Wellbore leakage risk management in CO2 geological utilization and storage: A review

CO2 geological utilization and storage (CGUS) is an important technology to achieve a deep cut of global CO2 emissions. CO2 leakage from the subsurface may impair the performance of CGUS projects, and the CO2 leakage through wellbores is the most common leakage pathway. This paper proposes a workflow for wellbore CO2 leakage risk management, and the workflow consists of the following steps: i) leakage risk identification; ii) leakage risk evaluation; iii) leakage risk monitoring; iv) leakage handling. Representative approaches in each step of the workflow are systematically reviewed. Key challenges of wellbore CO2 leakage risk management include: lack of effective detection and evaluation approaches to tackle the CO2 leakage risk induced by cement failure; lack of low-cost acid resistance alloys and CO2-resistant cement; lack of automated monitoring systems that could enable automated shutdowns of the wellbore whenever certain warning criteria are met.