Fluid migration in low-permeability faults driven by decoupling of fault slip and opening

Understanding the response of faults to injection high-pressure fluids is important for several subsurface applications, example, geologic carbon sequestration or energy storage. Lab-based experiments suggest that fluid can activate fault slip and this lead increased transmission along low-permeability faults. Here we present in situ observations from a cross-borehole fluid-injection experiment shale-bearing fault, which show displacement occurring before fluid-pressure build-up. Comparing these with numerical models differing permeability evolution histories, find observed variation pressure best explained by change only after fails slips beyond pressurized area. Once migration occurs as result slip-induced increase, experiences further opening due decrease effective normal stress. We decoupling opening, leading rapid increase pressurization following initial slip, could be an efficient driver Decoupled failure, drives faults, according modelling borehole experiment.