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Methane clathrate (CH 4 ·5.75H 2 O) or (4CH 4 ·23H 2 O), also called methane hydrate, hydromethane, methane ice, fire ice, natural gas hydrate, or gas hydrate, is a solid clathrate compound (more specifically, a clathrate hydrate) in which a large amount of methane is trapped within a crystal structure of water, forming a solid similar to ice.
Methane clathrate block embedded in the sediment of hydrate ridge, off Oregon, USA. Clathrate hydrates, or gas hydrates, clathrates, or hydrates, are crystalline water-based solids physically resembling ice, in which small non-polar molecules (typically gases) or polar molecules with large hydrophobic moieties are trapped inside "cages" of hydrogen bonded, frozen water molecules.
Nonpolar molecules such as methane can form clathrate hydrates with water, especially under high pressure. Although there is no hydrogen bonding between water and guest molecules when methane is the guest molecule of the clathrate, guest–host hydrogen bonding often forms when the guest is a larger organic molecule such as tetrahydrofuran.
Methane clathrates feature the hydrogen-bonded framework contributed by water and the guest molecules of methane. Large amounts of methane naturally frozen in this form exist both in permafrost formations and under the ocean sea-bed. [8] Other hydrogen-bonded networks are derived from hydroquinone, urea, and thiourea.
The existence and depth of a hydrate deposit is often indicated by the presence of a bottom-simulating reflector (BSR). A BSR is a seismic reflection indicating the lower limit of hydrate stability in sediments due to the different densities of hydrate saturated sediments, normal sediments and those containing free gas. [2]
Methane clathrate, also known commonly as methane hydrate, is a form of water ice that contains a large amount of methane within its crystal structure. Potentially large deposits of methane clathrate have been found under sediments on the ocean floors of the Earth, although the estimates of total resource size given by various experts differ by ...
Because the methane hydrates are unstable, except at cool temperatures and high (deep) pressures, scientists have observed smaller outgassing events due to tectonic events. Studies suggest the huge release of natural gas [ 10 ] could be a major climatological trigger, methane itself being a greenhouse gas many times more powerful than carbon ...
In this area, the main sedimentological controls for the accumulation of gas hydrates are the sand-rich areas of the trough (Collett, 2002). Well coring indicates the presence of at least three gas hydrate zones. Krason, 1994, estimated that there are 0.42 to 4.2×10 12 cubic meters of methane within the gas hydrates. Seismically, the high ...