ANALYTICAL SEISMIC WAVE ATTENUATION AND VELOCITY DISPERSION IN LAYERED DOUBLE-POROSITY MEDIA

Due to differences of rock properties such as porosity, permeability and compressibility between different regions in the porous media, pressure gradients are induced between those different regions and lead to local fluid flow. When seismic wave propagates in the porous media, the local fluid flow process is a main cause of wave attenuation and velocity dispersion. The local fluid flow mechanism of the layered porous model has been studied by many authors in the numerical approaches without analytical wave equations and solution for this kind of rock physics models. In this study, we first establish a layered double-porosity model saturated with a single fluid and derive the wave equations. According to the derived novel wave equations, then we calculate the phase velocity and quality factor in the layered double-porosity media based on plane wave analysis. The results demonstrate that there are three kinds of wave modes named as the fast P-wave and two slow P-wave in layered porous media when P-wave propagates through the model perpendicularly. Finally, we study the effects of local fluid flow on the mesoscopic loss mechanism by analyzing the attenuation and the velocity dispersion of seismic waves in the low frequency range.