Research and application of a new quantitative model for CO2 sequestration in voids created by underground coal gasification

As a key technological pathway for achieving carbon neutrality in the coal sector, a major unresolved challenge for Underground Coal Gasification coupled with Carbon Capture and Storage (UCG-CCS) remains: the quantification of CO 2 storage capacity in the gasified voids formed by UCG. This uncertainty has hindered the theoretical foundation necessary for site selection and large-scale deployment of UCG-CCS. To address this, the movement and deformation mechanisms of overburden disturbed by UCG are analyzed to elucidate the formation of potential CO 2 storage spaces. A novel quantitative evaluation model for CO 2 storage potential is developed based on the dynamic evolution of overburden failure. The influence of key geological and engineering parameters on storage capacity is revealed. Applied to the Ulanqab UCG pilot site-covering an area of only 0.01088 km²-the gasified voids were shown to accommodate up to 12,010 tonnes of supercritical CO 2 . The research provides a scientific basis for the site selection and feasibility evaluation of UCG-CCS projects. • Reveals the genesis of the CO₂ storage space post-UCG. • A quantitative evaluation model of UCG-CCS storage potential was constructed. • The influence of combustion space area width, mining thickness and bulking coefficient on storage space is clarified.