Experimental study and finite element simulations for LN2 fracturing in coal from Karaganda Basin
Longinos S.N. Konysbekov A. Skrzypacz P.
March 2025Springer Science and Business Media Deutschland GmbH
Bulletin of Engineering Geology and the Environment
2025#84Issue 3
This study looked at the effectiveness of liquid nitrogen (LN2) in two distinct coal fracturing processes, freezing time (FT) and freezing–thawing cycle (FTC), for specimens that were saturated with water. The effectiveness of cryogenic treatment for coal rocks was compared using uniaxial compressive strength (UCS) and Brazilian tests. The results indicated in both USC and Brazilian tests, FTC experiments showed better results compared to FT experiments, leading to the conclusion that it may be possible to attain a higher desired permeability improvement by using more LN2 injections in real-world LN2 fracturing applications. In brittleness analysis, FT experiments showed higher values than FTC in the B21, B22, B24, and B25 indexes, while FTC experiments showed higher values in the B19 and B20 indexes. A scanning electron microscope (SEM) was used for fracture evolution analysis. Further, numerical simulations detailed the stress distribution patterns within coal samples under cryogenic treatment, utilizing von Mises stress analysis to compare the progression over time. The simulation results, particularly at peak stress periods, strongly correlate with experimental data, validating the models effectiveness. These findings offer substantial evidence for the feasibility of LN2-based treatments in enhancing coal bed permeability, with implications for improving the efficiency and safety of coal extraction processes.
Brazilian test , Coal fracturing , Compression test , Finite Element Simulations , Liquid nitrogen
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School of Mining and Geosciences, Department of Petroleum Engineering, Nazarbayev University, Astana, Kazakhstan
School of Engineering and Digital Sciences, Department of Civil and Environmental Engineering, Nazarbayev University, Astana, Kazakhstan
School of Sciences and Humanities, Department of Mathematics, Nazarbayev University, Astana, Kazakhstan
School of Mining and Geosciences
School of Engineering and Digital Sciences
School of Sciences and Humanities
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