The influence of gas saturation and pore pressure on the characteristics of the Frenkel-Biot <Emphasis Type="Italic">P</Emphasis> waves in partially saturated porous media

For the case of a partially saturated porous medium, analysis of the conditions is carried out under which the properties of the Frenkel-Biot P waves are similar. The condition of dynamic compatibility (with fulfillment of which a wave of the first kind is propagated without attenuation) is generalized to the case of partially saturated porous media. It is found that the wave connected with the matrix deformation possesses a high attenuation coefficient in a porous medium saturated with a weakly-compressible liquid, but it is a weakly decaying wave in a gas-saturated porous medium. Asymptotic formulas for phase wave velocities are obtained within a low-frequency and high-frequency limit for the general case of a partially saturated porous medium. It is shown that in the domain of low gas saturation, the attenuation coefficient of a wave of the first kind (i.e., a wave connected with the compressibility of phases) depends on the state of the gas in porous space. The following three cases are considered: (1) the microbubbles occluded in the saturating liquid; (2) the microbubbles adsorbed on the walls of pores; and (3) the macrobubbles that completely occupy one or several pores. This characteristic can be used as the diagnostic parameter.