Qualitative risk assessment for using a mature oil field as a pilot experiment of CO2 geological storage in Brazil

Abstract

Carbon geological storage (CGS) projects are designed to securely store carbon dioxide (CO2) for thousands of years. Because of this, there are several studies to evaluate the potential risks of long-term storage of CO2 in geological formations. This paper presents a new method for the qualitative risk assessment of CGS: the risk assessment of stored CO2 (RA-CO2) method. It consists of the systematic and structured identification of CO2 release risk scenarios arising from: seal, well, and fault and fracture zones. The uncertainties associated to each mapped risk scenario and the risks are qualitatively evaluated using the RA-CO2 method. The characteristics of the RA-CO2 method enable a comprehensive understanding of the underground evolution and future behaviour of the CO2 in various time scales and their influence on safety. For future studies, the validation of the proposed RA-CO2 method using a real case study is recommended.