This paper studies the energy conversions that take place at discontinuities
within gas hydrate-bearing sediments and their influence on the attenuation
of waves traveling through these media. The analysis is based on
a theory recently developed by some of the authors, to describe wave
propagation in multiphasic porous media composed of two solids saturated
by a single-phase fluid. Real data from the Mallik 5L-38 Gas Hydrate
Research well are used to calibrate the physical model, allowing
to obtain information about the characteristics of the cementation
between the mineral grains and gas hydrates for this well. Numerical
experiments show that, besides energy conversions to reflected and
transmitted classical waves, significant fractions of the energy
of propagating waves may be converted into slow-waves energy at plane
heterogeneities within hydrated sediments. Moreover, numerical simulations
of wave propagation show that very high levels of attenuation can
take place in the presence of heterogeneous media composed of zones
with low and high gas hydrate saturations with sizes smaller or on
the order of the wavelengths of the fast waves at sonic frequencies.
These attenuation levels are in very good agreement with those measured
at the Mallik 5L-38 Gas Hydrate Research Well, suggesting that these
scattering-type effects may be a key-parameter to understand the
high sonic attenuation observed at gas hydrate-bearing sediments.