LAUSR

The application of air or nitrogen injection to extract natural gas from hydrates has attracted considerable attention because air and nitrogen are abundant; however, few studies have considered the relatively new method. This study employed magnetic resonance imaging to investigate the characteristics of hydrate dissociation via N2 injection. The results show that methane hydrate dissociation using N2 injection can be divided into three main stages: free gas and water liberation, hydrate dissociation driven by chemical potential differences, and restriction of hydrate dissociation due to increased resistance to N2 diffusion and a decreased contact area between N2 and hydrate. Various factors associated with the N2 injection method were considered, including injection rate and hydrate saturation. Furthermore, a comparison of recovery:injection ratio and methane cumulative production ratio to the results of hydrate dissociation via depressurization suggests that during low-hydrate saturation exploitation, ...