Establishing the geochemical baseline of the CMC FieldResearch Station, Alberta, Canada, prior to CO₂ injection andresolving the source and fate of natural CO₂ in the Morecambe and Rhyl Fields, East Irish Sea Basin, UK

Carbon capture and storage (CCS) is an industrial scale, cost-effective mitigation strategy to reduce anthropogenic CO₂ from entering the atmosphere. Successful deployment of CCS is critically dependent on the safe and secure storage of CO₂ injected into the subsurface for storage. Geochemical monitoring and modelling are an important tool in tracking the migration and fate of injected CO₂ throughout the entire life cycle of a CCS project, from baseline to post-closure. In this thesis, a wide range of geochemical tools are utilised to understand the geochemical baseline of the CMC Field Research Station, Alberta, Canada prior to CO₂ injection, and to identify the source and potential trapping mechanism of CO₂ residing within the Morecombe and Rhyl Fields within the East Irish Sea Basin. The CMC Research Institutes Field Research Station (FRS) is a purpose built test site for developing and demonstrating the monitoring of subsurface fluids following subsurface CO₂ injection. This thesis presents the first multi-well gas and groundwater characterisation of the geochemical baseline of the site. The work highlights that gases sampled from a range of depths exhibit low CO₂ concentrations, and that biogenic methane occurs pervasively in the shallow (