Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence
Identifying gas hydrates in the oceanic subsurface using seismic reflection data supported by the presence of a bottom simulating reflector (BSR) is not an easy task, given the wide range of geophysical methods that have been applied to do so. Though the presence of the BSR is attributed to the atte...
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MDPI AG
2021-10-01
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| Online Access: | https://www.mdpi.com/2076-3263/11/11/450 |
| _version_ | 1797510173039788032 |
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| author | Roberto Clairmont Heather Bedle Kurt Marfurt Yichuan Wang |
| author_facet | Roberto Clairmont Heather Bedle Kurt Marfurt Yichuan Wang |
| author_sort | Roberto Clairmont |
| collection | DOAJ |
| description | Identifying gas hydrates in the oceanic subsurface using seismic reflection data supported by the presence of a bottom simulating reflector (BSR) is not an easy task, given the wide range of geophysical methods that have been applied to do so. Though the presence of the BSR is attributed to the attenuation response, as seismic waves transition from hydrate-filled sediment within the gas hydrate stability zone (GHSZ) to free gas-bearing sediment below, few studies have applied a direct attenuation measurement. To improve the detection of gas hydrates and associated features, including the BSR and free gas accumulation beneath the gas hydrates, we apply a recently developed method known as Sparse-Spike Decomposition (SSD) that directly measures attenuation from estimating the quality factor (Q) parameter. In addition to performing attribute analyses using frequency attributes and a spectral decomposition method to improve BSR imaging, using a comprehensive analysis of the three methods, we make several key observations. These include the following: (1) low-frequency shadow zones seem to correlate with large values of attenuation; (2) there is a strong relationship between the amplitude strength of the BSR and the increase of the attenuation response; (3) the resulting interpretation of migration pathways of the free gas using the direct attenuation measurement method; and (4) for the data analyzed, the gas hydrates themselves do not give rise to either impedance or attenuation anomalies that fully differentiate them from nearby non-hydrate zones. From this last observation, we find that, although the SSD method may not directly detect in situ gas hydrates, the same gas hydrates often form an effective seal trapping and deeper free gas accumulation, which can exhibit a large attenuation response, allowing us to infer the likely presence of the overlying hydrates themselves. |
| first_indexed | 2024-03-10T05:27:51Z |
| format | Article |
| id | doaj.art-b1301b05df124ecf96dcac5cf5ddcbd5 |
| institution | Directory Open Access Journal |
| issn | 2076-3263 |
| language | English |
| last_indexed | 2024-03-10T05:27:51Z |
| publishDate | 2021-10-01 |
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| series | Geosciences |
| spelling | doaj.art-b1301b05df124ecf96dcac5cf5ddcbd52023-11-22T23:29:52ZengMDPI AGGeosciences2076-32632021-10-01111145010.3390/geosciences11110450Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate PresenceRoberto Clairmont0Heather Bedle1Kurt Marfurt2Yichuan Wang3School of Geosciences, University of Oklahoma, 100 East Boyd Street, RM 710, Norman, OK 73019, USASchool of Geosciences, University of Oklahoma, 100 East Boyd Street, RM 710, Norman, OK 73019, USASchool of Geosciences, University of Oklahoma, 100 East Boyd Street, RM 710, Norman, OK 73019, USADepartment of Geoscience, University of Calgary, Calgary, AB T2N 1N4, CanadaIdentifying gas hydrates in the oceanic subsurface using seismic reflection data supported by the presence of a bottom simulating reflector (BSR) is not an easy task, given the wide range of geophysical methods that have been applied to do so. Though the presence of the BSR is attributed to the attenuation response, as seismic waves transition from hydrate-filled sediment within the gas hydrate stability zone (GHSZ) to free gas-bearing sediment below, few studies have applied a direct attenuation measurement. To improve the detection of gas hydrates and associated features, including the BSR and free gas accumulation beneath the gas hydrates, we apply a recently developed method known as Sparse-Spike Decomposition (SSD) that directly measures attenuation from estimating the quality factor (Q) parameter. In addition to performing attribute analyses using frequency attributes and a spectral decomposition method to improve BSR imaging, using a comprehensive analysis of the three methods, we make several key observations. These include the following: (1) low-frequency shadow zones seem to correlate with large values of attenuation; (2) there is a strong relationship between the amplitude strength of the BSR and the increase of the attenuation response; (3) the resulting interpretation of migration pathways of the free gas using the direct attenuation measurement method; and (4) for the data analyzed, the gas hydrates themselves do not give rise to either impedance or attenuation anomalies that fully differentiate them from nearby non-hydrate zones. From this last observation, we find that, although the SSD method may not directly detect in situ gas hydrates, the same gas hydrates often form an effective seal trapping and deeper free gas accumulation, which can exhibit a large attenuation response, allowing us to infer the likely presence of the overlying hydrates themselves.https://www.mdpi.com/2076-3263/11/11/450gas hydratesattenuationquality factorattributesspectral decomposition |
| spellingShingle | Roberto Clairmont Heather Bedle Kurt Marfurt Yichuan Wang Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence Geosciences gas hydrates attenuation quality factor attributes spectral decomposition |
| title | Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence |
| title_full | Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence |
| title_fullStr | Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence |
| title_full_unstemmed | Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence |
| title_short | Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence |
| title_sort | seismic attribute analyses and attenuation applications for detecting gas hydrate presence |
| topic | gas hydrates attenuation quality factor attributes spectral decomposition |
| url | https://www.mdpi.com/2076-3263/11/11/450 |
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