Fluid migration within different lithology samples from the UKGEOS-Glasgow

To further explore the potential of shallow mine heat energy to the energy supply decarbonisation, it is essential to have a good understanding of the subsurface systems. We have used samples from the UKGEOS – Glasgow GGC01 borehole with a scope to characterise the material and explore the fluid migration within the different lithologies (interlayered sandstones and mudstones). The laboratory-scale experimental approach consists of a combined used of X-ray and Neutron Tomographies. These non-destructive tools have different sensitivities and resolutions. X-ray tomography (3D analysis) images have revealed the different lithologies, textural spatial differences due to deposition and natural or lab-induced fractures within the tested material. Individual seams or network of seams, all characterised by lower density material, are visualised in some of the samples. Neutron tomography (3D analysis) images have indicated that these seams absorbed more water after flow experiments in some of the samples. The same observation applies to local patches of low-density material within the samples. We have carried out High Speed Neutron tomography to capture water displacement within samples containing lab-induced fractures during flow experiments (4D analysis). Results have shown that within those samples fracture permeability dominates matrix permeability.