Geological characterization and assessment of confining layer potential of the Upper Ordovician Utica Shale, Michigan Basin, USA

The objective of this study was to investigate the geological controls on stratigraphic and lithologic variability in the Ordovician Utica Shale and related Collingwood Member in the Michigan Basin in order to assess CO2 sequestration cap rock (seal) potential, including petrophysical properties and mechanical fracture responses. Twelve conventional cores and hundreds of modern well logs from the Michigan Basin were analyzed to correlate and calibrate wireline log signatures with whole-rock mineral composition (from X-ray diffraction analysis) and mechanical properties (from core analysis) to identify brittle, fracture-prone zones, and to validate the Utica Shale as a regional geologic seal. Analysis using scanning electron microscopy with Quantitative Evaluation of Minerals by Scanning Electron Microscope (QEMSCAN (R)) software was employed to image pores and for quantitative analysis of mineralogy, texture, and porosity. Mercury injection capillary pressure and triaxial strength testing was conducted to assess petrophysical properties and mechanical responses. The results suggest the Utica Shale could reliably contain upwards of 1500 m of buoyant, supercritical CO2 stored in underlying Cambrian and Ordovician reservoirs.