Hydraulic Properties and Microgeometry Evolution Accompanying Limestone Dissolution by Acidic Water

International audienceA reactive flow-through experiment by carbon dioxide-saturated water at the partial pressure of 0.1 MPa and room temperature was conducted on a porous limestone in order to identify the relationships between fluid chemistry, hydrodynamics and structural properties. Periodic imaging by non destructive X-ray microtomography allowed following the evolution of the core micro-geometry and fluid-rock interface in detail while its porosity and permeability increased due to dissolution. Several mechanisms were successively involved in the rapid permeability increase. Early in the experiment, the permeability increase was related to concomitant particle dissolution and displacement. Later on, permeability continued to rise due to solid-fluid interface smoothing and to pore connectivity increase