Underground CO2 Storage: a general overview

Global climate change entails big changes - such as rising ocean levels, due to which some countries may remain under water, and some, on the contrary, will feel a shortage of water, air pollution will lead to an increase in the number of diseases and deaths, the intensity of forest fires, strong hurricanes can negative effect to natural CO2 adsorbers, pollution of the oceans will lead to the death of marine animals, one of the ways to reduce these risks is to capture carbon dioxide, transport it storage facilities and safely store it underground. Carbon dioxide capture and storage (CCS) represents a critical technology for climate change mitigation, with underground geological storage being the most technically mature and widely researched approach. This thesis provides a comprehensive analysis of underground CO2 storage projects worldwide, examining the latest technical literature, technological practices, and regulatory considerations surrounding geological safe sequestration. The research focuses on literature revision, dataset definition, and analysis of existing 20 underground CO2 projects to provide a global overview of CO2 storage implementation and to find the ones with the best properties and technological parameters, which suits for the safe, reliable and long-term CO2 underground storage. The study investigates various storage mechanisms including structural, residual, solubility, and mineral trapping, analyzing their effectiveness across different geological formations. Through examination of operational projects such as Sleipner (Norway), Weyburn-Midale (Canada), and In Salah (Algeria), this work evaluates the thermodynamic properties of CO2 under subsurface conditions, rock-fluid interactions, and the influence of reservoir heterogeneity on storage performance. Key findings indicate that geological formations possess substantial storage capacity, with global estimates ranging from 1000 GtCO2 to over 10,000 GtCO2. However, operational challenges including site characterization, monitoring requirements, and public acceptance continue to limit widespread deployment. The analysis of 20 major storage projects reveals significant variations in storage efficiency, injection rates, and monitoring approaches, with success factors primarily dependent on geological characteristics, regulatory frameworks, and stakeholder engagement. This master thesis contributes to the understanding of underground CO2 storage by providing a systematic evaluation of project parameters and performance metrics, offering insights for future storage site selection and operation optimization.