Methane hydrate formation in partially water-saturated Ottawa sand (original) (raw)

Kinetics of methane hydrate formation and dissociation in 1 sand sediment 2 3

2019

15 Methane hydrate is being considered as a potential future energy source but may at 16 the same time constitute a considerable geo-hazard. In the present study, methane 17 hydrate bearing sand sediment was created by pressurizing methane gas into 18 previously moistened, then chilled, packed sand specimen (excess gas method). The 19 excess gas was then replaced by water at high pressure. Afterward, a 20 heating/cooling cycle was applied under undrained conditions, in order to completely 21 dissociate gas hydrates and then recreate them inside the specimen. Finally, the 22 pore pressure was reduced to the atmospheric pressure to dissociate gas hydrates. 23 The whole process was performed in a magnetic resonance imaging (MRI) system, 24 allowing the determination of water and/or gas and hydrate quantity (and spatial 25 distribution) at various times. The MRI signal was finally analyzed to interpret various 26 processes in sand sediment: initial hydrate formation, heating-induced hyd...

Influence of Water Saturation, Grain Size of Quartz Sand and Hydrate-Former on the Gas Hydrate Formation

Energies, 2021

The development of technologies for the accelerated formation or decomposition of gas hydrates is an urgent topic. This will make it possible to utilize a gas, including associated petroleum one, into a hydrate state for its further use or to produce natural gas from hydrate-saturated sediments. In this work, the effect of water content in wide range (0.7–50 mass%) and the size of quartz sand particles (porous medium; <50 μm, 125–160 μm and unsifted sand) on the formation of methane and methane-propane hydrates at close conditions (subcooling value) has been studied. High-pressure differential scanning calorimetry and X-ray computed tomography techniques were employed to analyze the hydrate formation process and pore sizes, respectively. The exponential growth of water to hydrate conversion with a decrease in the water content due to the rise of water–gas surface available for hydrate formation was revealed. Sieving the quartz sand resulted in a significant increase in water to h...

Physical properties of hydrate-bearing sediments

Reviews of Geophysics, 2009

[1] Methane gas hydrates, crystalline inclusion compounds formed from methane and water, are found in marine continental margin and permafrost sediments worldwide. This article reviews the current understanding of phenomena involved in gas hydrate formation and the ...