Model-Based Identification of the Base of the Gas Hydrate Stability Zone in Multichannel Reflection Seismic Data, Offshore Costa Rica
Date
2009-09
Authors
Gehrmann, Romina
Muller, Christian
Schikowsky, Peter
Henke, Thomas
Schnabel, Michael
Bonnemann, Christian
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Journal ISSN
Volume Title
Publisher
International Journal of Geophysics
Abstract
Along the pacific margin offshore Costa Rica the Bottom Simulating Reflector (BSR) shows a patchy occurrence in 2-D seismic reflection profiles. The reason for this can be either lack of free gas beneath parts of the gas hydrate stability zone (GHSZ) or poor seismic imaging. We compare far to near offset stacked common midpoint sections to reduce imaging ambiguity utilizing the amplitude variation with offset effect and thus successfully distinguish BSRs from regular sediment reflections. In combination with 1-D modeling of the base of the GHSZ we disqualify or qualify reflections in the predicted depth range as BSR. Additionally we calculate the heat flow and compare it with an analytical solution to detect thermal anomalies, for example, at the frontal prism. The higher confidence in BSR depths based on the far offset stacks and heat flow calculations allows further analyses on gas hydrate concentration estimates and tectonic evolution of the margin.
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Citation
Gehrmann, R., Muller, C., Schikowsky, P., Henke, T., Schnabel, M. & Bonnemann, C. (2009). Model-Based Identification of the Base of the Gas Hydrate Stability Zone in Multichannel Reflection Seismic Data, Offshore Costa Rica. International Journal of Geophysics, 2009, 12 pages. http://dx.doi.org/10.1155/2009/812713