Carbon dioxide (CO₂) geological storage (CGS) is considered as one of the feasible choices for large-scale CO₂ emission reduction worldwide, and the primary issue in CGS is how to select areas favorable for storing CO₂. The research conducted by Chinese scholars on CO₂ geological storage in the Ordos Basin has mainly focused on numerical simulations of CO₂ storage, the estimation of the CO₂ storage capacity, and the CO₂ storage mechanism. Few studies have been conducted on the selection of CO₂ geological storage area, or even on a methodology for ranking CO₂ geological storage sites in carbonate reservoirs. This study provides a reference for the ranking of CGS areas in carbonate reservoirs. First, from the geological view of CO₂ storage reservoir, logging data and core petrographic analyses with cast thin sections, scanning electron microscopy and formation water salinity tests were used to systematically investigate the reservoir type, lithology, porosity, permeability, burial depth, thickness, temperature, and pressure conditions, and water salinity of the Majiagou formation. Second, from the perspective of CO₂ storage safety, literature research, and seismic interpretation data were used to investigate the sealing performance of the strata overlying the Majiagou Formation and its related fault system in detail. Third, from the economic perspective of CO₂ storage, considering the distance from the source of the CO₂ emissions, the extent of the regional exploration, and the degree of the influence of CO₂ storage on the exploitation of other mineral resources, the CO₂ storage areas in the Majiagou Formation in the Ordos Basin were prioritized. The results show that (1) the Wushenqi-Jingbian-Yan'an karst slope area (I₁) is the best CO₂ geological storage area, (2) the Yulin-Mizhi karst basin area (I₂) is a favorable area for CGS in the Ordos Basin. (3) A site ranking methodology for CGS is also proposed, providing a reference for the selection of CO₂ geological storage areas in carbonate reservoirs based on the technical, safety, and economic feasibility of the CGS.

二氧化碳(CO ₂ )地质封存(CGS)被认为是世界范围内大规模CO ₂减排的可行选择之一，而CGS的首要问题是如何选择有利于封存CO _{2 的区域}。我国学者对鄂尔多斯盆地CO ₂地质封存的研究主要集中在CO ₂封存数值模拟、CO ₂封存容量估算、CO ₂封存机理等方面。关于CO ₂地质封存区的选择，甚至CO ₂分级方法的研究很少碳酸盐岩储层中的地质封存点。本研究为碳酸盐岩储集层CGS区位排序提供参考。首先，从CO ₂封存储层地质学角度，通过测井资料和铸薄岩心岩相分析，利用扫描电镜和地层水矿化度测试，系统地考察了储层类型、岩性、孔隙度、渗透率、埋藏深度、厚度马家沟组的温度、压力条件和水盐度。二、从CO ₂的角度利用储存安全性、文献研究和地震解释资料，详细研究了马家沟组上覆地层及其相关断层系统的封闭性。第三，从CO ₂封存的经济角度，考虑到CO ₂排放源的距离、区域勘探程度以及CO ₂封存对其他矿产资源开发的影响程度，CO ₂鄂尔多斯盆地马家沟组储集区_2个。结果表明：（1）乌慎旗-靖边-延安岩溶斜坡区（I ₁）CO ₂最佳(2)榆林-米脂岩溶盆地区(I ₂ )是鄂尔多斯盆地CGS的有利区。(3) 提出了CGS的选址排序方法，为基于CGS技术、安全和经济可行性的碳酸盐岩储层CO ₂地质封存区的选择提供参考。