Revisiting the Utsira Saline Aquifer CO2 Storage Resources Using the SRMS Classification Framework

Abstract

One major challenge for the CCS industry is to understand if CO2 geological storage can be implemented at the scale needed to address the climate change issue. Indeed, a high variability in CO2 storage resource estimates is encountered in the literature. To address this variability and provide more confidence in global and regional resource assessments, the Storage Resource Management System (SRMS) was developed by the Society of Petroleum Engineers (SPE). The SRMS provides guidelines on how to classify CO2 storage resources using both an uncertainty scale and a maturity scale. We apply the SRMS to the Utsira formation, as Utsira has been widely studied for CO2 storage and since the Sleipner operation, injecting up to 1 Mt of CO2 per year since 1996, provides a degree of validation. The range of the storage resource estimates is primarily assessed by evaluating different storage concepts: storage in structural traps, through residual trapping, or the effects of a limiting value for overpressure. The major uncertainties attached to these concepts are well known and further work is needed to incorporate resource estimates into an uncertainty framework in order to understand the spread in these estimates and to identify the best appraisal strategy to narrow that range.