The study of reservoir and repository performance requires the integration of many different fields in Earth sciences, among them rock physics and geomechanics. The aim of this book is to emphasize how rock physics and geomechanics help to get a better insight into important issues linked to reservoir management for exploitation of natural resources, and to repository safety assessment for hazardous waste storage in geological environment. The studies presented here deal with the hydromechanical coupling in fractured rocks, the key experiments in safety assessment of repositories, the development of damaged zones during excavation in a shaley formation, the influence of temperature on the properties of shales, the poroelastic response of sandstones, the development and propagation of compaction bands in reservoir rocks, imaging techniques of geomaterials, the characterization and modelling of reservoirs using 4D seismic data, the mechanical behaviour of fractured rock masses, the petrophysical properties of fault zones, models for rock deformation by pressure solution and the elastic anisotropy in cracked rocks.