Seismic anisotropy in gas-hydrate- and gas-bearing sediments on the Blake Ridge, from a walkaway vertical seismic profile
Geophysical Research Letters
By: I.A. Pecher, W.S. Holbrook, M.K. Sen, D. Lizarralde, W.T. Wood, D. R. Hutchinson, William P. Dillon, H. Hoskins, and R.A. Stephen
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Abstract
We present results from an analysis of anisotropy in marine sediments using walkaway vertical seismic profiles from the Blake Ridge, offshore South Carolina. We encountered transverse isotropy (TI) with a vertical symmetry axis in a gas-hydrate-bearing unit of clay and claystone with Thomsen parameters ?? = 0.05 ?? 0.02 and ?? = 0.04 ?? 0.06. TI increased to ?? = 0.16 ?? 0.04 and ?? = 0.19 ?? 0.12 in the underlying gas zone. Rock physics modeling suggests that the observed TI is caused by a partial alignment of clay particles rather than high-velocity gas-hydrate veins. Similarly, the increase of TI in the gas zone is not caused by thin low-velocity gas layers but rather, we speculate, by the sharp contrast between seismic properties of an anisotropic sediment frame and elongated gas-bearing pore voids. Our results underscore the significance of anisotropy for integrating near-vertical and wide-angle seismic data.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Seismic anisotropy in gas-hydrate- and gas-bearing sediments on the Blake Ridge, from a walkaway vertical seismic profile |
| Series title | Geophysical Research Letters |
| Volume | 30 |
| Issue | 14 |
| Year Published | 2003 |
| Language | English |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Geophysical Research Letters |
| Google Analytic Metrics | Metrics page |