Under the background of the “dual carbon” target, to promote the development of CO₂ gas flooding enhanced oil recovery technology and clarify the key parameters of gas injection enhanced oil recovery, a numerical simulation model was established by fitting experimental data based on long core flooding experiments. The impact of key parameters such as gas injection timing, gas injection rate, irreducible water saturation, and development methods on recovery rate was systematically studied. The results show these as follows. In fractured gas reservoirs, fractures are the main seepage channels. The process of injected gas displacing natural gas is divided into two stages: unbroken and broken. The longer the duration of the unbroken stage, the higher the recovery rate. Increasing the injection pressure can enhance the gas displacement capacity and delay CO₂ breakthrough, which has a positive impact on improving the recovery rate of natural gas and the sequestration rate of CO₂. The faster the gas injection rate, the larger the gas sweep range, and the higher the CH₄ recovery rate, but the CO₂ sequestration rate will decrease. Irreducible water saturation has a certain impact on the recovery rate and sequestration rate. An increase in irreducible water saturation will improve the CH₄ recovery rate but reduce the CO₂ sequestration rate.Advanced gas injection and pressurization can shorten the development time and improve the CH₄ recovery rate, but it will reduce the CO₂ sequestration rate. The results provide a theoretical basis for optimizing CO₂-EGR(exhaust gas recirculation) technology parameters, reducing costs, and improving economic benefits, and it is of great significance for promoting the efficient development of natural gas resources and achieving carbon emission reduction.