Abstract

Seismic attenuation is not due entirely to intrinsic properties; a component due to scattering effects is included. Although different techniques have been used to experimentally investigate the attenuation of seismic waves, not so many laboratory measurements of attenuation have taken into account the effect of scattering attenuation. Herein, partially frozen brine as a solid-liquid coexistence system is used to investigate attenuation phenomena. We obtained a series of 2D apparent diffusion coefficient (ADC) maps of the ice-brine coexisting system using a diffusion-weighted magnetic resonance imaging (DW-MRI) technique at 5°C, and found a strongly heterogeneous spatial distribution of unfrozen brine. From these maps, we constructed a synthetic seismic data set propagating through 2D media, and generated synthetic data with a second-order finite-difference scheme for the 2D acoustic wave equation. We estimated ultrasonic scattering attenuation in such systems by the centroid frequency shift method and by assuming that the quality factor (Q-value) is independent of frequency. The estimated scattering attenuation ranges from 0.015 to 0.05, corresponding to 10% to 30% of the total attenuation measured in laboratory experiments.

You do not currently have access to this article.