ISSN 1000-3665 CN 11-2202/P

    阳高—天镇地区高温地热系统形成机制及资源开发前景研究

    A study of the formation mechanism and resource development prospect of the high-temperature geothermal system in the Yanggao-Tianzhen area

    • 摘要: “双碳”背景下,山西省持续深入推进清洁能源发展,2020年3月在大同天镇县水桶寺村附近探获高温高压地热流体。为探究大同阳高—天镇地区高温地热系统及成因机制,选择阳高孤山村—平山村一带20 km2的范围作为重点研究区,采用地质调查、地球物理、钻探、测井等手段查明研究区地热赋存条件和规律。研究结果表明:(1)阳高—天镇地区的地热资源主要赋存于太古界变质岩及断裂带含水岩组中,直接热源可能为中上地壳未冷却的岩浆囊,盖层为第四系堆积物、新近系和古近系砂砾石层。(2)该地区高温地热系统为对流、传导型地热系统:一方面大气降水、地表水经孔隙渗透作用及断层裂隙通道下渗至热储位置受热形成热水,随后沿断裂通道对流上升至浅地表出露成温泉;另一方面新生代以来持续的伸展拉张环境,导致软流圈上涌,上地幔部分熔融形成的基性玄武岩浆经深部断裂通道上升至中上地壳形成多个岩浆囊,热量通过断裂或高热导率值的太古界变质岩传递至浅地表形成地热异常。(3)YG-1井抽水试验结果显示,该地区水热型地热资源以静储量为主,开发利用应考虑采用无干扰换热技术。综合分析区域地质条件,结合物探、钻探成果,认为该地区深部可能存在干热岩型地热资源,有待进一步查证。

       

      Abstract: Under the background of “dual carbon”, Shanxi Province continues to promote the development of clean energy. In March 2020, high-temperature and high-pressure geothermal fluid was discovered near the Shuitongsi Village in Tianzhen County in Datong. In order to explore the high temperature geothermal system and its genetic mechanism in the Yanggao-Tianzhen area in Datong, an area of 20km2 in the Gushan Village-Pingshan Village of Yanggao County is selected as the key research area. Geological survey, geophysics, drilling, logging and other methods are used to find out the occurrence conditions and rules of geothermal energy in the study area. The results show that (1) the geothermal resources in the Yanggao-Tianzhen area are mainly hosted in the Archean metamorphic rocks and water-bearing formations in fault zones. The direct heat source may be from the uncooled magma chamber in the middle and upper crust, and the caproks are the Quaternary accumulation, Neogene and Paleogene gravel layer. (2) The high-temperature geothermal system in this area is the convection and conduction geothermal system. On the one hand, atmospheric precipitation and surface water may infiltrate into the geothermal reservoir through pores and fault-fissure channels to form hot water. Then, it ascends to the shallow surface by convection along the fault-channels and forms a hot spring. On the other hand, the continuous extensional environment since the Cenozoic has led to the upwelling of the asthenosphere. The basaltic magma formed by partial melting of the upper mantle rises to the middle and upper crust through deep fault channels to form multiple magma pockets. Heat is transferred to the shallow surface through faults or Archean metamorphic rocks with high thermal conductivity to form geothermal anomalies. (3) The pumping test results of the YG-1 well show that, hydrothermal geothermal resources in this area are mainly static reserves, and non-interference heat exchange technology should be considered for the development and utilization.Through a comprehensive analysis of regional geological conditions, combined with geophysical prospecting and drilling results, it is believed that there may be dry-hot rock geothermal resources in the deep part of the region, which needs further investigation.

       

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