Earth Science Frontiers ›› 2020, Vol. 27 ›› Issue (1): 134-151.DOI: 10.13745/j.esf.2020.1.15

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Evaluation of geological conditions for the development of deep geothermal energy in China

PANG Zhonghe1,2,3(), LUO Ji1,2,3, CHENG Yuanzhi1,2,3, DUAN Zhongfeng4, TIAN Jiao1,2,3, KONG Yanlong1,2,3, LI Yiman1,2,3, HU Shengbiao1,2,3, WANG Jiyang1,2,3   

  1. 1. Institute of Geology and Geophysics, Chinese Academy of Sciences; Key Laboratory of Shale Gas and Geoengineering, Chinese Academy of Science, Beijing 100029, China
    2. Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029, China
    3. University of Chinese Academy of Sciences, Beijing 100049, China
    4. School of Geosciences, China University of Petroleum (East China), Qingdao 266580, China
  • Received:2019-03-29 Revised:2019-10-09 Online:2020-01-20 Published:2020-01-20

Abstract:

Deep geothermal energy refers to geothermal energy that lies deeper than 3000 meters below Earth’s surface. China is rich in deep geothermal energy, but how favorable are the exploitation conditions? Based on the principle of geothermal geology, in association with rock mechanics, we put forward an indicator system for evaluating the conditions of deep geothermal energy exploitation. We first assign values to each indicator using the expert scoring method; then we apply the principle of fuzzy mathematics to obtain a single value so as to assess the exploitation feasibility. This method considers the safety aspect of enhanced geothermal system (EGS) technology in the development of deep geothermal energy. It advocates adopting the concept of “soft stimulation”, different from the “rigid stimulation” which may induce earthquakes and other key factors not conducive to the healthy development of geothermal energy industry. It also emphasizes the reservoir properties and geophysical fields, expanding and supplementing the previous evaluation results. The established new method is more suitable for the actual geothermal geological conditions, i.e., tectonics dominant geothermal distribution in China. In other words, geothermal energy distribution is closely related to tectonic activities, the stress is relatively high, the crust is generally active with frequent earthquake events. This method makes full use of expert knowledge, adds the role of fuzzy mathematical comprehensive evaluation, and makes the quantitative results easy to compare and use. Therefore, this method is expected to better support decision-making. Based on the new assessment method and existing deep geothermal research and geothermal exploration results, we attempted to make a preliminary assessment of the geological conditions of deep geothermal energy development in nine regions of mainland China, including the north-south geothermal zones in Tibet, the volcanic geothermal regions in western Yunnan Province, the central and eastern regions of Qinghai Province, Northeast and North China, and other regions. We revealed quantitative differences of regional geological conditions for geothermal exploitation, showing that continental China has complex geological conditions, often unfavorable to deep geothermal energy development.

Key words: hot dry rock, deep geothermal energy, geological conditions, evaluation indicator system, fuzzy mathematics, continental China

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