The study of elastic properties of fractured porous rock based on digital rock

Knowledge of the elastic properties of fractured rock plays a significant role in accurate and rigorous reservoir description. In this paper, we carry out a systematic study about the effect of fracture width, fluid properties on elastic properties of reservoir rocks based on digital rock technology. Digital rock models with different fracture width are reconstructed via a superposition reconstruction procedure which impose a fracture on an isotropic host rock. A modified Finite Element Method (FEM) is adopted to investigate rock elastic properties. The results show that the presence of fracture leads to a strong anisotropy of rock. The five elastic constants of the resultant TI medium are derived as a function of the properties of the fracture width and fluid bulk modulus. The aspect ratio of P-wave velocity and S-wave velocity (V_p/V_s) is a function of fluid bulk modulus and can be used to identify fractured gas reservoir. The results allow one to have a better understanding about the correlations of fracture, fluid and elastic properties of reservoir rocks.