Geomechanical stability for hydrate-based CO2 sequestration in marine sediments: A comprehensive review

Abstract

Hydrate-based CO₂ sequestration (HBCS) in marine sediments presents a promising strategy for long-term carbon storage, capitalizing on the thermodynamic stability of CO₂ hydrates under seafloor conditions. While the phase behavior and formation mechanisms of CO₂ hydrates have been extensively investigated, the geomechanical stability of hydrate reformation during and after CO₂ injection remains insufficiently explored, with direct implications for safety, efficiency, and scalability. This review synthesizes current knowledge on HBCS across three key offshore geological settings: sub-seafloor formations, natural gas hydrate reservoirs, and depleted oil/gas fields. We identify major gaps, including (i) limited experimental data on the mechanical properties of pure and mixed CO₂ hydrates and their comparison with methane hydrates, (ii) absence of validated constitutive models linking hydrate saturation to sediment mechanics, and (iii) unverified assumptions in numerical models regarding hydrate-induced stiffness gains. We conclude that advancing HBCS requires targeted laboratory studies, development of robust mechanical models, and integration of real-time monitoring in field trials. Addressing these priorities will be essential for safe, reliable, and scalable offshore CO₂ storage.