Seismic AVO analysis of methane hydrate structures
- Stanford Univ., CA (United States)
Marine seismic data from the Blake Outer Ridge offshore Florida show strong bottom simulating reflections (BSRs) associated with methane hydrate occurrence in deep marine sediments. The authors use a detailed amplitude versus offset (AVO) analysis of these data to explore the validity of models which might explain the origin of bottom simulating reflectors. After careful preprocessing steps including source wavelet deconvolution, nonlinear cable trace interpolation, amplitude and moveout traveltime calibration, and velocity analysis, they determine a BSR model which can successfully reproduce the observed AVO responses. The P- and S-velocity behavior predicted by the forward modeling approach is further investigated by estimating the P- and S-impedance contrasts at all subsurface positions. This is done by applying a least-squares elastic parameter inversion method to the preprocessed CMP gathers. Their results state that the Blake Outer Ridge BSR is compatible with a model of methane hydrate in sediment, overlaying a layer of free methane gas-saturated sediment, and is not consistent with a model of hydrate overlaying brine-saturated sediment. A thickness of approximately 250 meters is inferred from the modeling.
- OSTI ID:
- 89714
- Report Number(s):
- CONF-941015--
- Country of Publication:
- United States
- Language:
- English
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