Seismic attenuation and dispersion in poroelastic media with fractures of variable aperture distributions

Abstract. Considering poroelastic media containing aligned periodic fractures, we numerically quantify the effects that fractures with variable aperture distributions have on seismic wave attenuation and velocity dispersion due to fluid pressure diffusion (FPD). To achieve this, realistic models of fractures are generated with a stratified percolation algorithm which provides statistical control over geometrical fracture properties such as density and distribution of contact areas. The results are sensitive to both geometrical properties, showing that an increase in the density of contact areas as well as a decrease in their correlation length, reduce the effective seismic attenuation and the corresponding velocity dispersion. Moreover, no FPD effects are observed in addition to the one occurring between the fractures and the background, in the analysed frequency range, by considering realistic fracture models. We demonstrated that if appropriate equivalent physical properties accounting for the effects of contact areas are employed, a simple planar fracture can be used to emulate the seismic response of fractures with realistic aperture distributions. The excellent agreement between their seismic responses is demonstrated for all incidence angles and wave modes.