Experimental Investigation of Fracture–Matrix Flow Using CT Imaging

Fracture–matrix fluid interaction is receiving growing attention in the energy sector, as it commonly occurs during hydraulic fracturing and injection operations designed to boost production or enablesubsurface storage. This study examines how fluid flow evolves in sandstone reservoirs as fractures developand interact with the surrounding matrix. Using a triaxial core flooding apparatus, we conducted experimentsunder coupled hydraulic and mechanical loading, capturing real-time pressure, flow, and stress data. MicroCT imaging enabled direct visualisation of fracture initiation and propagation at the pore scale. The resultingdataset provides a basis to investigate the evolving fracture-matrix geometry and to quantify the interactionof fluid flow between fracture and matrix system, which will be used in the calibration of fracture-matrixpore network models. An important finding is that the fracture permeability is a function of matrix permeability in the Fracture–matrix coexisting system, there is an inverse correlation between the initial matrixpermeability and the dimensionless fractured-to-unfractured permeability ratio (kD), underscoring the control exerted by original rock properties. Despite overall permeability increases post-fracturing, flow remainsintensely concentrated along fracture paths, with minimal contribution from the matrix. These resultsdemonstrate the importance of experimental methods in quantifying fracture-matrix interactions, improvingthe understanding of fluid flow mechanism in fractured porous media during hydraulic fracturing and injection operations.