Abstract: CO₂ flooding and storage have the potential to significantly mitigate greenhouse gas emissions and contribute to achieving carbon neutrality objectives. Nevertheless, current methods for calculating CO₂ storage capacity primarily concentrate on rough estimates of static CO₂ storage, neglecting variations in CO₂ storage during actual production processes. In view of the above problems, the process of CO₂ flooding and storage is divided into gas phase zone, two-phase or near-miscible phase zone, diffusion zone and oil phase zone by using CO₂ dissolution, CO₂ swept volume and oil displacement mechanism. Based on the four-zone method, the CO₂ storage capacity is calculated, and the dynamic CO₂ storage capacity under varying hydrocarbon pore volume multiples, injection pressure and gas injection rate is obtained. The research results are applied to the low permeability reservoir of W oilfield. The results show that the pore volume multiple, pressure and gas injection rate of injected hydrocarbons are positively correlated with the total storage capacity. When the pressure increases from 12 MPa to 30 MPa, the total amount of CO₂ storage increases by 15.53×10⁴ t; when the gas injection rate increases from 5 t/d to 30 t/d, the total amount of peak CO₂ storage increases from 3.51×10⁴ t to 12.62×10⁴t. The research results can provide new ideas for the development of CO₂ flooding and storage projects in similar reservoirs.

Key words: CCUS, CO₂ storage, "four-zone" method, low permeability reservoir