Poroelastic analysis of permeability effects in thinly layered porous media

The mechanism of wave-induced fluid flow, which causes significant attenuation and dispersion of seismic waves in heterogeneous porous media, opens a potential opportunity to estimate fluid-mobility properties from seismic data. However, the permeability effects on seismic data vary for different reservoir environments, so rules of thumb are difficult to establish. Two types of reservoir models were selected. One represents shallow, unconsolidated, low-impedance reservoirs. The other represents deep, consolidated, high-impedance reservoirs. Using analytic equations and wave-propagation numerical studies, permeability effects were investigated on the magnitude and phase of normal-incident reflection coefficients from an interface between an upper nondispersive medium and a lower thinly layered porous medium. The study found that permeability can affect reflection amplitudes significantly. For high-impedance reservoirs, magnitude of the reflection coefficient decreases when permeability increases. However, for low-impedance reservoirs, reflection magnitude increases as permeability increases.