Direct measurement of methane hydrate composition along the hydrate equilibrium boundary

Journal of Physical Chemistry B
By: , and 

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Abstract

The composition of methane hydrate, namely nw for CH4·nwH2O, was directly measured along the hydrate equilibrium boundary under conditions of excess methane gas. Pressure and temperature conditions ranged from 1.9 to 9.7 MPa and 263 to 285 K. Within experimental error, there is no change in hydrate composition with increasing pressure along the equilibrium boundary, but nw may show a slight systematic decrease away from this boundary. A hydrate stoichiometry of nw = 5.81−6.10 H2O describes the entire range of measured values, with an average composition of CH4·5.99(±0.07)H2O along the equilibrium boundary. These results, consistent with previously measured values, are discussed with respect to the widely ranging values obtained by thermodynamic analysis. The relatively constant composition of methane hydrate over the geologically relevant pressure and temperature range investigated suggests that in situ methane hydrate compositions may be estimated with some confidence.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Direct measurement of methane hydrate composition along the hydrate equilibrium boundary
Series title Journal of Physical Chemistry B
DOI 10.1021/jp0504874
Volume 109
Issue 19
Year Published 2005
Language English
Publisher ACS Publications
Contributing office(s) Earthquake Science Center
Description 8 p.
First page 9468
Last page 9475
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