Evolution and Model Coupling Displacement and Phase Change in Hydrate-bearing Porous Media

The well-developed natural gas often coexists beneath marine hydrate deposits. Both natural phenomena such as cold seeps and natural gas exploitation on the seabed involve the crucial scientific issue of multiphase displacement and phase transition coupling within porous media. Currently, there is a lack of research on the flow of methane within water-saturated hydrate reservoirs, particularly on flow impedance. In this study, we focus on simulating the process of methane seepage within sedimentary layers, with particular attention to two flow stages: displacement and seepage. The results indicated that the capillary action of hydrate layer impeded methane flow during the displacement process, resulting in an increase in flow pressure. After methane broke through the reservoir impedance, it entered the seepage stage. A comparative analysis revealed a significant positive correlation between displacement breakthrough pressure and hydrate saturation in the reservoir. By considering multiple types of interactions between hydrates and fluids, we established a coupled model of multiphase flow and phase transition in hydrate reservoir, with predicted results highly consistent with experimental findings. This study plays a crucial role. © 2024 Science Press. All rights reserved.