Carbon dioxide-enhanced oil recovery (CO₂-EOR) technology has been proven to be effective approach for enhancing oil recovery and has been used in conventional reservoirs since 1970s. Tight sandstone reservoir has poor petrophysical properties, and the complex diagenetic processes that make the reservoir highly heterogeneous resulted in posing significant challenges to CO₂-EOR technology. This paper investigated the effects of macroscopic permeability heterogeneity on the efficiency of CO₂-EOR by laboratory experiments and field data analysis. The permeability heterogeneity of the reservoir matrix in the study area was evaluated. The results reveal that the matrix permeability range from 0.001 mD to 15 mD, with a mean approximant 1 mD, Beside common thin bedding laminations, the areal permeability varies significantly in a short distance, which is typical for a tight sandstone reservoir. The Triassic Yanchang Formation (200–1400 m thick) is a major petroliferous stratigraphic section in the Ordos Basin. It consists of complete lacustrine sedimentary cycles with clastic sediments. From bottom to top, it can be divided as Chang 10 to Chang 1 members. The low porosity, low permeability, low oil saturation, anomalously low reservoir pressure, and high reservoir heterogeneity makes application of enhanced oil recovery techniques in this formation challenging. The submerged distributary channel core sample with various permeability from the Chang 4+5 sandstone reservoir in Shanbei area of the Ordos Basin were utilized in the laboratory CO₂-EOR experiments to study the impact of heterogeneity on CO₂ flooding. The results show that the mode of high–low permeability (i.e., the injection well located in the higher permeability area and the production well located in the low permeability area) can ensure the gas injection capacity, maintain a high pressure level throughout the production period, and increase the oil displacement efficiency, which breaks the conventional understanding. Conventional understanding holds that high permeable pore path or fractures developed on the injection area are prone to CO₂ channeling, and high permeable pore path or fractures developed on the production area are conducive to oil flow and output increase. Therefore, oil well fracturing is often carried out in the field, and fracturing of injection well is not recommended. However, our experimental research and field application found that the traditional guiding ideology is not conducive to improve oil recovery, but the high–low permeability model which is put forward in this paper can not only enhance CO₂ injectivity, but also is beneficial to high formation pressure level and full interaction between gas and crude oil. It also can be confirmed from oilfield that the application of high-low permeability model with high-heterogeneity reservoir could effectively improve the effect of CO₂ flooding in tight sandstone reservoirs.

二氧化碳增强的石油采收（CO ₂ -EOR）技术已被证明是提高石油采收率的有效方法，并且自1970年代以来已在常规油藏中使用。致密砂岩储层的岩石物性较差，复杂的成岩作用使储层高度非均质，这对CO ₂ -EOR技术构成了重大挑战。本文研究了宏观渗透率非均质性对CO ₂效率的影响通过实验室实验和现场数据分析提高采收率。评价了研究区储层基质的渗透性非均质性。结果表明，基质渗透率的范围从0.001 mD到15 mD，平均约为1 mD，除了常见的薄层理叠片，区域渗透率在短距离内变化显着，这是致密砂岩油藏的典型特征。三叠系延长组（200-1400 m厚）是鄂尔多斯盆地一个主要的含油地层。它由完整的湖相沉积周期和碎屑沉积组成。从下到上，它可以分为Chang 10到Chang 1成员。低孔隙度，低渗透率，低油饱和度，异常低的储层压力，高储层非均质性使得在该地层中应用强化采油技术具有挑战性。利用鄂尔多斯盆地山北地区长4 + 5砂岩储层不同渗透率的淹没式分流河道岩心样品进行了实验室CO分析。₂ -EOR实验，研究非均质性对CO ₂驱油的影响。结果表明，高低渗透率模式（即注入井位于较高渗透率区域，生产井位于低渗透率区域）可以确保注气能力，并在整个生产期间保持较高的压力水平。 ，并提高了排油效率，这打破了传统的理解。传统理解认为，高渗透性孔隙路径或在注入区域形成的裂缝易于产生CO _2。窜，高渗透孔隙路径或生产区域上形成的裂缝有利于油的流动和产量的增加。因此，在现场经常进行油井压裂，不建议注入井压裂。然而，我们的实验研究和现场应用发现，传统的指导思想不利于提高采收率，但本文提出的高低渗透率模型不仅可以提高CO ₂注入量，而且对提高CO ₂注入率也有好处。地层压力水平以及天然气与原油之间的充分相互作用。从油田也可以证实，高非均质油藏高低渗模型的应用可以有效提高CO ₂的效果。 致密砂岩储层中发生洪水。