After more than 20 years of technical research and construction of domestic underground gas storage reservoirs, PetroChina has built a gas storage capacity of 196 × 108 m3 by the end of 2023, and still needs to add new peak capacity of 40 × 108 m3 per year by the end of 2027, but the target of high-quality reservoirs has been reduced, and the target of planning for the new construction of reservoirs accounted for 26.6% of the total reservoirs, and the construction of reservoirs with the main reservoir construction technology of conventional gas reservoirs is unable to meet the needs of the new gas storage capacity. Jidong Oilfield started to explore the reservoir construction technology for the first batch of reservoirs in China, the oil, gas and water relationship is complicated before reservoir construction, with the high speed gas injection and extraction operation, the oil, gas and water are driven by each other, the geological conditions of reservoirs and fluid seepage characteristics of reservoirs have a greater impact on the efficiency of storage space utilization of the storage reservoir, in order to improve the recovery rate of water-flooded reservoirs and accelerate the construction of reservoirs, we carried out the simulation experiments of the cycle of injection and extraction of pore space utilization simulations and numerical simulations, and we made a study of the pore space utilization rules of water-flooded reservoirs. The results show that the efficiency of pore space utilization in reservoir construction is mainly affected by non-homogeneity, gas injection rate, gas injection pressure, gas injection method and other factors, which are as follows: (1) The stronger the core non-homogeneity is, the worse the reservoir pore space utilization effect is. (2) The pore space utilization increases and then decreases with the increase of gas injection rate. (3) There exists the upper limit pressure value of gas injection, within the range of this value, the dissolution of injected natural gas increases, the viscosity of crude oil decreases, the pore space mobilization increases, and the increase of reservoir space is obvious; beyond this pressure, the growth rate of pore space mobilization slows down; there exists the lower limit pressure of gas extraction, the closer the lower limit pressure is, the better the pore space mobilization is, and the lower the value is, the rate of increase of pore space mobilization slows down. (4) Pore space utilization is the lowest in the method of only injection but not extraction, and the method of periodical injection and extraction (half-time rate of extraction in the wells with liquid discharge) is favorable to the utilization of pore space.