Numerical analysis of phase transition of mining cavity in hydrate solid fluidization exploitation coupled multi-field

Le résumé fourni par la source

Natural gas hydrate reserves are vast, and the exploitation often entails complex phase transitions. Nevertheless, the potential microphase transition within the cavity has been ignored in solid fluidization mining. In this paper, referencing the actual extraction parameters, a multi-field coupling model of computational fluid dynamics -thermo-hydro-chemo has been established to elucidate the extraction cavity phase transition. The partial and ordinary differential equations in the model are solved numerically via the fully implicit finite element technique. The results show that the phase transition zone of the hydrate reservoir spans 35–114 mm at the mining cavity wall. A rapid phase transition occurs at the cavity wall due to the temperature and recovery pressure differences, leading to the water accumulation in the cavity. Although the jet water temperature has a more significant effect on the phase transition degree, the recovery pressure drop has a wider sweep range in the reservoir. Our study verifies the reliability of the model based on Masuda’s experimental data and offers valuable insights for evaluating the possibility of solid fluidization mining.

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