The use of hydrate-based technology for CO2 sequestration in permafrost layers is a promising and potential CO2 sequestration technique.In order to investigate the influence of formation properties on CO2 sequestration,CO2 hydrate synthesis experiments were conducted under the conditions of initial pressure of 5.5 MPa and temperature of 1.27℃and the influence of different mineral compositions and particle size ratio of fine-grained.The pressure-temperature changes,CO2 hydrate average synthesis rates,CO2 consumptions,and phase saturations during the CO2 hydrate formation process were analyzed during the experiment.The results show that the CO2 hydrate average synthesis rate is the smallest when the ratio of fine-grained sand to coarse-grained sand particle sizes(mass ratio of each component,the same below)is 1.0:2.0,which is 12.60 mmol/min.With the increase of coarse sand proportion,the CO2 hydrate average synthesis rate decelerateds due to the reduction of specific surface area.Montmorillonite clay is not conducive to CO2 hydrate formation,and the CO2 hydrate average synthesis rate of the silty sand group(contains fine-grained sand and coarse-grained sand)is higher than that of the silty clay group(contains fine-grained sand and montmorillonite clay).And the experiments in the silty sand group are more likely to achieve high hydrate saturation and CO2 consumption,making it more suitable for CO2 sequestration in areas with mineral compositions containing fine-grained sand and coarse-grained sand.The CO2 consumption rates for the ratio of fine-grained sand to coarse-grained sand or clay mineral particle sizes of 1.0:0.5 are 0.86 mol and 0.77 mol,respectively.With the increase of the proportion of coarse-grained sand and clay minerals,both the hydrate saturation and CO2 consumption gradually decrease.The ratio of fine-grained sand to coarse-grained sand or clay mineral particle sizes of 1.0:0.5 is suitable for CO2 sequestration using the hydrate-based method.
CO2hydratecarbon sequestrationclyey-siltparticle size ratio
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