Inhibition mechanism of solid phase migration and flow channel jamming on the natural gas hydrate dissociation and gas production

In the process of natural gas hydrate exploitation, solid-phase particles tend to migrate in pore channels, resulting in localized flow channel jamming and consequently destabilizing gas production. This presents a significant challenge for the commercial exploitation of hydrates. Therefore, uncovering the influence of solid phase migration in the flow channel holds great importance for achieving more efficient and safe hydrate exploitation. In this study, a gas hydrate exploitation model was established based on the two-fluid model theory, incorporating the formation of ice phase and accounting for solid phase migration-jamming. The results indicate that both gas production rate and gas hydrate dissociation rate decrease due to the influence of hydrate phase and ice phase migration and jamming. This effect is attributed to the increased solid phase saturation as solid particles flow toward the near-wellbore area. Consequently, the absolute permeability of the reservoir is inhibited, limiting the gas–liquid flow capacity, particularly in instances where the flow channel becomes jamming. Convective heat transfer within the reservoir diminishes, leading to a rapid drop in the local reservoir temperature. Simultaneously, the quantity of the ice phase increases within this localized area. However, the migration of solid particles has minimal impact on changes in the reservoir's pressure field. Therefore, variations in the pressure field are not the primary cause of gas production reduction resulting from solid phase migration influence.