<p>CO₂ flooding and storage technology is an important approach to achieving the “dual carbon” goals, offering both emission reduction and economic benefits. This paper systematically analyzes the oil displacement and storage mechanism of this technology. Through the research system of comparing the Enhanced Oil Recovery, effective and actual storage capacity, and by using the methodological criticism and model optimization path analysis, it proposes a six-category calculation method system for the Enhanced Oil Recovery storage capacity, and reveals its applicable conditions and technical bottlenecks, providing a scientific paradigm for the construction of a cross-scale storage prediction system. The existing calculation methods are based on the generalized material balance equation to construct the carbon flux conservation relationship, but the static reservoir assumption restricts the multi-mechanism collaborative characterization of heterogeneous reservoirs. The models of structural storage, residual gas storage, dissolution storage and mineral storage have the defects of mechanism separation and parameter idealization, and are only suitable for the pre-evaluation of storage potential. The calculation method for depleted reservoirs only considers structural storage, while water injection development/water invasion reservoirs need to couple dissolution dynamics. The model based on the analogy method, due to its reliance on CO₂-Enhanced Oil Recovery project data, is more suitable for mature development blocks. The effective storage capacity method realizes potential grading through the screening of geological unit storage coefficients, while the actual synchronous storage model introduces the CO₂ oil replacement rate parameter, which can accurately quantify the storage space of low-permeability reservoirs.</p>