Time-evolution of ScCO2-weakened coal integrity: Chemo-hydromechanical coupling and geological sequestration implications

Time-evolution of ScCO2-weakened coal integrity: Chemo-hydromechanical coupling and geological sequestration implications

Geological sequestration of CO2 is critical for deep decarbonization, but the geomechanical stability of coal reservoirs remains a major challenge. This study integrates nanoindentation, XRD/SEM-EDS chemo physical characterization and 4D CT visualization to investigate the time-evolving mechanical d...

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Bibliographic Details
Main Authors: Peng Liu, Jingtao Yang, Baisheng Nie, Ang Liu, Wei Zhao, Hao Xu, Hengyi He
Format: Article
Language:English
Published: Elsevier 2025-06-01
Series:International Journal of Mining Science and Technology
Subjects:
CO2 sequestration
Nanoindentation
Reservoirs stability
Coal mechanics
Online Access:http://www.sciencedirect.com/science/article/pii/S2095268625000837
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Summary:Geological sequestration of CO2 is critical for deep decarbonization, but the geomechanical stability of coal reservoirs remains a major challenge. This study integrates nanoindentation, XRD/SEM-EDS chemo physical characterization and 4D CT visualization to investigate the time-evolving mechanical degradation of bituminous coals with ScCO2 injection. The main results show that 4 d of ScCO2 treatment caused 50.47%–80.99% increase in load–displacement deformation and 26.92%–76.17% increase in creep depth at peak load, accompanied by 55.01%–63.38% loss in elastic modulus and 52.83%–74.81% reduction in hardness. The degradation exhibited biphasic kinetics, characterized by rapid surface-driven weakening (0–2 d), followed by stabilized matrix-scale pore homogenization (2–4 d). ScCO2 preferentially dissolved carbonate minerals (dolomite), driving pore network expansion and interfacial debonding, while silicate minerals resisted dissolution but promoted structural homogenization. These coupled geochemical-mechanical processes reduced the mechanical heterogeneity of the coal and altered its failure modes. The results establish a predictive framework for reservoir stability assessment and provide actionable insights for optimizing CO2 enhanced coalbed methane recovery.
ISSN:2095-2686

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