One of the options suggested for methane recovery from natural gas hydrates is molecular replacement of methane by suitable guests like CO2 and N2. This approach has been found to be feasible through many experimental and molecular dynamics simulation studies. However, the long term stability of the resultant hydrate needs to be evaluated; the decomposition rate of these hydrates is expected to...

Gas hydrates dominated by methane naturally occur in deep marine sediment along continental margins. These compounds form in pore space between the seafloor and a sub-bottom depth where appropriate stability conditions prevail. However, the amount and distribution of gas hydrate within this zone, and free gas below, can vary significantly at different locations. To understand this variability, ...

The porous microstructure of hydrates governs the mechanical strength of the hydrate-bearing sediment. To investigate the growth law and microstructure of hydrates in porous media, the growth process of tetrahydrofuran (THF) hydrate under different concentration of THF solution is directly observed using Magnetic Resonance Imaging (MRI). The images show that the THF hydrate grows as different m...

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...

This paper deals with the effects of a surfactant additive on the formation of methane hydrate in water system with and without sodium dodecyl sulfate (SDS). The properties of sodium dodecyl sulfate are listed. The results manifested that the presence of SDS could not only accelerate the hydrate formation process, but also increase the partition coefficient of methane between hydrate and vapor ...

AIM We hypothesised that chloral hydrate is safe and effective for sedation during dental treatments for children with mild asthma. We evaluated the safety and efficacy of chloral hydrate by measuring changes in heart rate (HR), transcutaneous oxygen saturation, (SpO2), asthma score, behaviour, types and frequency of adverse reactions associated with chloral hydrate were assessed throughout tre...

This proposal is for an IODP program to constrain models for the formation of deep sea gas hydrate in subduction zone accretionary prisms. The objectives include the deep origin of the methane, its upward transport, its incorporation in gas hydrate, and its subsequent loss to the seafloor. The main attention is on the widespread seafloor-parallel layer of dispersed hydrate located just above th...

Gas hydrate formation in production and transmission pipelines and consequent plugging of these lines have been a major flow-assurance concern of the oil and gas industry for the last 75 years. Gas hydrate formation rate is one of the most important topics related to the kinetics of the process of gas hydrate crystallization. The main purpose of this study is investigating phenomenon of gas hyd...

Experimental data on the kinetics of propane hydrate dissociation at 0.1 MPa and different external temperatures were obtained. A two-stage mechanism of hydrate dissociation was observed visually. In the first stage hydrate dissociated into metastable water and gas. During the second stage the metastable water crystallized into ice. The release of metastable water during hydrate dissociation an...

Hydrate slurry has been reported to be a suitable secondary fluid for refrigeration and air-conditioning systems. The latent heat of CO2 hydrate is 387 kJ/kg under phase equilibrium condition of 7 °C and 30 bar. The utilization of CO2 hydrate slurry in air-conditioning systems is promising in improving the energy efficiency and shifting energy supply and demand load as well as relieving greenho...