As noted in our previous post, the frequency of events, and hence the overall risk profile, will change during the life of a SCS project. The changes depend largely on the operations that are underway during each stage. This general model leads to the concept of Peak Risk depicted in the Figure below.
In the Identification stage, locations are selected that have a strong potential for safe and commercial storage. In the subsequent Appraisal stage, reservoir parameters are refined and reservoir injectivity is tested. Project risks include failing to confirm a sufficient pore volume or achieve some minimum injection rate. The impact of a failure in these two stages would be a loss of time and money limited to the participating parties.
During the Injection stage, the entire project from transport to injection, pressure management, and CO2 migration will be simultaneously tested. This is likely to create the greatest number of events and potential hazards. Project risk would likely decrease in the post-injection Monitoring stage as the plume stabilizes and becomes stationary. The impact of a failure in these two stages could impact non-participating parties via CO2 leakage, CO2 plume migration, induced seismicity, etc.
The timing and duration of any Peak Risk period depends on each specific project, so the shape and amplitude of the curve will vary. Because the time period from initial evaluation to the CO2 plume becoming geologically stable can be hundreds to thousands of years, a quantitative assessment is needed to understand the risk profile for each specific project and associated stage. Various qualitative descriptions of risk as a function of time have been published for SCS projects, but in our view are insufficient because they lack a quantitative assessment of the changing risks with time.
