Fluids and frequency dependent seismic velocity of rocks

Compressional and shear velocities of rocks are dependent on frequency and this dispersion may be significant even within the seismic band. The amount and position of dispersion will be largely a function of fluid properties, distribution, and motion in the pores. Velocities are thus directly coupled to rock permeability and pore compliance. Propagation often will be in the high frequency regime, even at a few tens of Hertz. Static, or low frequency models such as Gasmann will fail under such conditions. In addition, Biot theory will not correctly model wave propagation in many cases.