Attenuation Anisotropy in Fractured Media

In order to observe the effects of fractures on seismic response, a finite-difference wave equation method is developed to model wave propagation in anisotropic media, in which the elastic constants represent fractures effectively. As these elastic constants are frequency dependent, wave simulation is implemented in the frequency domain. While diffractions due to scattering of fractures can clearly identify the position of a fracture gallery, based on strong, fanlike energy mass at the high frequency spectrum, this paper focuses on the investigation of fractures with different viscosity. For viscosity, frequency dependency analyses show that low-frequency bands (<120 Hz) generally show much more variations in seismic responses than high-frequency bands. When frequency increases, the significance of viscosity is decreasing gradually. The investigation reveals that, for a plane wave with constant frequency, fracture porosity has a linear relationship with the attenuation anisotropy, and the matrix of fracture infill materials plays an important role in attenuation anisotropy.