An effective anisotropic poroelastic model for elastic wave propagation in finely layered media

摘要

Mesoscopic-scale heterogeneities in porous media cause attenuation and dispersion at seismic frequencies. Effective models are often used to account for this. We have developed a new effective poroelastic model for finely layered media, and we evaluated its impact focusing on the angledependent attenuation behavior. To enable this, an exact solution was obtained for the response of a periodically layered medium to a surface point load using Floquet’s theory. We compared this solution with that of the new model and the equivalent viscoelastic vertical transverse isotropic medium available from existing literature. We have observed that the quasi-P (qP) wave dispersion and attenuation was predicted with high accuracy by the new effective poroelastic model. For the quasi-S (qS) wave, the effective poroelastic model provides a perceptibly better prediction of the attenuation, resulting in closer to the exact waveforms. The qS-wave attenuation is underestimated by the effective viscoelastic model, whereas for the qP-wave, the model gives accurate predictions in all cases except for highly permeable weakframe media.