The Gao 12 fault block reservoir in Jidong Oilfield is small in scale, low in permeability, and difficult to establish an effective displacement relationship. The injection pressure is high, water injection is difficult, and the water flooding development effect is poor, but the reservoir temperature and pressure are high and suitable Improve oil reservoir recovery through gas injection. Low-permeability oil reservoirs generally have a starting pressure gradient, which has an impact on actual reservoir development. Aiming at the high 12 fault block reservoir, a three-dimensional geological model for the high 12 fault block gas injection development is established. Based on the indoor starting pressure gradient experiment, it is obtained For the formula of starting pressure gradient and permeability, the relationship between starting pressure gradient and permeability change is considered in the numerical simulation software. However, the problem of pipeline corrosion caused by long-term injection of CO2 has become increasingly prominent. As a good energizing gas, N2 combines the two to form a composite gas for throughput, which can alleviate the damage to the pipeline. Using numerical simulation methods, the optimization of single well production, slug ratio, injection timing, injection volume, simmering time, and oil recovery rate during gas injection stage in the depletion stage was carried out. Finally, the optimal injection-production parameters of the block are obtained: the single well production in the depletion stage is 15m3/d; the slug ratio is 7:3; the transfer timing is when the daily oil production rate in the depletion stage drops to 4m3/d; the injection volume is 60000m3 ; The simmering time is 15 days; the oil recovery rate in the gas injection stage is 25m3/d, which provides a method and technology reference for improving the oil recovery of high 12 fault block reservoirs.