A review of research progress and future prospects of CO₂ sequestration and enhanced coalbed methane recovery in deep coal seams

With the escalating global demand for carbon emission reduction, CO₂ sequestration and enhanced coal-bed methane (CO₂-ECBM) has attracted widespread international attention due to its distinctive advantages in promoting the synergistic development of energy development and carbon emission reduction. This paper systematically reviewed recent advances in CO₂-ECBM research across scientific, engineering, and policy-economic dimensions. Besides, it elucidated the sequestration mechanisms governed by a synergistic suite of processes, including adsorption trapping, capillary trapping, structural trapping, solubility trapping, and mineral trapping, and further evaluated the technological maturity and economic feasibility of the technology. The results demonstrate that CO₂-ECBM technology not only effectively promotes coalbed methane recovery but also offers substantial sequestration potential and favorable geological stability. Through a comparative analysis on typical demonstration projects conducted worldwide, it is pointed out that practical applications of this technology still face challenges such as poor injectability of coal seams, permeability decline induced by CO₂ injection, insufficient assessment of long-term sequestration safety, and economic feasibility hampered by technical costs and carbon price volatility. Drawing on bibliometric analysis and hotspot evolution mapping, this study outlines the current research landscape and development trajectory, highlighting critical future priorities such as geological suitability evaluation systems for sequestration sites, high-efficiency technologies for coal seam permeability enhancement, multi-field coupled multi-scale CO₂ migration mechanisms, and intelligent monitoring and early warning systems for sequestration stability. 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.