Remote hydraulic fracturing at weak interfaces

Hydraulic fracturing experimental studies suggest that low viscous fluid injection leads to complex fracture morphology. A complex fracture network is more desirable for producing geoenergy more effectively. However, the precise impacts of low viscous fluid on the fracture nucleation and evolution are unknown. Here, we focused on the local variation in Biot’s coefficient, which is prevalent in hard rocks, and analyzed how the tensile stress redistributes in the presence of weak interfaces such as grain boundaries or natural fractures. We found that fracture nucleation at weak interfaces becomes more favorable under certain Biot’s coefficient contrast and fluid viscosity. Our numerical simulations demonstrate that low viscous fluid injection can fracture remote interfaces without initiating fractures at the injection point. These findings suggest that we can possibly engineer a reservoir stimulation protocol by combining low viscous fluid injection and applying low injection pressure to tight formations such as granitic geothermal systems.