Case history high-resolution, deep-towed, multichannel seismic survey of deep-sea gas hydrates off western Canada

摘要

A multichannel seismic survey was carried out us- ing the high-resolution deep-towed acoustics/geophysics system(DTAGS)to image the structure of deep-sea gas hydrates on the continental slope off Vancouver Island and to determine the velocity profile of the hydrated sediments. The high-frequency DTAGS data provide the means to estimate the frequency response of the bottom simulating reflector(BSR)that defines the base of the hydrate stability field in these sediments, over a broad frequency band from 15 to 650 Hz. The DTAGS sections resolved fine-scale layering as thin as a few meters within the hydrated zone and below the BSR, and they revealed small-scale faults and vertically oriented zones of very low acoustic reflectivity that may represent channels for upward migration of fluids or gas.