Hydrogeochemistry and Heat Accumulation of a Mine Geothermal System Controlled by Extensional Faults

Mengwei Qin, Bo Zhang, Kun Yu (), Baoxin Zhang, Zhuting Wang, Guanyu Zhu, Zheng Zhen and Zhehan Sun
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Mengwei Qin: School of Mines, China University of Mining and Technology, Xuzhou 221116, China
Bo Zhang: Institute of Coal Mining and Utilization, Pingdingshan Tianan Coal Mining Co., Ltd., Pingdingshan 467099, China
Kun Yu: School of Mines, China University of Mining and Technology, Xuzhou 221116, China
Baoxin Zhang: School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, China
Zhuting Wang: School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China
Guanyu Zhu: School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, China
Zheng Zhen: School of Mines, China University of Mining and Technology, Xuzhou 221116, China
Zhehan Sun: School of Mines, China University of Mining and Technology, Xuzhou 221116, China

Energies, 2025, vol. 18, issue 10, 1-15

Abstract: Given the high proportion of global fossil energy consumption, the Ordovician karst water in the North China-type coalfield, as a green energy source that harnesses both water and heat, holds significant potential for mitigating environmental issues associated with fossil fuels. In this work, we collected geothermal water samples and conducted borehole temperature measurements at the Xinhu Coal Mine in the Huaibei Coalfield, analyzed the chemical composition of regional geothermal water, elucidated the characteristics of thermal storage, and explored the influence of regional structure on the karst geothermal system in the northern region. The results indicate that the geothermal water chemistry at the Xinhu Coal Mine is of the Na-K-Cl-SO 4 type, with its chemical composition primarily controlled by evaporation and concentration processes. The average temperature of the Ordovician limestone thermal reservoir is 48.2 °C, and the average water circulation depth is 1153 m, suggesting karst geothermal water undergoing deep circulation. The geothermal gradient at the Xinhu Coal Mine ranges from 22 to 33 °C/km, which falls within the normal range for ground-temperature gradients. A notable jump in the geothermal gradient at well G1 suggests a strong hydraulic connection between deep strata within the mine. The heat-accumulation model of the hydrothermal mine geothermal system is influenced by strata, lithology, and fault structures. The distribution of high ground-temperature gradients in the northern region is a result of the combined effects of heat conduction from deep strata and convection of geothermal water. The Ordovician limestone and extensional faults provide a geological foundation for the abundant water and efficient heat conduction of the thermal reservoirs.

Keywords: geothermal water; coal mine; heat accumulation; fault system; hydrogeochemistry (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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