Measurements of acoustic wave velocities and attenuation in marine sediments

Propagation and attenuation of acoustic waves in fluid-saturated sediments have been studied theoretically and experimentally. In situ acoustic transmission tests in saturated beach sand show that compressional waves are dispersive within a certain frequency band where the intrinsic attenuation is maximum. This indicates that low-frequency wave velocities in marine sediments are at least 5% to 10% less than the velocities obtained from high-frequency measurements, and viscous damping, due to the relative motion between solid skeleton and fluid, is the main damping mechanism in the frequency range of 1–30 kHz. The agreement between the experimental results and Biot’s theory enables the remote determination of porosity and permeability of marine sediments by using measured compressional and shear wave characteristics. Approximate relations are used to determine the porosity and permeability of the marine sediments using the measured acoustic wave velocities and attenuation.