In porous fluid-saturated media, Biot's poroelasticity theory predicts a movement of the pore fluid relative to the skeleton as seismic waves propagate through the reservoir. This phenomenon opens an opportunity for investigation of the flow properties of the hydrocarbon-saturated reservoirs. Dependence of seismic amplitudes on permeability was discussed by Pride et al. (2003). A recently published paper (Kozlov, 2007), shows the seismic signature for a permeable-layered medium. It is well known that relative fluid movement becomes negligible at seismic frequencies if the porous material is homogeneous and well cemented. In this case, Biot's theory predicts seismic wave velocity dispersion and attenuation that are lower than measured. Using numerical Biot model experiments, Helle et al. (2003) demonstrated substantial effects on both velocity and attenuation due to heterogeneities in either permeability or fluid saturation. In addition to fluid-flow effects, scattering plays a very important role in finely layered porous rocks and with heterogeneous fluid saturation (Gurevich et al., 1997). We use both fluid flow and scattering mechanisms to derive a frequency-dependent seismic attribute which is proportional to fluid mobility and use it to estimate reservoir permeability.