Reinjection tracer test on thermal reservoir of metamorphic rock in Xishan area of Taiyuan City

The metamorphic rock geothermal resources in Hekou Town, Xishan area, Taiyuan City belong to the medium-low temperature geothermal field of mountain type, the geothermal water temperature is 40−42 °C, and the hydrochemical type is Cl·SO₄—Na type. At present, the connectivity of the two geothermal wells is not clear. In order to extend the service life of the geothermal field, a reasonable mining and reinjection scheme needs to be proposed. Master the migration characteristics and recharge capacity of geothermal fluid in the study area, so as to explore the causes of thermal breakthrough. In this study, the GJDR-1 geothermal well was used as a recharge well and a KI tracer delivery well to monitor the water level and recharge water temperature. It is necessary to carry out reinjection tracer test on metamorphic rock thermal reservoir. The GJ-WEMC geothermal well is used as a mining well and a tracer observation well to monitor the tracer composition and water temperature. According to the existing geothermal geological data combined with the results of this tracer test, the protection radius of the geothermal well is calculated. The results show that there is a hydraulic connection between the production and reinjection wells. Under natural conditions, the recharge capacity of metamorphic rock thermal reservoir in this area is 9.2 m³/h, and the thermal breakthrough phenomenon will occur with the well spacing of 488 m, and the well spacing should be more than 1140m. The well spacing, recharge temperature and recharge amount will affect the thermal breakthrough.