Download or read book How Do the Gas Hydrate Saturation and Hydrate Morphology Control Seismic Attenuation written by Aoshuang Ji and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Prior studies have demonstrated a contradictory relationship between gas hydrate saturation and seismic attenuation in different regions. Yet, few studies have investigated the effect of gas hydrate morphology on seismic attenuation of gas-hydrate-bearing sediments. Here I combine seismic data with rock physics modeling to investigate how hydrate saturation and morphology influence seismic attenuation. To extract P-wave attenuation, I process both the vertical seismic profile (VSP) data within a frequency range of 30 150 Hz and sonic logging data within 10 15 kHz from three wells on the south Hydrate Ridge, offshore of Oregon, collected during Ocean Drilling Program (ODP) Leg 204 in 2000. I calculate P-wave attenuations using the spectral matching and centroid frequency shift methods, and the hydrate saturation is derived from the resistivity data above the bottom simulating reflector (BSR) at the same three wells. To interpret observed seismic attenuation in terms of the effects of both hydrate saturation and morphology, I employ a Hydrate-Bearing Effective Sediments (HBES) rock physics modeling. By comparing the observed and model-predicted attenuation values, I conclude that: (1) seismic attenuation appears to not be dominated by any single factor, instead, its variation is likely governed by both the hydrate saturation and morphology; (2) the relation between the attenuation and the hydrate saturation varies with different hydrate morphologies; (3) the gas hydrate saturation can affect its morphology by changing the growing behavior of hydrate (i.e., how hydrates accumulate in the pore space); (4) the squirt flow, occurring at different compliances of adjacent pores driven by pressure gradients, may be responsible for the significantly large or small attenuation over a broad frequency range.