Pore structure alteration in heated granite after LN2 treatment: An experimental study for the enhanced geothermal energy extraction


Longinos S.N. Asif M. Mathews G.
July 2025Elsevier Ltd

Geothermics
2025#130

The cryogenic fracturing of two granite samples was performed in this paper for the pore characterization to enhance geothermal energy extraction. The samples were heated initially to 600 °C and subsequently analyzed for liquid nitrogen (LN2) treatment for multiple freezing and freezing-thawing cycles. The mercury intrusion and low-pressure nitrogen adsorption reveal a significant alternation in the pore characteristics of granite samples. The nitrogen adsorption capacity increases from 1.08 cc/g to 1.52 cc/g after LN2 treatment. This study also examines a significant increase in pore volume as pore volume increases by 135–152 %. Furthermore, the XRD analysis of the samples was executed to study the microscopic effect of the minerals in the granite samples. The LN₂ treatment of the sample enhances pore connectivity, as evidenced by the XRD analysis of sample 1, which reveals a high feldspar and biotite content. In contrast, sample 2 experiences limited fracturing effects due to its high quartz content. Therefore, the cryogenic fracturing of heated granite samples demonstrates significant potential for investigating pore structure modifications to improve geothermal energy recovery. This study establishes a fundamental framework for advancing geothermal energy extraction and contributes to the development of renewable energy in Kazakhstan.

Geothermal energy Kazakhstan , Granite , LN2 fracturing , Pore structure

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School of Mining and Geosciences, Petroleum Engineering Department, Nazarbayev University, Astana, Kazakhstan
Department of Geotechnical Engineering, Tongji University, Shanghai, China
School of Mining and Geosciences, Geology Department, Nazarbayev University, Astana, Kazakhstan

School of Mining and Geosciences
Department of Geotechnical Engineering
School of Mining and Geosciences

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