A review of CO2 leakage along faults in CCUS: Theories, experiments, and models

Since there have been major issues with the global climate recently, it is critical to cut carbon emissions. Carbon capture, utilization, and storage (CCUS) is a new technology with the potential for large-scale CO₂ emission reduction. Conducting necessary risk assessments before undertaking CCUS, especially geologic CO₂ storage, is an important measure to reduce risks and ensure project safety. In CCUS projects, CO₂ leakage along faults is one of the most critical leakage paths. This research reviews previous studies on CO₂ leakage along faults in CCUS, systematically summarizing fault characterization and theoretical methods related to leakage. Experiments and numerical simulations pertaining to CO₂ leakage along faults are introduced. The study critically evaluates the current limitations of existing research, identifies possible future research directions and issues, and provides a comprehensive overview of the progress in fault leakage and prevention methods research. The key detection methods for CO₂ leakage include sampling monitoring, deformation monitoring, flux monitoring, and pressure monitoring. The main factors influencing CO₂ leakage are the permeability of faults and their long-term evolution. However, current research has several limitations, including the limited scale of experimental models, insufficient research on fault leakage rates, and the lack of direct field monitoring techniques. Additionally, numerical simulations in current studies are overly simplified. This work offers valuable insights for future research on CO₂ leakage along faults and risk management and highlights the necessity for further investigation into these research gaps.