PANG Zhonghe, DUAN Zhongfeng. Heat accumulation model and utilization direction of geothermal resources in coalbearing areas of North China[J]. COAL GEOLOGY & EXPLORATION.
Citation: PANG Zhonghe, DUAN Zhongfeng. Heat accumulation model and utilization direction of geothermal resources in coalbearing areas of North China[J]. COAL GEOLOGY & EXPLORATION.

Heat accumulation model and utilization direction of geothermal resources in coalbearing areas of North China

  • Objective China is a coal-rich country. In the urgent need for energy transition of the coal industry, it is necessary to study the genesis and occurrence of geothermal resources in the coal-bearing areas. The geothermal reserves in the North China coal-bearing areas account for 74.7% of the whole country, which is of the region with the most abundant geothermal resources in China. There are major coal-bearing basins in North China, including: Bohai Bay Basin, Ordos Basin, Qinshui Basin and South North China Basin, etc. The thermal strength gradually decreases from east to west. There are two types of geothermal reservoirs, i.e. Cenozoic sandstone pore type and Cambrian-Ordovician carbonate karst-fractured type. The carbonate karst-fractured geothermal reservoir has higher temperature, larger water yield and is easy to reinject, which will be the priority exploration targets of geothermal resources development in coal-bearing areas. Methods Taking the coal-bearing area in North China as an example, an analysis of the dynamics of the geothermal systems in the region is carried out to address the special geological conditions of the coal-bearing areas. Results and Conclusions Several heat accumulation models are proposed for the coal-bearing area: (1) The combination of coal seams and carbonate rock reservoirs with a conductive heat accumulation mechanism. (2) The later variation of the bedrock elevation with a conductive heat accumulation mechanism. (3) Groundwater circulation in the fault zones with a convective heat accumulation mechanism. (4) Groundwater circulation in the weathered karst zones in the uplifted carbonate bedrock surface with a conductive and convective "dualtrack" heat accumulation mechanism. Numerical models are built for a few case examples to verify these mechanisms. On this basis, it is pointed out that the priority for future exploration and development of the geothermal resources in the deep carbonate reservoir with a sandstone or a loose sediment cover. Geothermal energy is a non-carbon-based energy source that is expected to make significant contributions to the heat supply among the electricity, fuel, and heat demand due to its advantages such as large in quantity, clean, stable and continuous in supply. The overlap in the spatial distribution of geothermal and coal resources in North China makes geothermal development and utilization an effective way for the transition of the coal energy industry into a cleaner one and the realization of carbon neutrality.
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