A Review of Research Progress and Future Prospects of CO₂ Sequestration and Enhanced Coalbed Methane Recovery in Deep Coal Seams

Global decarbonization imperatives have propelled CO₂-enhanced coal-bed methane (CO₂-ECBM) to the forefront of technologies that couple energy recovery with carbon sequestration. This paper systematically reviews recent advances in CO₂-ECBM research across scientific, engineering, and policy-economic dimensions. CO₂ is sequestered in coal seams via a synergistic suite of processes: adsorption, capillary trapping, structural trapping, dissolution trapping, and mineral trapping. These complementary sequestration mechanisms collectively promote long-term, stable storage. CO₂-ECBM technology not only effectively increases coalbed methane recovery but also offers substantial sequestration potential and favorable geological stability. However, practical applications face challenges such as limited CO₂ injectability in coal seams, inadequate safety assessments, and economic feasibility concerns, including high technical costs and carbon price volatility. While engineering practices globally have demonstrated the feasibility of CO₂-ECBM technology for both enhancing coalbed methane production and achieving CO₂ sequestration, further technological optimization and policy support are needed. Future research should focus on regional adaptability, efficient fracturing techniques for permeability enhancement, multi-phase and multi-scale migration mechanisms, and the development of intelligent monitoring and early-warning systems.Concurrently, it is imperative to strengthen technology integration and policy support to accelerate the commercialization and scaling of CO₂-ECBM technology. These initiatives are critical for underpinning global efforts toward achieving carbon neutrality goals.