Laboratory friction-permeability response of rock fractures: a review and new insights

Friction-permeability response of rock fractures is a fundamental issue in developing geo-energy extraction and storage. This review aims to summarize and promote our understanding of friction-permeability relationships for rock fractures and to inspire us to create robust solutions for engineering puzzles. From a perspective of laboratory experiments, we summarize the common laboratory methods and provide the state-of-the-art discussions on the frictional instability of rock fractures, the permeability evolution of rock fractures, and the friction-permeability interaction on rock fractures. We particularly revisit a few published data sets to investigate the critical factors influencing the shear-induced permeability evolution of rock fractures, such as effective normal stress, shear displacement, and frictional properties. We also extend the present analytical and experimental studies to explore new insights into the friction-permeability response of rock fractures. The transition between the aseismic and seismic slip is associated not only with the changes in shear stress and fluid pressure but also with the evolution of frictional properties. The clamping and driving stresses as well as the fluid pressure develop differently in the seismic and aseismic regions near an injection point, resulting in the complexity of fracture instability.