The role of fault and fracture networks to de- risk geological leakage from subsurface CO₂ storage sites

To verify successful long-term CO2 storage, it is critical to improve our understanding of leakage along natural faults and fractures within the primary caprock. In the proximity of a fault zone, interactions between multiple fracture sets can create complex networks which can play a fundamental role in fluid transport properties within the rock mass. Being able to fully characterise fault and fracture networks, in terms of fracture density, connectivity, aperture size and stress regime, can allow us to more accurately identify, analyse and model the bulk properties (e.g. transport, strength, anisotropy) and, therefore sealing behaviour, of faulted and fractured geological storage sites. Here, we present an integrated workflow which combines laboratory measurements of single fracture permeability with outcrop-scale analysis of fault and fracture networks occurring in reservoir/caprock sections. These data are then used to develop a hydromechanical model to upscale laboratory tests to network-scale and potentially to reservoir-scale, verified against in-situ fault permeability data, where available.