A comprehensive review of CO₂ subsurface storage: Integrity, safety, and economic viability

Anthropogenic emissions reached 37.4 Gt/a in 2023, intensifying the need for effective carbon storage in subsurface formations to mitigate global warming. Carbon Capture and Storage (CCS) has emerged as a viable solution, with over 43 operational sites worldwide and projections for more than 840 projects by 2040, potentially storing 2225 Mt CO₂ annually. This review provides a comprehensive analysis of CCS technologies, focusing on the integrity, safety, and economic viability of storage sites, which are crucial for long-term success. It identifies knowledge gaps in existing research, revealing that most studies address specific aspects of CCS but lack integrated approaches combining data, technologies, risks, and economic assessments. Some studies emphasize numerical modeling and fault reactivation risks but overlook issues such as cement degradation and casing corrosion, which are critical to preventing wellbore leakage. Others explore CO₂-rock interactions without considering cement integrity or focus on cement degradation without accounting for other field-scale risks. This review bridges these gaps by examining failures across wellbores, reservoirs, and caprocks, including cement integrity, casing corrosion, uplifting, fault activation, and seismicity due to injection. It also covers numerical modeling, experimental work, and monitoring techniques to ensure CCS integrity. Additionally, this review assesses economic risks to build confidence in CCS deployment, offering a comprehensive framework to ensure secure and long-term CO₂ storage in subsurface formations.