MRI measurements of CO2-CH4 hydrate formation and dissociation in porous media

The sequestration of CO2 in natural gas hydrate reservoirs is an attractive idea for both yielding CH4 and reducing CO2 emissions. To investigate the kinetics of CO2-CH4 gas mixture hydrate formation and dissociation, two types of CO2-CH4 gas mixtures were applied to form hydrates in porous media with different porosities. The process of hydrate formation and dissociation was monitored in situ by magnetic resonance imaging (MRI) in this study. Hydrate saturation was calculated quantitatively using the mean intensity (MI) of each image. The results showed that the hydrates first formed in the centre of the porous media and then grew along the axis of the vessel. The hydrate saturation and the initial water saturation were linearly correlated when the initial water saturation changed from 5% to 40%. By comparing the formation process of two different CO2-CH4 gas mixtures, the formation rate of the 79.8% CO2/20.2% CH4 gas mixture hydrate was faster. The MRI data gave excellent information on the spatial distribution of water in the porous media during hydrate growth and dissociation.