Abstract

Expertise in the science and best practices of injecting CO₂ for permanent storage has been growing for about 30 years. Many techniques are mature and ready to support the commitments of governments and businesses globally. Diverse facilities have combustion or process engineering activities that now produce large volumes of CO₂ and release it to atmosphere; mitigation is needed. Carbon capture and storage (CCS) allows capturing CO₂ at these point sources and injecting the captured CO₂ into porous sedimentary rocks beneath and effectively isolated from groundwater resources for permanent storage.

Storage of CO₂ is built on geotechnical approaches used for over a century for hydrocarbon and groundwater production, brine and other waste fluid injection, and injection of CO₂ and other fluids for secondary and tertiary recovery. However, injection of CO₂ for long-term storage requires several new ways of using geotechnical skills. New skills have been developed and tested in a series of studies and tests described, herein. For example, the DOE-funded Frio test in Liberty County, TX, and the SECARB early test at Cranfield Field, MS, assessed multiple methods of documenting multiphase flow using geophysical and geochemical tools and developed new approaches for environmental assurance monitoring in soils and groundwater. Studies at West Ranch and Hastings Fields, TX, have tested methods for assuring retention in areas with dense well penetrations. These US-based onshore projects are linked to dozens of international projects and to newly developing projects both onshore and offshore. Together, this experience builds confidence in methods for selection of geologic sites that will accept and retain large volumes of CO₂. In addition, methods for documenting that the modeling assumptions made during site selection are validated by monitoring have been robustly tested. We document progress and highlight areas where future improvement will add value.