Fault Permeability and Strength Evolution Related to Fracturing and Healing Episodic Processes (Years to Millennia): the Role of Pressure Solution

It is well known that fluids flow through faults and fractures but it is also demonstrated that fault zones act as impermeable barriers. Consequently, one must consider that faults are successively open and closed paths for fluids. On the human-activity time scale (years to millennia), studies of the seismic cycle offer the possibility of making a model of such evolution. According to this model, seismic (or hydraulic) fracturing opens fluid paths almost instantaneously through the faults with associated weakening and post-fracturing creep processes. Fault healing processes then progressively close such fluid paths, associated with fault strengthening and fluid pressure recovery. Such transient behaviors have major consequences in the studies of: the evolution of permeability along faults with application tooil-field reservoir exploitation and fluid and waste storage