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→Gas destruction
==Gas destruction==
==Gas destruction==
Methane is the most thermodynamically stable hydrocarbon in sedimentary basins.<ref name=ch11r16>Hunt, J., M., 1979, Petroleum Geochemistry and Geology: San Francisco, W., H. Freeman, 617 p.</ref> Methane apparently can be destroyed only by oxidation. The most common form of oxidation in the burial environment is thermogenic sulfate reduction.<ref name=ch11r20>Krouse, H., R., 1979, Stable isotope geochemistry of non-hydrocarbon constituents of natural gas: Proceedings of the Tenth World Petroleum Congress, vol. 4, p. 85–91.</ref> The presence of oxidized iron can also remove methane at high temperatures.
Methane is the most thermodynamically stable hydrocarbon in sedimentary basins.<ref name=ch11r16>Hunt, J. M., 1979, Petroleum Geochemistry and Geology: San Francisco, W. H. Freeman, 617 p.</ref> Methane apparently can be destroyed only by oxidation. The most common form of oxidation in the burial environment is thermogenic sulfate reduction.<ref name=ch11r20>Krouse, H. R., 1979, Stable isotope geochemistry of non-hydrocarbon constituents of natural gas: Proceedings of the Tenth World Petroleum Congress, vol. 4, p. 85–91.</ref> The presence of oxidized iron can also remove methane at high temperatures.
Studies by Barker and Takach.<ref name=ch11r2>Barker, C., Takach, N., E., 1992, [http://archives.datapages.com/data/bulletns/1992-93/data/pg/0076/0012/0000/1859.htm Prediction of natural gas composition in ultradeep sandstone reservoirs]: AAPG Bulletin, vol. 76, p. 1859–1873.</ref> indicate water can oxidize methane to carbon dioxide and hydrogen gas at temperatures as low as [[temperature::200°C]], assuming systems are at thermo-dynamic equilibrium. Where oxygen fugacity is buffered at modestly reducing conditions, methane is calculated to remain stable to temperatures > [[temperature::400°C]]<ref name=ch11r10>Green, D., H., Falloon, T., J., Taylor, W., R., 1987, Mantle-derived magmas—roles of variable source peridotite and variable C-H-O fluid compositions, in Mysen, B. O., ed., Magmatic Processes: Physiochemical Principles: The Geochemical Society Special Publication No. 1, p. 139–153.</ref>
Studies by Barker and Takach.<ref name=ch11r2>Barker, C., and N. E. Takach, 1992, [http://archives.datapages.com/data/bulletns/1992-93/data/pg/0076/0012/0000/1859.htm Prediction of natural gas composition in ultradeep sandstone reservoirs]: AAPG Bulletin, vol. 76, p. 1859–1873.</ref> indicate water can oxidize methane to carbon dioxide and hydrogen gas at temperatures as low as [[temperature::200°C]], assuming systems are at thermo-dynamic equilibrium. Where oxygen fugacity is buffered at modestly reducing conditions, methane is calculated to remain stable to temperatures > [[temperature::400°C]]<ref name=ch11r10>Green, D. H., T. J. Falloon, and W. R. Taylor, 1987, Mantle-derived magmas—roles of variable source peridotite and variable C-H-O fluid compositions, in Mysen, B. O., ed., Magmatic Processes: Physiochemical Principles: The Geochemical Society Special Publication No. 1, p. 139–153.</ref>
==Predicting gas destruction==
==Predicting gas destruction==