Workflows and recommendations for evaluating containment risk of geological carbon sequestration sites: examples from the Inner Moray Firth Basin

This study presents workflows for evaluating containment risk for geological carbon sequestration at the early stages of site investigation, applied to examples from the Inner Moray Firth (IMF) Basin, UK Continental Shelf. The IMF represents an excellent natural laboratory due to the proliferation of public domain subsurface data, a variety of potential storage opportunities and easily accessible age-equivalent outcrops. We document three distinct styles of containment (depleted fields; brine-filled traps and saline aquifers), exhibited through a series of case studies throughout the basin. The risk and uncertainty associated with each of these containment style case studies are articulated through a series of risk matrices, commonly used in traditional petroleum subsurface workflows. Within each of these containment styles, three distinct phases are key for the delivery of an effective carbon sequestration site: the injection phase (decades), the migration phase (centuries) and finally long-term retention (over thousands of years). Each style and flow phase has distinct derisking attributes and workflows and there are generic implications for screening containment risk for basins globally. The workflows aid in rapidly prioritizing a portfolio of investment opportunities and, more importantly, identify key uncertainties and data acquisition and technical evaluations that can derisk uncertainty prior to investment decisions.