In the early stages, the "horizontal well and hydraulic fracturing" technology was adopted to develop low permeability reservoirs by Jilin Oilfield. Subsequently, it has entered the tight oil development stage, characterized by rapid production decline, low formation pressure, slow oil recovery rate, and low recovery efficiency. There is an urgent need to research energy supplementation technologies to enhance recovery efficiency further. To evaluate the feasibility and potential of CO₂ water-alternating-gas (WAG) injection in the Q block of the Jilin oilfield, systematic research was conducted through long core displacement experiments and micro-simulation methods, including the difference of displacement characteristics and micro-fluid distribution laws of different types of cores in different displacement methods, and core scale and pore throat scale were combined. The results show that for fractured long cores, the highest oil displacement efficiency is achieved at a water-gas ratio of 1∶2, and the efficiency decreases as the gas slug size increases. The final oil displacement efficiencies for the three water-gas ratios are 60.4%, 53.6%, and 50.2%, respectively. For conventional long cores, the highest oil displacement efficiency of 72.8% is achieved at a water-gas ratio of 1∶1. Overall, WAG flooding development significantly outperformes continuous water flooding and continuous gas flooding, improving oil displacement efficiency by 28% and 12%, respectively. Additionally, by comparing the experimental results of different types of cores, it is found that the presence of fractures significantly reduces the oil displacement efficiency and increases the risk of gas channeling. Utilizing microscopic simulation technology, this results further elucidates the mechanism by which the Jamin effect of the water slug blocks gas channeling in high-permeability layers during WAG, thereby improving recovery efficiency. These research findings provide significant reference value for the rational selection of water-gas slug ratios in developing different types of reservoirs in the Jilin Oilfield.