On the Relative Importance of Global and Squirt Flow in Cracked Porous Media

In acoustic or seismic modelling, a cracked porous medium can be replaced by a long wavelength, equivalent homogenous medium that can be both anisotropic and viscoelastic due to microstructural alignments and global or squirt flow, respectively. We here investigate the relative importance of global and squirt flow in cracked porous media. We use the unified theory of global and squirt flow of Jakobsen and Chapman in cracked porous media. The investigation has been done for the implication of using the correct wave number for the relative importance of global and squirt flow in cracked porous media saturated with different fluids characterized by different viscosities and for the observations of negative velocity dispersion dealing the phenomenon of wave-induced fluid flow in models of cracked porous media where global flow effects dominates. Our numerical results suggest that the observations of negative velocity dispersion in Jakobsen and Chapman theory still remain, even if we use the correct effective wave number. The peak of attenuation always moves towards relatively lower frequencies in the case of solution with correct wave number as compared to the solution with approximate wave number for different viscosities.