Taking the Chang 8 tight reservoir in Ordos Basin as an example, the cluster analysis method is used to divide the reservoir into four types of initial flow units according to the five static parameters of effective thickness, porosity, permeability, reservoir quality factor, and oil saturation. On the basis of static parameters, the reservoir in the study area is divided into four types of developed flow units according to the two dynamic parameters of reservoir sand strength and liquid production. The three-dimensional modeling of the flow units before and after development is carried out, and the distribution characteristics of the flow units are analyzed. Combined with the numerical simulation of remaining oil, some suggestions are put forward for the subsequent reservoir potential tapping scheme. The research shows that the distribution of sedimentary facies controls the distribution of static flow units, and the high-level flow units extend along the main channel. The thickness of sand bodies is large, and the sand bodies are superimposed and continuously distributed. The low-level flow units are distributed on both sides of the main channel, the thickness of the sand body becomes smaller, and the sand body is separated. The development method controls the dynamic flow unit. After fracturing, the flow unit around the well is generally better than the inter well flow unit. After stage oil recovery and fracturing, the fluidity of the Class A and Class B of flow unit and the initial high value of oil saturation increases while the oil saturation decreases, resulting in the remaining oil-rich area being transformed into Class C and Class D flow units with relatively poor fluidity. Based on the distribution of developed flow units and the distribution characteristics of remaining oil, the reservoir can be divided into six potential tapping levels. The remaining oil content and developed flow unit level of the first-level potential tapping reservoir are high, which is the preferred area for the next production and development. The developed flow unit level of the second-level potential tapping reservoir is low but the remaining oil content is high, which can be jointly developed with the first-level potential tapping reservoir. The research provides reference for the study of flow units and the adjustment of later development schemes in the same type of tight oil reservoirs.

CO₂ geological storage in saline aquifers is an effective carbon neutrality technology. The Zhifang Formation has a moderate burial depth, relatively low drilling costs, and does not conflict with oil and gas development. Research on the development and distribution patterns of its saline aquifers and the potential for CO₂ geological storage in these aquifers has practical significance for implement CO₂ saline aquifer geological storage projects in the study area. The main rock types of the Zhifang Formation reservoir are medium-grained lithic feldspar sandstone and feldspathic lithic sandstone, with pore fillings primarily composed of cement, mainly montmorillonite, illite/montmorillonite mixed layers, and chlorite/montmorillonite mixed layers. The Zhifang Formation has an average porosity of 12.55% and permeability of 4.54 mD, classifying it as a low-porosity and ultra-low permeability reservoir. The main pore types are dissolution intergranular pores, followed by dissolution intragranular pores. The average maximum pore throat radius of the Zhifang Formation is 7.04 μm, with an average median radius of 0.25 μm. The pore distribution concentration in the 5th member of the Qian Formation is higher than that of the Zhifang Formation. The average single-layer thickness of the saline aquifer in the 3rd member of the Zhifang Formation is 6.7 m, with an average cumulative thickness of 15.6 m. The average single-layer thickness of the saline aquifer in the 4th member is 5.1 m, with an average cumulative thickness of 11.7 m. The high-value areas of the Zhifang Formation saline aquifer thickness are controlled by distributary channel sand bodies, showing a north-northeast trending strip distribution. The total storage capacity of the Zhifang Formation in the study area is 13461×10⁴ tons. Due to the greater burial depth in the western part of the study area, resulting in higher reservoir temperature and pressure, the CO₂ density is increased compared to the eastern part, leading to greater storage potential.