A review of carbon storage in saline aquifers: Key obstacles and solutions

Carbon capture and storage (CCS) in saline aquifers represents a critical solution for reducing atmospheric CO2 concentrations and mitigating climate change. Despite its promise, the implementation of CCS faces numerous challenges. Our findings are organized into four main categories: geological, well-related, planning, and operational challenges. We highlight the issue of gravity override, which can reduce sweep efficiency as CO2 migrates vertically, potentially compromising storage capacity. Caprock integrity is another focal point, as any breach could result in CO2 leakage, threatening long-term storage security. We also examine the delicate balance between maximizing well injectivity and maintaining caprock integrity under high-pressure conditions. Well- related challenges, particularly the risk of corrosion in injection and monitoring wells due to subsurface conditions, are also addressed, emphasizing their potential to jeopardize CO2 containment. From a planning perspective, the study underscores the importance of accurate storage capacity estimates for effective project planning and risk management. This study examines economic and environmental factors, including the influence of permeability on storage costs and the impact of CO2-induced acidity on ecosystems. Finally, we propose a comprehensive monitoring strategy that integrates both downhole and surface-based tools, offering a more robust approach compared to conventional methods. By addressing these multifaceted challenges, this study provides practical insights to inform best practices and innovations in CO2 storage.