Propagation of pore pressure diffusion waves in saturated porous media

Abstract

A microscopic 1D analytical model was developed for describing pore pressure diffusion wave propagation in porous media. The pressure diffusion waves, being heavily damped, have relatively slow velocities and short wavelength, and do not exhibit square-law behavior. Investigation on permeability effect on attenuation dispersion and penetration depth indicates that the transition zone in attenuation and penetration depth peak shifts toward low frequency when permeability decreases. Controversially, the transition zone in phase velocity peak shifts toward high frequency when permeability decreases. The high frequency-dependent attenuation of low-frequency waves was well predicted by the pressure diffusion mechanism. At a mass interface, pressure diffusion waves obey an accumulation–depletion law, rather than the reflection–refraction law. Pressure diffusion waves are accelerated and amplified by a space-dependent diffusivity field.