It has long been known that crystalline hydrates are formed by many simple gases that do not interact strongly with water, and in most cases the gas molecules or atoms occupy 'cages' formed by a framework of water molecules. The majority of these gas hydrates adopt one of two cubic cage structures and are called clathrate hydrates. Notable exceptions are hydrogen and helium which form 'exotic' ...

Gas hydrates presented as form of segregated bodies have been observed on shallow subsurface sediments. However, most gas hydrate physics models describe that hydrates occur in pore space in deep subsurface sediment. A new model considers gas hydrate as segregated bodies to derive elastic properties of hydrates bearing sediments and gas hydrate saturation. The predicted elastic properties based...

The Michelsen stability and multiphase flash calculation by direct minimization of Gibbs free energy of the system at constant temperature and pressure, was used for systems containing gas hydrates. The solid hydrate phase was treated as a solid solution. The fugacities of all components of the hydrate phase were calculated as a function of compositions by the rearranged model of van der Wa...

ABSTARCT: As a result of geophysical researches in non-conventional energy sources in the earth in recent years, the discovery of large gas hydrate accumulations in terrestrial permafrost regions of the Arctic and beneath the sea along the outer continental margins of the world's oceans creates the interest of gas hydrates as a possible energy resource. Gas-hydrates are crystalline form in whic...

Gas hydrates are ice-like deposits containing a mixture of water and gas; the most common gas is methane. Gas hydrates are stable under high pressures and relatively low temperatures and are found underneath the oceans and in permafrost regions. Estimates range from 500 to 10,000 giga tonnes of carbon (best current estimate 1600-2000 GtC) stored in ocean sediments and 400 GtC in Arctic permafro...

In recent years, the feasibility of utilizing gas hydrates in industrial systems draws much attention as a subject of engineering studies. Despite the suggested applications for gas hydrate in transportation and storage of natural gas, desalination of water, etc., there have been few applied industrial experiences with gas hydrates. There are several patents and papers on promotion of gas hydra...

A Raman spectrometer extensively modified for deep ocean use was used to measure synthetic hydrates formed in an ocean environment. This was the first time hydrates formed in the ocean have been measured in situ using Raman spectroscopy. Gas hydrates were formed in situ in the Monterey Bay by pressurizing a Pyrex cell with various gas mixtures. Raman spectra were obtained for sI methane hydrate...

Porous materials have provided us unprecedented opportunities to develop emerging technologies such as molecular storage systems and separation mechanisms. Pores have also been used as supports to contain gas hydrates for the application in gas treatments. Necessarily, an exact understanding of the properties of gas hydrates in confining pores is important. Here, we investigated the formation o...

in this study, mass transfer coefficients (mtc’s) of natural gas components during hydrate formation are reported. this work is based on the assumption that the transport of gas molecules from gas phase to aqueous phase is dominant among other resistances. several experiments were conducted on a mixture of natural gas at different pressures and temperatures and the consumed gas was monitored an...

The super-saturation condition has to be provided to form gas hydrates. Consequently, the prediction of the guest molecule fraction in the aqueous phase is crucial in the study of the gas hydrate kinetics. In the present work, several experiments were carried out in a semi-batch reactor in order to determine the mole fraction of methane and ethane during gas hydrates formation (growth stage...