Conformance control design for CO₂ geological utilization and storage with case studies in Yanchang and Shengli CCUS pilot projects

CO₂ utilization and sequestration in hydrocarbon reservoirs are currently the most feasible and economically attractive way to realize large scale carbon reduction (at megaton, even gigaton scale). However, issues such as CO₂ channeling and leakage due to geological heterogeneities/non-integrities and engineering factors, seriously reduce the performance and safety of CO₂ utilization and sequestration. In this study, we tested the performance of smart hydrogel materials in solving the channeling and leakage issues of Yanchang and Shengli CCUS Pilot Projects. To use the smart materials effectively, we proposed a framework to regulate the multiphase flow behavior in the reservoir to achieve more efficient carbon utilization and storage. First, the mechanisms by which channeling control treatment measures affect sweep efficiency and oil displacement efficiency are explored based on core scale experiment and numerical simulation methods, confirming the potential application of this design method for CO₂ miscible flooding. The results demonstrate that, under miscible conditions, the conformance treatment significantly improves the uniformity of CO₂ front displacement and substantially enhances the extraction of medium and heavy oil components. Second, the introduction of a new target parameter—the spatiotemporal miscible coefficient (F_m)—is shown to have a strong positive correlation with both oil recovery and CO₂ storage efficiency. We systematically demonstrate the effectiveness of the proposed framework by applying it to real field CCUS projects, taking a typical low-permeability sandstone reservoir at Yanchang Oilfield in Ordos Basin as an example. The results demonstrate remarkable potential of the proposed methodology in helping the non-beneficial project with traditional CO₂ flooding philosophy to revive to be economically attractive. Compared to the untreated case, the optimized CO₂ flooding under the new channeling control treatment design results in a 13.1-percentage-point increase in hydrocarbon recovery, attributed to the more balanced CO₂ front and the formation of a fully miscible zone between injection and production wells. CO₂ storage efficiency improves by 16.1 percentage point, owing to the significant increase in CO₂ trapped in the porous media and structural storage during full-scale miscible flooding. We also proposed to sequentially regulate the multiphase flow by WAG and gel treatment at proper stages during the project development. This work demonstrates the potential of the proposed innovative conformance treatment design method to improve both oil recovery and CO₂ storage. Above all, this work provides insights from laboratory to field scale studies for effective application of smart hydrogel materials to achieve large-scale geological CO₂ utilization and storage.