CO2 reactive fracturing creates stress-resistant permeability by coupling fracture generation and chemical roughening

Abstract Permeability enhancement in subsurface reservoirs is commonly achieved by hydraulic or CO 2 -based fracturing, yet the resulting benefits are often short-lived because fracture apertures progressively close as effective stress increases. This limitation constrains the long-term performance of geothermal, carbon storage, and other subsurface energy systems. Here, we introduce CO 2 reactive fracturing, a coupled hydraulic–chemical stimulation strategy that creates stress-resistant flow paths by integrating CO 2 -driven fracture initiation with localized chemical roughening of fracture surfaces. Using true-triaxial stress experiments on porous andesitic tuff, we show that viscosity-controlled water-assisted CO 2 fracturing alone predominantly generates tensile, mated fractures with limited aperture stability. In contrast, introducing a shear-thinning reactive assisting fluid composed of a chelating agent and a minor fluoride source confines flow to fractures and induces localized dissolution of aluminosilicate and Fe-bearing minerals. This process increases fracture-surface roughness while suppressing reactive-fluid infiltration into the surrounding matrix, thereby enhancing aperture retention and sustaining permeability under elevated effective stress. Our results establish a general mechanism by which fracture generation and chemically induced roughening act synergistically to produce durable permeability, with broad implications for subsurface energy production and carbon storage applications.