The importance of regional geological mapping in CO₂ storage site characterization: Examples from the IEA Weyburn CO₂ monitoring and storage project

Regional mapping is an essential component to determining the suitability of potential sites for geological storage of CO₂. Within the Weyburn Project, regional mapping established the distribution of primary seals and the lateral continuity of reservoir equivalent strata, and provided the basis for studying the bounding conditions affecting the long-term storage of CO₂. The resulting stratigraphic framework was used to develop a high-resolution hydrostratigraphy needed in investigating the fluid-flow regime around the Weyburn reservoir. In addition, isopach and structure maps and the relationships among different strata levels were used to assess and identify processes such as salt dissolution, erosion and tectonism, and their potential impact on the storage site. Whereas none of these processes has been observed to have compromised the Weyburn reservoir, they have affected potential reservoir strata elsewhere in the larger study region. The stratigraphic data in combination with other geoscience information helped to constrain the spatial extent of the System Model used in risk and performance assessment.