Kinetic Formation Process of Carbon Dioxide Hydrate in Porous Sands under 274.15–280.15 K Reaction Temperature and 20–70% Initial Water Saturation

Using gas hydrates to store CO₂ is currently considered a promising technology for carbon capture, utilization, and storage with great industrial application prospects. Three groups of phase equilibrium experiments with 72 groups of environmental conditions were arranged to conduct the reaction kinetics of CO₂ hydrate in natural sands. The effects of 20–70% initial water saturation, 274.15–280.15 K reaction temperature, and 0.025–0.2 mm natural sands on the reaction process were analyzed. From test results, the final gas storage of a porous media system is proved to depend largely on the initial water saturation and has a linear relationship with it. The reaction temperature has an insignificant promotion effect on the final gas storage, and the porous sands with a particle size of 0.025–0.055 mm consistently operate at the lowest level in 93.05% of the working conditions. The results reveal that the classic fugacity model has a good fitting effect at lower reaction temperatures (274.15–278.15 K), while the fitting effect will be reduced in other conditions. After inserting the capillary pressure of the van Genuchten style into the modified fugacity kinetic model, the applicability scope and accuracy of the model can be excellently improved.