Abstract: To investigate the interactions between CO₂ and CH₄ in aqueous phase and their competitive dissolution effects on CO₂-enhanced oil recovery processes, a numerical simulation model incorporating the competitive dissolution of CO₂ and CH₄ was developed. The established model modifies the solubility of CH₄ at different CO₂ concentrations and improves the equilibrium constants that characterize methane solubility. Simulation results indicate significant changes in the distribution of gas components due to competitive dissolution, affecting the gas-oil ratio and water cut fluctuations, thereby impacting the production performances of the reservoir. Under competitive dissolution, the CH₄ content in the gas phase increases, further confirming the complexity of interactions between CH₄ and CO₂. This model accurately reflects gas interactions during the CO₂ flooding process.