Cryogenic fracturing of coal with LN2 treatment: A sustainable approach for enhancing coalbed methane extraction in water-scarce regions
Longinos S.N. Begaliyev D. Asif M. Tuleugaliyev M.
October 2025Elsevier B.V.
Gas Science and Engineering
2025#142
Alteration of the pore space in coal fractured by liquid nitrogen (LN2) significantly influences the coalbed methane (CBM) process to overall porosity, effective permeability, pore rugosity, and adsorption capacity. The impact of LN2 treatment on the pore structures of coal samples from the Karaganda Coal Basin, Kazakhstan, was analyzed to enhance CBM extraction. This study employs Mercury Intrusion Porosimetry (MIP) and Low-Pressure Nitrogen Gas Adsorption (LN2GA) isotherm for analyzing the effects of varying freezing times and freezing-thawing cycles on the pore structure of coal. The maximum nitrogen adsorption capacity (25.02 cc/g) and the total injected mercury volume (0.226 cc/g) in the specimens were positively correlated (R2 = 0.98) with the total freezing time and the number of freezing-thawing cycles. As LN2 freezing time increases, fractal dimensions decrease, indicating a more uniform pore structure. The values drop from D1 = 2.43, D2 = 2.80 (0 min) to D1 = 2.17, D2 = 2.62 (180 min), suggesting reduced roughness and complexity. The peak intrusion volumes increased from 0.185 cm3/g (0 min) to 0.217 cm3/g (180 min), indicating that prolonged freezing expands the coal structure to create additional pores. Ejection efficiency improved from 68.32 % (0 min) to 77.22 % (180 min), reflecting better pore connectivity as the freezing duration increases. This study is paramount in the cryogenic fracturing of coal formation and may be opted against hydraulic fracturing for various industrial applications in water-scare regions.
Fractal characteristics , Karaganda coal basin , LN2GA , MIP , Pore structure alteration
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School of Mining and Geosciences, Department of Petroleum Engineering, Nazarbayev University, Astana, Kazakhstan
Industrial and Technological Institute, Zhangir Khan University, Uralsk, Kazakhstan
Department of Geotechnical Engineering, Tongji University Shanghai, China
School of Engineering and Digital Sciences, Department of Chemical and Materials Engineering, Nazarbayev University, Astana, Kazakhstan
School of Mining and Geosciences
Industrial and Technological Institute
Department of Geotechnical Engineering
School of Engineering and Digital Sciences
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