Effect of a Porous Limestone’s Microstructure on its Mechanical Behaviour and Strain Localisation Modes Under Triaxial Load

Abstract In energy transition, reservoir rocks are selected for CO 2 storage due to their high porosity and permeability; yet their sequestration potential still needs to be determined. Triaxial compression tests combined with X-ray tomography offer a useful tool for understanding the role of the microstructure on the stain accommodation. The aim is to build 3D deformation maps at a sub-millimetric gauge length and identify local mechanisms responsible for the mechanical response of a specific limestone. Different confining pressures are imposed within the cell, and two samples of the same rock at different porosities are tested for each of them. A transition from brittle to ductile behavior is observed while the confining pressure increases. Despite the deformation remaining quite concentrated in the most porous areas at low confining pressure, the porous sample shows a greater tendency to spread it than the dense sample.