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Gas Hydrates

Gas hydrates are crystalline water compounds in which host water compound encapsulate guest molecules like methane and carbon dioxide. They are considered as a potential source of energy in future as they are found naturally in the oceanic and permafrost regions with immense amount of methane gas entrapped in them.
It has also been proposed that carbon dioxide can be sequestered into the gas hydrates, thus reducing the carbon dioxide content in the atmosphere and extracting methane gas at the same time. They have several novel applications as hydrogen storage and transportation at significantly higher temperature and lower pressure than the conventional methods. But at the same time, they are also considered as a nuisance in the oil and gas industry as they block the pipelines. As natural gas hydrates form a solid layer extending over kilometers under the oceanic sediments, uncontrolled extraction may lead to disasters like earthquakes and tsunamis. They have a very complex structure and molecular interactions which motivates the researchers to look into them. So, gas hydrates have always been looked upon as a challenging subject of study at the industrial as well as academic level. Presently, we are trying to understand the mechanism of extraction of methane from methane hydrates, replacement of methane by carbon dioxide and formation of gas hydrates by molecular dynamics simulations.
Makogon et al., (2007) J. Petr. Sci. Eng. 56, 14–31

The extraction of methane gas hydrates involves decomposition of the methane gas hydrates. The decomposition process is known to be endothermic as it involves rearrangement of hydrogen bonded structure. Also. the pressure of the system increases as the methane gas expands into gaseous phase from the solid hydrate phase. Hence, we simulate our system under microcanonical (NVE) ensemble to observe the variations in temperature and pressure during the process.

The replacement of methane in methane gas hydrates by carbon dioxide may involve a change in structure which cannot be observed by available laboratory experimental equipments. The pressure and temperature of the system during the replacement process may vary. Hence, we are performing NVE simulations to study the replacement process.