CO2 trapping mechanism in deep saline aquifers under the control of composite geological factors: A numerical case study in China

Abstract

The increasingly intensifying global climatic change necessitates carbon capture and storage. Reservoir physical properties including porosity, permeability, temperature, and pressure directly control the spatial migration, storage forms, and storage capacity of CO₂ in saline aquifers. Based on China’s first CCS demonstration project in saline aquifers, this study constructed a water-CO₂-thermal-chemical coupling model for long-term CCS in reservoirs. The results indicate that the deep saline aquifers in the Ordos Basin are favorable for CO₂ mineral trapping, with a mineralization storage amount reaching up to 64.02 % of the total injection amount at 1000 years. Temperature is identified as the most significant factor influencing safe CO₂ mineral trapping under CO₂ injection. The study not only provides valuable insights into the mechanisms of CO₂ trapping but also lays a foundation for optimizing the design of ongoing CCS projects and evaluating site suitability for future projects, facilitating progress toward China's carbon neutrality target.