Pore-scale assessment of subsurface carbon storage potential: implications for the UK Geoenergy Observatories project

The growing importance of subsurface carbon storage for tackling anthropogenic carbon emissions requires new ideas to improve the rate and cost of carbon capture and storage (CCS) project development and implementation. We assessed sandstones from the UK Geoenergy Observatories (UKGEOS) site in Glasgow, UK and the Wilmslow Sandstone Formation (WSF) in Cumbria, UK at the pore scale to indicate suitability for further assessment as CCS reservoirs. We measured porosity, permeability and other pore geometry characteristics using digital rock physics techniques on microcomputed tomographic images of core material from each site. We found the Glasgow material to be unsuitable for CCS due to very low porosity (up to 1.65%), whereas the WSF material showed connected porosity up to 26.3% and permeabilities up to 6040 mD. Our results support the presence of a percolation threshold at 10% total porosity, introducing near full connectivity. We found total porosity varies with permeability with an exponent of 3.19. This provides a reason to assume near full connectivity in sedimentary samples showing porosities above this threshold without the need for expensive and time-consuming analyses. Supplementary material: Information about the boreholes sampled in this study, additional well logs of boreholes and a summary of the supporting data plotted throughout this article from literature are available at https://doi.org/10.6084/m9.figshare.c.5260074 Thematic collection: This article is part of the Geoscience for CO2 storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage