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Updated: Aug 9, 2026

Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample
Published on: March 21, 2016
Thermodynamic calculations in the system CH4-H2O and methane hydrate phase equilibria
Susan Circone1, Stephen H Kirby, Laura A Stern
1U.S. Geological Survey, 345 Middlefield Rd. MS 977, Menlo Park, California 94025, USA.
Abstract:
Using the Gibbs function of reaction, equilibrium pressure, temperature conditions for the formation of methane clathrate hydrate have been calculated from the thermodynamic properties of phases in the system CH4-H2O. The thermodynamic model accurately reproduces the published phase-equilibria data to within +/-2 K of the observed equilibrium boundaries in the range 0.08-117 MPa and 190-307 K. The model also provides an estimate of the third-law entropy of methane hydrate at 273.15 K, 0.1 MPa of 56.2 J mol(-1) K(-1) for 1/nCH4.H2O, where n is the hydrate number. Agreement between the calculated and published phase-equilibria data is optimized when the hydrate composition is fixed and independent of the pressure and temperature for the conditions modeled.
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