A Critical Review of ScCO2-enhanced Gas Recovery and Geologic Storage in Shale Reservoirs

Carbon dioxide-enhanced shale gas recovery (CO2-ESGR) has been identified as a promising technology for carbon emission mitigation as well as for its additional benefits regarding energy recovery. This review aims to consolidate comprehensive and contemporary findings concerning SC-CO2 injection in shale formations. These findings indicate that CO2 has a significantly greater adsorption capacity in shale than CH4. Moreover, shale reservoirs possess the potential for large-scale carbon sequestration. Additionally, SC-CO2 injection can lead to various CO2 uptake-induced physicochemical reservoir rock alterations reflected by multimechanism–adsorption–dissolution–precipitation–transportation–wettability changes. This coupling mechanism can suppress the mechanical properties of shale, causing matrix swelling and crack sprouting, which in turn affects its storage capacity.