This report is about the IEAGHG Weyburn-Midale CO2 Monitoring and Storage Project, which is a top-level research program designed to investigate the effects of CO2 injection and storage in the oil reservoirs of southeastern Saskatchewan, Canada. The project, which was completed in two phases between 2000 and 2012, investigated large-scale CO2 injection, monitoring, and modeling in deep geological formations. The first phase of the project was published in 2005, and the second phase was published in the form of 'Best Practices for Validating CO2 Geological Storage: Observations and Guidance from the IEAGHG Weyburn-Midale CO2 Monitoring and Storage Project' in 2012.