Ehsan Khamehchi - Amirkabir University Of Technology , Department of petroleum Engineering
Ebrahim Shamohammadi - Amirkabir University Of Technology , Department of petroleum Engineering

Gas hydrates (gas clathrates) are solid compounds of natural gas molecules that are encaged within a crystal structure composed of water molecules. Hydrates can form anywhere and anytime that hydrocarbons and water are present at low temperatures and high pressures (Sloan,1999). The formation of gas hydrates during hydrocarbon production and transportation is a serious problem in the petroleum industry.Typical hydrate-forming guests include CH4, C2H6, C3H8, i-C4H10, CO2, H2S, CHCL3 and the noble gases. (Sloan,1998)Gas hydrate formation is a concomitant process requiring the presence of both the host and guest molecular species. Conditions under which hydrates will form are determined largely by the nature of the guest, but for most common compounds of natural gas they will crystallize at temperatures above the ice point with pressures nearly 10 atm. Such conditions are also common in oil and gas transmission, and so gas hydrate formation is a major potential cause of pipeline occlusion. The existence of clathrate hydrate was first documented by Sir Humphery Davy in 1810, who observed that a solution of chlorine gas in water freezes more readily than pure water. Since 1934, when Hummerschmidt concluded that natural gas hydrates were blocking gas transmission lines, the susceptibility of forming solid hydrates in gas transmission under normal operating conditions has led to many investigations aimed at understanding and avoiding hydrate formation, an area of ongoing research (Sloan,1998).