Modelling of fluid pressure migration in a pressure sensitive fault zone subject to cyclic injection and implications for injection-induced seismicity

SUMMARY Fault zones often serve as the major fluid pathways in a variety of geo-energy systems, such deep geothermal systems. However, injection-induced instability faults can sometimes lead to large-magnitude earthquakes. Cyclic injection has thus been proposed an alternative protocol better manage and mitigate associated seismic risks. The risks seismicity depend primarily on extent magnitude pressure perturbation. When is injected into fault zone, local permeability will be enhanced, which turn promotes migration along fault. This nonlinear process further complicated during cyclic via alternating pressure. In this study, both numerical analytical modelling are conducted investigate zone with sensitive permeability, changes function effective stress. match laboratory-scale experimental field-scale results verifies accuracy model. parametric study reveals that attenuation, quantified by amplitude ratio phase shift, enhanced lower initial smaller stress sensitivity coefficient shorter period cycle (i.e. higher frequency). Besides, negligible effect attenuation. We also discuss implications our for less amenable far-field hazard post shut-in seismicity.