Addressing the problem of limited methane (CH4) recovery degree under different production conditions in a target low-permeability carbonate gas reservoir, this study intends to further investigate the effect of carbon dioxide (CO2) injection on enhanced gas recovery (EGR). A group of long-core physical simulation experiments of CO2 injection for EGR was adopted. Field injection–production parameters were converted to laboratory conditions through similarity criteria to simulate the actual production process of gas wells. Systematic experiments on CH4 depletion and CO2 displacement were carried out under different irreducible water saturation, gas injection timing pressure and injection rates. The influence laws of each key parameter on the CO2 breakthrough time and CH4 recovery degree were analyzed emphatically, and the optimal injection–production scheme was obtained. For the target low-permeability carbonate gas reservoir (permeability 7.38 MPa) can increase the CH4 recovery degree by 3–5%. This study provides experimental support for the optimization of CO2 injection schemes for enhanced recovery in gas reservoirs and the adjustment of gas reservoir development strategies under different irreducible water saturation conditions.
Zhang et al. (2026) studied this question.