| Abstract: | Introduction
Gas hydrates are crystalline solids in which molecules of a ‘guest‘ species occupy and stabilize cages formed by water molecules. Similar to ice in appearance (fig. 1), gas hydrates are stable at high pressures and temperatures above freezing (0?C). Methane is the most common naturally occurring hydrate guest species. Methane hydrates, also called simply ‘gas hydrates,‘ are extremely concentrated stores of methane and are found in shallow permafrost and continental margin sediments worldwide. Brought to sea-level conditions, methane hydrate breaks down and releases up to 160 times its own volume in methane gas.
The methane stored in gas hydrates is of interest and concern to policy makers as a potential alternative energy resource and as a potent greenhouse gas that could be released from sediments to the atmosphere and ocean during global warming. In continental margin settings, methane release from gas hydrates also is a potential geohazard and could cause submarine landslides that endanger offshore infrastructure.
Gas hydrate stability is sensitive to temperature changes. To understand methane release from gas hydrate, the U.S. Geological Survey (USGS) conducted a laboratory investigation of pure methane hydrate thermal properties at conditions relevant to accumulations of naturally occurring methane hydrate. Prior to this work, thermal properties for gas hydrates generally were measured on analog systems such as ice and non-methane hydrates or at temperatures below freezing; these conditions limit direct comparisons to methane hydrates in marine and permafrost sediment.
Three thermal properties, defined succinctly by Briaud and Chaouch (1997), are estimated from the experiments described here:
* Thermal conductivity: if thermal conductivity is high, heat travels easily through the material.
* Thermal diffusivity: if thermal diffusivity is high, it takes little time for the temperature to rise in the material.
* Specific heat: if specific heat is high, it takes a great deal of heat to raise the temperature of the material. |
| Genre: | USGS Numbered Series |
| ProdID: | 80104 |
| Citation Author: | Waite, William F. |
| Citation Contributing Office: | USGS Woods Hole Science Center |
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| Citation Edition: | - |
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| Citation Language: | ENGLISH |
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| Citation Month: | Jul |
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| Citation Online Only Flag: | Y |
| Citation Phsyical Description: | 2 p. |
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| Citation Publisher: | Geological Survey (U.S.) |
| Citation Series: | Fact Sheet |
| Citation Series Code: | FS |
| Citation Series Number: | 2007-3041 |
| Citation Search Results Text: | Thermal Properties of Methane Gas Hydrates; 2007; FS; 2007-3041; Waite, William F. |
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| Citation Year: | 2007 |
| Type: | citation/reference |
| Text: | Thermal Properties of Methane Gas Hydrates; 2007; FS; 2007-3041; Waite, William F. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/fs_2007_3041.jpg |
| URL (INDEX PAGE): | http://pubs.usgs.gov/fs/2007/3041/ |
| Date Other: | Wed, 18 Jul 2007 00:00 -0500 |
| Publisher: | Geological Survey (U.S.) |
