INFLUENCE OF FRACTURE DEFORMATION ON SECONDARY PERMEABILITY-A NUMERICAL APPROACH

Abstract In most crystalline rock masses the fracture conductivity generally exceeds the primary permeability by several orders of magnitude. Originally, discrete models for fractured media assumed the fractures to be rigid but later research has shown that fracture deformability can be an important fluid flow parameter. The present study utilizes existing models to study deformable fracture flow and attempts to define the range of influence of fracture deformation on conductivity and the limitations of the discrete approach. The model was found to be very sensitive to input data especially for dilatant shear problems. A rather straightforward coupling of dilatancy and conductivity was assumed—and this deserves further laboratory and field testing. The results indicate that dilatancy may be the most central parameter affecting conductivity in fracture flow.