Formation mechanism and prevention of gas hydrate

Formation mechanism and prevention of gas hydrate

2013-03-27 21:00:08

Natural gas hydrate is composed of water and gas molecules in the low temperature, high pressure through intermolecular forces (hydrogen bonding) cage type solid mixture formation, in snow and ice shape. In gas hydrates, water molecules of a lattice structure containing cavities formed by hydrogen bonding interaction. When the gas hydrate lattice and the hole in the presence of no guest molecules, the hydrates are unstable.
Due to lattice cavity size limit, cavity has selectivity to molecules of a gas, the gas molecules is too young not to support the cage effect (not form a stable hydrate), but for hydrocarbon pentane above, because the material molecular size is too large, can not enter the cavity forming crystal frame fixed, generally will not generate hydrate. Only when the gas hydrate lattice and the hole in the gas molecules occupy the most is, to form the gas hydrate stability. The formation of natural gas hydrate mainly has 3 conditions:
(1) to have the liquid water existence or natural gas and water is supersaturated in natural gas.
(2) a sufficiently high pressure and a low enough temperature.
(3) must have the auxiliary conditions, such as pressure, gas flow fluctuation of mutation of agitation and nuclear presence.
From the above analysis of the causes of formation of hydrates, which can be summed up usually measures to prevent hydrate formation:
(1) reduce the work pressure of gas well.
(2) adding hydrate inhibitor.
(3) natural gas heating.
(4) natural gas dehydration.