Amplitude blanking related to the pore-filling of gas hydrate in sediments

摘要

Seismic indicators of gas-hydrate-bearing sediments include elevated interval velocities and amplitude reduction of seismic reflections owing to the presence of gas hydrate in the sediment's pore spaces. However, large amplitude blanking with relatively low interval velocities observed at the Blake Ridge has been enigmatic because realistic seismic models were absent to explain the observation. This study proposes models in which the gas hydrate concentrations vary in proportion to the porosity. Where gas hydrate concentrations are greater in more porous media, a significant amplitude blanking can be achieved with relatively low interval velocity. Depending on the amount of gas hydrate concentration in the pore space, reflection amplitudes from hydrate-bearing sediments can be much less, less or greater than those from corresponding non-hydrate-bearing sediments.