Investigation on the Heat and Mass Transfer Characteristic During the Natural Gas Hydrate Exploitation

A heterogeneous hydrate reservoir model with low-permeability was constructed in this study to investigate the mechanisms of heat and mass transfer, hydrate dissociation, and capillary pressure variations during hydrate extraction using a combination of hot fluid injection and depressurization. The results show that the temperature increase in the hydrate layer was significantly lower compared to the mixed layer and the upper part of the gaseous hydrocarbon layer, indicating that horizontal hot water seepage plays a more significant role than vertical movement. Additionally, a temperature inflection point was observed in the mixed layer and the upper gaseous hydrocarbon layer. During the mid-to-late stages of extraction, a sharp rise in capillary pressure was detected near the injection well in the hydrate layer, driven by decreasing water saturation and increasing gas saturation, which enhances the potential for water lock effects in certain regions of the hydrate layer.