Observed correlation between the depth to base and top of gas hydrate occurrence from review of global drilling data.

Riedel, Michael and Collett, T. S. (2017) Observed correlation between the depth to base and top of gas hydrate occurrence from review of global drilling data. Open Access Geochemistry, Geophysics, Geosystems, 18 (7). pp. 2543-2561. DOI 10.1002/2017GC006805.

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Abstract

A global inventory of data from gas hydrate drilling expeditions is used to develop relationships between the base of structure I gas hydrate stability, top of gas hydrate occurrence, sulfate-methane transition depth, pressure (water depth), and geothermal gradients. The motivation of this study is to provide first-order estimates of the top of gas hydrate occurrence and associated thickness of the gas hydrate occurrence zone for climate-change scenarios, global carbon budget analyses, or gas hydrate resource assessments. Results from publically available drilling campaigns (21 expeditions and 52 drill sites) off Cascadia, Blake Ridge, India, Korea, South China Sea, Japan, Chile, Peru, Costa Rica, Gulf of Mexico, and Borneo reveal a first-order linear relationship between the depth to the top and base of gas hydrate occurrence. The reason for these nearly linear relationships is believed to be the strong pressure and temperature dependence of methane solubility in the absence of large difference in thermal gradients between the various sites assessed. In addition, a statistically robust relationship was defined between the thickness of the gas hydrate occurrence zone and the base of gas hydrate stability (in meters below seafloor). The relationship developed is able to predict the depth of the top of gas hydrate occurrence zone using observed depths of the base of gas hydrate stability within less than 50 m at most locations examined in this study. No clear correlation of the depth to the top and base of gas hydrate occurrences with geothermal gradient and sulfate-methane transition depth was identified.

Document Type: Article
Keywords: gas hydrate; drilling expeditions; IODP
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1002/2017GC006805
ISSN: 1525-2027
Projects: IODP, ODP, DSDP
Date Deposited: 02 Aug 2017 11:46
Last Modified: 01 Feb 2019 15:00
URI: http://oceanrep.geomar.de/id/eprint/39004

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