Changes

Gas hydrates have been commonly mentioned as potentially vast sources of [[natural gas]]. The high cost and the technical, operational, and environmental problems of recovering gas from these reservoirs make them unlikely sources of gas for many years to come, certainly as long as cheaper, more readily produced sources of gas are available.

Gas hydrates have been commonly mentioned as potentially vast sources of [[natural gas]]. The high cost and the technical, operational, and environmental problems of recovering gas from these reservoirs make them unlikely sources of gas for many years to come, certainly as long as cheaper, more readily produced sources of gas are available.

Gas hydrates (also called gas clathrates) are icelike, crystalline solids composed of natural-gas molecules, principally [[methane]], trapped in rigid crystalline cages formed by frozen water molecules. They are known to be stable under conditions of high pressure and low temperature that have been recognized in polar regions at depths from 130 to 2000 m (425 to 6500 ft), where temperatures are low enough for the formation of [[permafrost]], and in the uppermost part of deep-water sediments below the sea floor at depths of more than 100-1100 m (330-3600 ft).<ref name=Collett_2001>Collett, T. S., 2001, [http://archives.datapages.com/data/specpubs/memoir74/m74ch07/m74ch07.htm Natural-gas hydrates: Resources of the twenty-first century?], ''in'' M. W. Downey et al., eds., Petroleum provinces of the twenty-first century: AAPG Memoir 74, p. 85-108.</ref><ref name=Collett_2002>Collett, T. S., 2002, [http://archives.datapages.com/data/specpubs/memoir74/m74ch07/m74ch07.htm Energy resource potential of natural gas hydrates]: AAPG Bulletin, v. 86, no. 11, p. 1971-1992.</ref>  

Gas hydrates (also called gas clathrates) are icelike, crystalline solids composed of natural-gas molecules, principally [[methane]], trapped in rigid crystalline cages formed by frozen water molecules. They are known to be stable under conditions of high pressure and low temperature that have been recognized in polar regions at depths from 130 to 2000 m (425 to 6500 ft), where temperatures are low enough for the formation of [[permafrost]], and in the uppermost part of deep-water sediments below the sea floor at depths of more than 100-1100 m (330-3600 ft).<ref name=Collett_2001>Collett, T. S., 2001, [http://archives.datapages.com/data/specpubs/memoir74/m74ch07/m74ch07.htm Natural-gas hydrates: Resources of the twenty-first century?], ''in'' M. W. Downey et al., eds., Petroleum provinces of the twenty-first century: AAPG Memoir 74, p. 85-108.</ref><ref name=Collett_2002>Collett, T. S., 2002, [http://archives.datapages.com/data/specpubs/memoir74/m74ch07/m74ch07.htm Energy resource potential of natural gas hydrates]: AAPG Bulletin, v. 86, no. 11, p. 1971-1992.</ref>