The study of the mesoscopic attenuation phenomena in stratified or
heterogeneous rocks is an important problem in the fields of theoretical
and numerical rock physics. In this work we present a finite element
procedure based on Biot's equations to estimate the effective phase
velocity and mesoscopic attenuation in patchy saturated porous rocks.
The method also involves a Montecarlo approach and the use of stochastic
fractals to generate different saturation patterns within the porous
sample. We perform a statistical analysis of the results for irregular
patches of gas and water for different overall saturations in the
seismic range. This allows us to conclude that phase velocities and
mesoscopic attenuation are magnitudes very sensitive to the overall
saturation of the rock. In particular, this attenuation mechanism
may cause strong attenuation of seismic signals in reservoir rocks.