| 초록 |
Replacement has been considered as a promising method for CO2 sequestration as well as CH4 recovery because CO2 can be stably stored in natural gas hydrate (NGH) reservoirs without weakening geo-mechanical strength of the sediment layer via spontaneous guest exchange. Three structures of NGHs (sI, sII, and sH) in nature have been discovered in various explorations. Because of the distinctive characteristics of each structure, the replacement mechanism in each hydrate structure should be studied individually. In this study, the guest exchange behavior in sII (CH4 + C3H8) hydrate – CO2 + N2 was investigated to elucidate the influence of feed gas compositions on the sII hydrate replacement. The extent of replacement was measured via gas chromatography. Structural transformation before and after replacement was confirmed via 13C NMR and PXRD analyses. The experimental results demonstrated that CO2 was more selectively enclathrated in the sII hydrate at a higher CO2 composition in the feed gas, even though replacement efficiency was not much different. The finding of this study would be helpful for understanding the replacement mechanism in sII hydrates using flue gas injection. |
