CCUS‐enhanced oil recovery (EOR) technology relies on the unique properties of CO₂ gas in the process of efficient oil displacement while achieving effective storage, which has become one of the most economical and effective measures for reducing greenhouse gas emissions in today's society and is important for helping to realize the global strategic goal of carbon neutrality. Based on previous research results, this review presents the oil displacement and geological storage mechanisms of CO₂ in micropores in the oil and gas fields, and summarizes their respective influencing factors. At the same time, it also summarizes the current research status of CO₂‐EOR and geological storage from the perspectives of laboratory experiments and numerical simulations. Moreover, it provides a detailed overview of four key technologies namely, miscibility improvement, swept volume expansion, storage potential assessment and storage safety monitoring, and their field applications. On this basis, this review compares the development status of field applications in Developed Countries and China, analyzes the problems of CCUS‐EOR technology in theoretical research, technology research and development and project industrialization, and points out the future development directions. Results are presented that research on CO₂‐EOR and geological storage in Developed Countries such as the United States started early and developed rapidly. A relatively complete industrial chain system has been formed, and the scale and number of CCUS‐EOR projects are far ahead those in China. In China, relevant research started relatively late and developed slowly at the early stage. In recent years, due to the notable attention given to climate change and carbon storage, development efforts in China have gradually intensified. At present, there are more than 20 large‐scale CCUS‐EOR demonstration projects in operation, which are preliminarily ready for industrial promotion. Notably, the world has continued to increase its attention to CCUS‐EOR projects based on national conditions, further improving policy guidance mechanisms, strengthening research and development efforts, promoting the construction of the full‐process industry chain, achieving large‐scale and refined development, and providing theoretical guidance and technical support for realizing the strategic goal of carbon neutrality.

Reservoir heterogeneity significantly affects reservoir flooding efficiency and the formation and distribution of residual oil. As an effective method for enhancing recovery, polymer–surfactant (SP) flooding has a complex mechanism of action in inhomogeneous reservoirs. In this study, the effect of reservoir heterogeneity on the SP drive was investigated by designing core parallel flooding experiments combined with NMR and CT scanning techniques, taking conglomerate reservoirs in a Xinjiang oilfield as the research object. The experimental results show that inter-layer heterogeneity significantly affects water flooding efficiency and SP driving in low-permeability cores—the larger the permeability difference is, the more obvious the effect is—while it has almost no effect on high-permeability cores. The limited recovery enhancement in low-permeability cores is mainly due to the small percentage of contributing pores. When the permeability difference undergoes an extreme increase, the polymer molecular weight is biased towards higher values; when the polymer molecular weight is fixed, the recovery enhancement of low-permeability cores may be comparable to that of high-permeability cores when the permeability difference is extremely small. However, the recovery enhancement of the former is smaller than that of the latter when the permeability difference is extremely large. Due to intra-layer heterogeneity, there is a serious fingering phenomenon in the flooding stage, while in the SP flooding stage, recovery enhancement is most significant in the 5–20 μm pore range. This study provides an important geological basis for the rational development of a chemical flooding programme.

To achieve the efficient utilization of low-permeability tight sand and gravel reservoirs with strong heterogeneity in the Mahu oil area of Xinjiang, CO₂ injection is used to improve oil recovery. The sweep pattern of the injected gas is closely related to the development of reservoir pores and throats. Firstly, a three-dimensional model of the average pore-throat radius was established based on complete two-dimensional nuclear magnetic resonance scanning data of the target layer’s full-diameter core in the Wuerhe Formation. Subsequently, an online NMR injection CO₂ continuous oil displacement experiment was conducted using tight conglomerate rock cores to clarify the rules of CO₂ oil displacement in each pore-throat interval. Finally, the three-dimensional pore-throat model was combined with microscopic utilization patterns to quantitatively characterize the reservoir utilization rate of the CO₂ displacement oil and guide on-site dynamic analysis. The research results indicate that the reservoir space of the Wuerhe Formation is mainly composed of residual intergranular pores, accounting for 40.9% of the pores, followed by intragranular dissolution pores and shrinkage pores. The proportion of pore-throat coordination numbers less than 1 is relatively high, reaching 86.3%. The average pore-throat radius calculation model, established using online NMR data from the continuous coring of full-diameter cores, elucidates the characteristics of the average pore-throat radius in the Wuerhe Formation reservoir. Based on gas displacement experiments that explored the pore-throat behavior at the microscale, the calibrated CO₂ injection oil recovery rate was determined to be 43.9%, and the proportion of reserves utilized within the main range during CO₂ displacement amounted to 60.77%. The injection pressure is negatively correlated with the maximum pore-throat radius of the gas injection well group, and negatively correlated with the proportion of the 0.9~2 μm distribution of large pore throats in each gas injection well group.