A multi-scale framework for selecting CO2 storage sites in oil and gas reservoirs Multi-scale framework for CO2 storage site selection in oil and gas reservoirs

Yinbang ZHOU

Quantified screening of sites for CO2 geological storage is fundamental to ensuring both the economic viability and safety of CO2 sequestration. However, existing site selection methodologies—domestically and internationally—predominantly rely on qualitative approaches. The operational indicators for storage site selection remain incomplete and lack comprehensive quantitative characterizations. In response, this study presents a comparative analysis of site selection classification schemes for aquifers located in oil and gas regions. It clarifies the stratified levels of site selection for these aquifers and proposes a corresponding site selection process, along with a robust indicator system tailored for CO2 geological storage. Additionally, a case database for CO2 geological storage was developed. This database integrates qualitative comparative selection with semi-quantitative screening based on analytic hierarchy process (AHP). Using this hybrid approach, the study quantitatively prioritizes favorable structural storage bodies, creating a tiered site selection methodology. This method enables three-dimensional identification, extraction, and potential evaluation of structural formation suitable for CO2 storage using geological modelling. The approach has been successfully applied to aquifer site selection in the oil field A, providing prioritized targets for CO2 storage site selection across different aquifer levels. This stratified site selection framework lays a solid foundation for large-scale CO2 geological storage. It is of critical importance for conducting comprehensive research and field demonstrations of carbon capture, utilization, and storage (CCUS) technologies. Moreover, it supports the advancement of national dual-carbon objectives.