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Detecting subsea permafrost layers on marine seismic data: An appraisal from forward modeling

Mathieu J. Duchesne, Gabriel Fabien-Ouellet and Jefferson Bustamante

Article (2023)

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Abstract

Detecting the top and base subsea permafrost from 2D seismic reflection data in shallow marine settings is a non-trivial task due to the occurrence of strong free surface multiples. The potential to accurately detect permafrost layers on conventional 2D seismic reflection data is assessed through viscoelastic modelling. Reflection imaging of permafrost layers is examined through the evaluation of specific characteristics of the subsurface, acquisition parameters and their impact. Results show that limitations are related to the principles of the method, the intrinsic nature of the permafrost layers, and the acquisition geometry. The biggest challenge is the occurrence of free surface multiples that overprint the base permafrost reflection, with the worst-case scenario the case of a thin layer of ice-bonded sand. Wedge models suggest that if the base permafrost is dipping, it would intersect internal and free surface multiples of the seafloor and the top permafrost and be detected. Also, the amplitude ratio of the base permafrost reflection and the multiples decreases with the increasing thickness of permafrost. Therefore, the crosscutting relationship between the reflection at base permafrost reflection and the multiples might not be enough to detect the base permafrost for thicker permafrost layers. Finally, the experiment results show that, for partially ice-bonded layers, the attenuation combined with the low reflectivity of the basal interface limits the likelihood to resolve the base permafrost, especially for thick permafrost layers.

Uncontrolled Keywords

2D; modelling; reflection; seismic; shallow marine

Department: Department of Civil, Geological and Mining Engineering
Funders: Geological Survey of Canada
Grant number: 20210458
PolyPublie URL: https://publications.polymtl.ca/51362/
Journal Title: Near Surface Geophysics (vol. 21, no. 1)
Publisher: Wiley
DOI: 10.1002/nsg.12231
Official URL: https://doi.org/10.1002/nsg.12231
Date Deposited: 18 Apr 2023 14:58
Last Modified: 05 Apr 2024 11:55
Cite in APA 7: Duchesne, M. J., Fabien-Ouellet, G., & Bustamante, J. (2023). Detecting subsea permafrost layers on marine seismic data: An appraisal from forward modeling. Near Surface Geophysics, 21(1), 3-20. https://doi.org/10.1002/nsg.12231

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