Fine-scale gas distribution in marine sediments assessed from deep-towed seismic data

Abstract : In the context of seismic imaging of gas/gas-hydrate systems, the fine-scale structure of subseabed gas-related reflections is assessed by taking advantage of the source signature of the deep-towed high-resolution SYSIF seismic device. We demonstrate the value of an original wavelet-based method and associated multiscale seismic attributes, applied to seismic data recently acquired on the western margin of the Arctic archipelago of Svalbard. From analysis in the wavelet domain, we recognize two types of gas-related reflections associated with submetre-scale distribution of gas. We identify a thin gas-charged layer associated with an apparent normal polarity reflection, and we detect gas patches associated with a reversepolarity bright spot with frequency-dependent elastic properties at small seismic wavelengths. The results provide valuable information on the scale of features through which gas migrates and resolve ambiguities in the interpretation of the seismic data.