction (XRD) and are used to calibrate the mineral modelling in order to generate a modelled mineral log for the study well. Furthermore, the modelled mineralogy is then used to calculate a relative brittleness for the samples, which can then be collaborated with traditional rock properties data at a later date. Elemental data can also be used to model the relative abundance of detrital quartz and biogenic silica; while total silicon is detected by ICP, biogenic silica is not detected by XRD owing to its amorphous nature. Enrichment factors calculated from the inorganic elemental data suggest that the sediment was deposited in an unrestricted marine setting, which experienced periods of anoxia.