Seismic Attenuation in Porous Rocks Containing Random Distributions of Aligned Fractures

In this work, we present a numerical methodology for computing seismic attenuation and velocity dispersion due to wave-induced fluid flow for P-waves propagating perpendicular to a set of parallel planar fractures. The approach allows us to consider a large number of irregularly distributed fractures and characterized by variable apertures. We perform Monte Carlo simulations to explore the effects of the geometrical characteristics of the fracture distributions and of their apertures on the effective seismic properties. The results show that regular and random fracture distributions exhibit different P-wave attenuation behaviors. The larger the range of background lengths involved in the sample, the flatter the attenuation curve and the larger the discrepancies in the asymptotic behavior at low frequencies with respect to regular distributions of fractures. For samples with regular distributions of fractures, those with randomly varying apertures exhibit a different scaling of the attenuation curve at low frequencies compared to a periodic distribution of fracture apertures. In both cases, the frequency of the attenuation peak remains the same as the background thickness does not change.