The importance of fracture-healing on the deformation of fluid-filled layered systems

Understanding the fracturing-healing-refracturing cycle is a fundamental part of studying the deformation dynamics and the permeability evolution of rock systems. Previous studies, however, have not examined the influence of healing i.e. fracture-closure through vein formation and the mechanical properties of the "healed" fractures (veins) on the rock deformation. We present results from a two-dimensional coupled hydro-mechanical model which simulates large time and spatial scale dynamic fracturing and healing of a porous medium under the influence of gravity, tectonic stretching and elevated fluid pressures. Our results show that healing decreases the local porosity, and that the veins' strength is more important than their elastic modulus in influencing the deformation and the evolving patterns. Hard veins make the aggregate progressively stronger, results in an overall healing of the system, limited fracturing and thus fluid flow, greater stresses and delayed fracture saturation. Weak veins make the system weaker in which refracturing of the healed bonds is the dominant process that creates more open fractures and thus increases the permeability. These results provide clues for the importance of the veins' mechanical properties and can enhance our understanding of the deformation dynamics and the permeability evolution of the rock systems.