Molecular Dynamics Simulation of the Influence of CO₂ and N₂ Gas-to-Oil Ratios on the Emulsification Process in...

Heavy oil reserves constitute over 70% of global crude oil resources, yet their extraction remains challenging due to high viscosity and poor flowability. Multicomponent thermal fluid (MTF) technology, integrating CO₂, N₂, and steam, offers a promising solution by enhancing emulsification and mobility. This study employs molecular dynamics (MD) simulations to unravel the microscale emulsification mechanisms of heavy oil under MTF. By systematically varying gas-to-oil ratios (R), we identify favorable ratios of R = 1.3 for CO₂ and R = 0.85 for N₂, validated through analyses of diffusion coefficients and radial distribution function (RDF). The addition of MTF increased the diffusion coefficient of the oil droplets to 0.9565 × 10^-8 m²/s, which is 56.4% higher than the effect of the CO₂ system and 85.6% higher than the effect of the N₂ system. This improved transport behavior correlates with emulsion stabilization mechanisms evidenced by distinct RDF peaks at interfacial separation distances of 0.40 nm (Oil-CO₂) and 0.51 nm (Oil-N₂). The results demonstrated that the combination of CO₂, N₂, and H₂O significantly facilitated the dispersion of oil droplets and enhanced emulsification. The findings will offer microlevel guidance and theoretical support for efficient heavy oil extraction.