Fractures are ubiquitous in the brittle lithosphere in the upper part of earth’s crust. They play a critical role in the transport of fluids. Moreover, all major discovered geothermal reservoirs and a considerable number of petroleum reservoirs are in fractured rocks. This restates the importance of studying multiphase flow behavior inside the opened fracture space. From the engineering point of view, a rock fracture as defined here is simply a complex-shaped cavity filled with fluids or solid minerals. Therefore it is understood to include cracks, joints, and faults. Fractures are formed by a crystallized melt and/or mechanical failure of the rock due to regional or local geological stresses.
