Optimizing CO2 storage and CH4 recovery: An integrated model of geophysical trapping dynamics in shale nanopores

• CCS is vital for reducing CO 2 emissions and meeting 2050 Net-Zero goals. • Study investigates CGS in shale to capture CO 2 and enhance CH 4 recovery. • The current numerical model explores gas transport and competitive adsorption in shale nanopores. • Models updated with multi-component isotherms to predict shale gas behavior. • Post-stimulated shale for CO 2 storage cuts CO 2 and boosts CH 4 desorption. Carbon geological storage (CGS) plays a pivotal role in curbing Carbon Dioxide (CO 2 ) emissions and achieving the global 2050 Net-Zero targets. This study presents an innovative approach by integrating CGS with Methane (CH 4 ) production in shale gas formations, offering a dual benefit of efficient CO 2 storage while enhancing CH 4 recovery from previously trapped reserves. An in-house sophisticated MATLAB code has been utilized in this research to further delve and unlock the geophysical trapping dynamics within both organic and inorganic shale nanoporous systems. Key mechanisms, such Knudsen diffusion, molecular and surface diffusion, as well as viscous and slip flow, are rigorously analyzed and coupled with adsorption–desorption dynamics using the BET isotherm equation. The findings reveal that enhanced CO 2 adsorption in high organic content shales is most favorable under high-pressure and low-temperature conditions, where CO 2 outcompetes CH 4 for adsorption sites, revealing a pronounced adsorption selectivity in favor of CO 2 . This study further identifies optimal conditions for maximizing CO 2 sequestration while ensuring significant CH 4 recovery. The strategic utilization of post-stimulated shale reservoirs for CO 2 storage presents a powerful opportunity: not only does it contribute to climate change mitigation, but it also promotes CH 4 recovery via desorption by optimizing CO 2 injection strategies. Understanding the geophysical dynamic mechanisms highlighted in this research during CO 2 injection is critical for unlocking the full potential of this approach, making it a promising solution for both carbon management and energy production.