TY  - JOUR
AU  - Deng, Bozhi
AU  - Jiao, Bingyang
AU  - Nie, Baisheng
AU  - Jiang, Changbao
AU  - Li, Minghui
AU  - Zhao, Yumeng
PY  - 2025
TI  - Evolution of microstructural damage in coal under supercritical CO2-water exposure: A multi-scale study incorporating the indentation size effect
JO  - Advances in Geo-Energy Research
SN  - 2207-9963
SP  - 212
EP  - 225
VL  - 17
IS  - 3
AB  - CO2 sequestration in coal seams represents an effective strategy for mitigating CO2 emissions. However, the complicated interaction of CO2-water-coal at the micro-scale may compromise the structural integrity and mechanical strength of coal, thereby adversely impacting the efficacy and safety of CO2 sequestration in coal seams. This study introduces a novel indentation testing method that reveals the scale-dependent evolution mechanisms of coal microstructures, enabling the accurate and reliable quantification level of degradation in the micromechanical properties caused by supercritical CO2-water-coal interactions. Using this method, the extent of mechanical degradation in three types of coal microstructures could be accurately evaluated under supercritical CO2-water-coal interaction. The pure organic matrix exhibited remarkable stability under all fluid treatments, with minor changes in microstructure feature and a mechanical property reduction of less than 25%. In contrast, the mineral structures were significantly altered by treatment with fluid mixed with supercritical CO2 and brine, with erosion depths and mechanical property reductions reaching 1.6 µm and 80% in granular structures, and 6.4 µm and 90% in banded structures. However, in the absence of brine or supercritical CO2, the erosion depths and mechanical property reductions of fusinite were limited.
UR  - https://doi.org/10.46690/ager.2025.09.04
DO  - 10.46690/ager.2025.09.04