CO 2 geological storage: Contribution of geology to “global warming” mitigation

Abstract

Due to growing concerns about increasing atmospheric CO2 con- centrations, urgent development of carbon capture and storage (CCS) technology is necessary. The 1996 Protocol to the London Con- vention became effective in 2006, and prohibited CO2 storage in deep ocean masses. This means that the only viable option for CCS is stor- age in geological formations. One option for geological CCS is in de- pleted oil or gas reservoirs, which have closure structures that could retain oil or gas over geological time scales, and are relatively easy to with technologies developed for enhanced oil and gas recovery. Such oil or gas reservoirs suitable for CCS are, however, scarce around the islands of Japan. In contrast, storage in deep saline aquifers may be an option due to their large capacity. This type of storage was first attempted in the Sleipner area of the North Sea. The aquifer storage option is particularly promising for CCS in Japan, as appropriate geological formations are common around the islands of Japan. Off- shore saline aquifers with a large storage capacity might be particu- larly suitable for large emission sources, such as thermal electricity generation plants and steel refineries located in coastal regions. We review several important geological case studies of CO2 stor- age, including the Iwanohara Pilot Plant, which is the first onshore example of geological CCS. We also briefly present results of a nu- merical simulation study based upon a conceptual CCS model for the coastal aquifers underlying the Tokyo Bay area, and a summary of