Earth Science Frontiers ›› 2024, Vol. 31 ›› Issue (6): 252-260.DOI: 10.13745/j.esf.sf.2024.7.23

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Fault slip tendency and induced-earthquake risks in hot dry rock development: A case study in the Tangshan Matouying HDR site

SHANGGUAN Shuantong1(), TIAN Lanlan1, PAN Miaomiao1, YANG Fengliang1, YUE Gaofan2,3,*(), SU Ye1, QI Xiaofei1   

  1. 1. The Second Geological Team of Hebei Coal Geology Bureau (Hebei Hot Dry Rock Research Center), Xingtai 054001, China
    2. Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, China
    3. Technological Innovation Center of Geothermal & Hot Dry Rock Exploration and Development, Ministry of Natural Resources, Shijiazhuang 050061, China
  • Received:2024-02-21 Revised:2024-05-10 Online:2024-11-25 Published:2024-11-25

Abstract:

Induced earthquakes are one of the major problems in hot dry rock (HDR) development. Fault slip and fluid overpressure are the two main causes of large induced earthquakes, whilst local geological conditions affect the characteristics of the earthquakes. This study selects the Matouying HDR site was selected as the study area. The seismology, tectonics, and geothermal characteristics of the HDR site were analyzed in great detail. A THM multifield coupling numerical model was established, taking into account the impact of geostresses and multiple faults. The fault stability during the HDR development was evaluated based on the calculated slip tendency of the faults, and the maximum magnitude of injection-induced slip was estimated based on the calculated volume of disturbed rocks. According to the results, during the 10-year HDR development, pore pressure on the faults changed by no more than 0.8 MPa, causing no significant changes in the effective stress on faults. The slip tendency of the faults during exploration was far lower than the slip warning threshold, and the injection process was safe. Two models for calculating seismic moment were optimized, and the calculated maximum magnitude of induced earthquakes by a 10-year loop was between 2.0—2.1. Results from this study can not only support safe development of HDR at the Matouying HDR site, but also help to gain deeper understanding of the geodynamic processes affected by engineering activities.

Key words: hot dry rock, induced earthquakes, fault slip trend, maximum magnitude, multi-field coupling

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