Gas hydrates and free-gas trapped beneath them contain a major untapped source of energy and so are of potential economic importance. However, the elastic properties of hydrated sediments are not well-known, which leads to inaccuracy in the evaluation of the amount of gas hydrates worldwide. We reprocess multi-channel seismic line BT-1 from the Blake Ridge off the east coast of North America to obtain migrated common-angle data sets, which are then inverted for elastic impedance. New algorithms are developed and evaluated to estimate P-impedance and S-impedance from the elastic impedance. After estimating the P- and S-iumpedances, the Poisson's ratio, and Lame parameters are estimated. These elastic parameters show the presence of gas hydrates and free-gas in different ways. Calibrations, developed with the well-logs are applied to the P-impedance to estimate the water-filled porosity. The gas hydrate and free-gas saturation and concentration are estimated from the water-filled porosity with a combination of Archie's equations. The gas hydrate has as average concentration of approximately 3-5.5% by volume, and is highest (8.5%) at the base of the Gas Hydrate Stability Zone (GHSZ). The free-gas concentration ranges from 1 to 8.5% by volume, and is most developed at the topographic high.

West: -75.3245 East: -75.2807 North: 31.5035 South: 31.4708

Expedition: 164

Site: 164-994

Site: 164-995

Site: 164-997

Provider: SEDIS Publication Catalogue

Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=2003-036713 (c.f. for more detailed metadata)

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