Field practices of CO2 flooding have shown that CO2 is easier to enter small pores than water, thereby some low-meability and low-saturation non-oil layers are activated to form new effective permeable reservoir bodies, which are defined as potential layers for CO2 flooding. Taking the CO2 flooding reservoir in Jilin Daqingzijing Oilfield as an example, a method for describing and charactering the potential layers for CO2 flooding is established by comprehensively using the data of displacement experiments, geochemical analyses, well logs and section tests. This method involves three key steps: (1) determining the displacement utilization lower limit through laboratory experiments; (2) defining sedimentary genesis via geochemical data; and (3) calibrating well logs with core data to achieve single-well identification, followed by delineating lateral connectivity boundaries based on microfacies-controlled connectivity patterns. This work clarifies the significance of these potential layers for CO2 flooding development and provides a robust geological basis for maximizing CO2 flooding recovery efficiency. The results show that the lower permeability threshold for CO2 flooding potential layers in the study area is 0.06×10-3μm2, with a general permeability range of 0.1×10?3μm2—0.06×10?3μm2. The clay content of these potential layers ranges from 10% to 15%, while carbonate content falls between 6% and 12%. Their genesis is primarily associated with hydrodynamic transition zones and weakly cemented calcareous bands. A three-step progressive logging recognition method was formed for these potential layers, comprising qualitative judgment via characteristic log values, top and bottom boundary division by log curve image overlap, and fine-scale recognition using a high-precision permeability explanation model. Additionally, 6 vertical section developmental patterns of potential layers within different deltaic microfacies established. 5 kinds of CO2 flooding connectivity comparison models were constructed, defining principles for delineating connected CO2 flooding units. The quantitative evaluation revealed that, compared to water flooding, the connectivity rate of the dominant microfacies in CO2 flooding increased by 18.9 percentage points, with connected thickness increasing by 1.7m. For non-dominant microfacies, the connectivity rate increased by up to 34.2 percentage points, and the connected thickness increased by 1.1m. Furthermore, 5 combination types between potential layers and oil layers were established. The study clarified the primary technical measures for stabilizing production and increasing oil output after introducing potential layers into the CO2 flooding scheme. As a result, the CO2 flooding sweep increment can be increased by 18 percentage points, and oil recovery rate by 9.6 percentage points. The findings highlight that CO2 flooding potential layers are the crucial geological research parameter that should be incorporated into both CO2 flooding development plans and dynamic performance analysis.