Gas Hydrates in Ocean Bottom Sediments

AAPG Bulletin ◽  
1982 ◽  
Vol 66 ◽  
Author(s):  
M. K. MacLeod (2)
Keyword(s):  
Bottom Sediments ◽  
Gas Hydrates ◽  
Ocean Bottom

A Broad-Band Study of Attenuation in Ocean Bottom Sediments

1986 ◽  
pp. 609-621 ◽  
Author(s):  
Jeffrey S. Barker ◽  
Donald V. Helmberger
Keyword(s):  
Bottom Sediments ◽  
Broad Band ◽  
Ocean Bottom

scholarly journals Postglacial response of Arctic Ocean gas hydrates to climatic amelioration

2017 ◽  
Vol 114 (24) ◽  
pp. 6215-6220 ◽  
Author(s):  
Pavel Serov ◽  
Sunil Vadakkepuliyambatta ◽  
Jürgen Mienert ◽  
Henry Patton ◽  
Alexey Portnov ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Gas Hydrates ◽  
Gas Hydrate ◽  
Bottom Water ◽  
Environmental Changes ◽  
Thermal Dissociation ◽  
Ice Sheet ◽  
The Arctic ◽  
Ocean Bottom ◽  
Methane Release

Seafloor methane release due to the thermal dissociation of gas hydrates is pervasive across the continental margins of the Arctic Ocean. Furthermore, there is increasing awareness that shallow hydrate-related methane seeps have appeared due to enhanced warming of Arctic Ocean bottom water during the last century. Although it has been argued that a gas hydrate gun could trigger abrupt climate change, the processes and rates of subsurface/atmospheric natural gas exchange remain uncertain. Here we investigate the dynamics between gas hydrate stability and environmental changes from the height of the last glaciation through to the present day. Using geophysical observations from offshore Svalbard to constrain a coupled ice sheet/gas hydrate model, we identify distinct phases of subglacial methane sequestration and subsequent release on ice sheet retreat that led to the formation of a suite of seafloor domes. Reconstructing the evolution of this dome field, we find that incursions of warm Atlantic bottom water forced rapid gas hydrate dissociation and enhanced methane emissions during the penultimate Heinrich event, the Bølling and Allerød interstadials, and the Holocene optimum. Our results highlight the complex interplay between the cryosphere, geosphere, and atmosphere over the last 30,000 y that led to extensive changes in subseafloor carbon storage that forced distinct episodes of methane release due to natural climate variability well before recent anthropogenic warming.

IDENTIFICATION OF GAS HYDRATES AND BOTTOM SIMULATING REFLECTORS IN FAR OFFSET SEISMIC IMAGES

2021 ◽  
pp. 1-60
Author(s):  
Darrell A. Terry ◽  
Camelia C. Knapp
Keyword(s):  
Gas Hydrates ◽  
Seismic Data ◽  
Single Channel ◽  
Seismic Analysis ◽  
Cost Effective ◽  
Ocean Bottom ◽  
Bottom Simulating Reflector ◽  
Avo Analysis ◽  
Bottom Simulating Reflectors ◽  
Seismic Images

The presence of marine gas hydrates is routinely inferred based on the identification of bottom simulating reflectors (BSRs) in common depth-point (CDP) seismic images. Additional seismic studies such as amplitude variation with offset (AVO) analysis can be applied for corroboration. Though confirmation is needed by drilling and sampling, seismic analysis has proven to be a cost-effective approach to identify the presence of marine gas hydrates. Single channel far offset seismic images are investigated for what appears to be a more reliable and cost-effective indicator for the presence of bottom simulating reflectors than traditional CDP processing or AVO analysis. A non-traditional approach to processing seismic data is taken to be more relevant to imaging the gas/gas hydrate contact. Instead of applying the traditional CDP seismic processing workflows from the oil industry, we more carefully review the significant amount of information existing in the data to explore how the character of the data changes as offset angle increases. Three cases from different environments are selected for detailed analysis. These include 1) stratigraphy running parallel with the ocean bottom; 2) a potential bottom simulating reflector, running parallel to the ocean bottom, and cross-cutting dipping reflections, and 3) a suspected thermal intrusion without a recognizable bottom simulating reflector. This investigation considers recently collected multi-channel seismic data from the deep waters of the central Aleutian Basin beneath the Bering Sea, the pre-processing of the data sets, and the methodology for processing and display to generate single channel seismic images. Descriptions are provided for the single channel near and far offset seismic images for the example cases. Results indicate that BSRs related to marine gas hydrates, and originating due to the presence of free gas, are more easily and uniquely identifiable from single channel displays of far offset seismic images than from traditional CDP displays.

A geothermal method for detecting gas hydrates in the bottom sediments of water basins

2012 ◽  
Vol 53 (7) ◽  
pp. 704-711 ◽  
Author(s):  
A.D. Duchkov ◽  
V.E. Istomin ◽  
L.S. Sokolova
Keyword(s):  
Bottom Sediments ◽  
Gas Hydrates

Radium content of ocean-bottom sediments

1933 ◽  
Vol s5-25 (147) ◽  
pp. 229-238 ◽  
Author(s):  
C. S. Piggot
Keyword(s):  
Bottom Sediments ◽  
Ocean Bottom ◽  
Radium Content
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