Investigating the Saturation State of Higher Strength Rock (HSR) by Geoelectrical Imaging at the Core Scale

This study demonstrates how the capacitive resistivity imaging (CRI) technique can be used at the laboratory scale to derive a spatially resolved 3D model of water content in a core sample of Higher Strength Rock (HSR). Understanding groundwater flow and the transport and retardation of any radionuclides in fractured HSR is a key research aim associated with the geological disposal of radioactive waste. Retardation and incorporation of radionuclides from groundwater into the surrounding rock mass is important for the safety case for a geological disposal facility (GDF) in HSR. For a rock with dual porosity, such retardation and incorporation may be enhanced if the radionuclides are able to diffuse from fractures that support advection into effectively stagnant porewater within the rock matrix. This diffusion is termed Rock Matrix Diffusion (RMD). Improved non-destructive estimation and spatial mapping of water content in HSR under “fresh rock” conditions may offer new insights in RMD research.