Occurrence Law And Resource Evaluation Of Geothermal Resources In Huixian Huayu Geothermal Area

Based on the geothermal Resources Investigation of Qingyangkou Fault Zone（Hebi--Huixian）in Henan Province,the 2019 provincial financial geological exploration project of Henan Province,this paper analyzes the heat storage characteristics,geothermal field characteristics and hydrogeochemical characteristics of geothermal resources in The Huayu geothermal area,and evaluates the quality of geothermal resources and geothermal fluids.It provides scientific basis for the exploitation and rational utilization of geothermal resources.The Huayu geothermal area is a tectonic fault-convection deep-circulation geothermal system,which is distributed along the Huayu fault in a zonal pattern with a thermal storage area of 14061726.5m².Its thermal storage units are divided into Ordovician limestone thermal reservoirs,Sinian quartz sandstone thermal reservoirs and Archaean Gneisses thermal reservoirs,with average temperatures of 55.3℃,93.4℃and 106.7℃,respectively.According to the hydrogeochemical characteristics of the study area,the geochemical type of geothermal water in The Huayu geothermal area is Cl·SO₄—Na type.Based on the calculation results of geothermal temperature scale,silicon-enthalpy diagram and silicon-enthalpy mixing model,the mixing ratios of hot and cold water in RJ1,RJ2 and RJ3 are 71%,80%and 55%,respectively.The deep heat storage temperature is 158.8℃,and the circulation depth of geothermal water is about 4823.33m.Based on the stable isotope analysis of hydrogen and oxygen,it is concluded that the recharge of The Huayu geothermal area is from meteoric water,and the recharge elevation is between 424.41m and 948.91m,indicating that the groundwater recharge area of The Huayu geothermal area is mainly in the northern mountainous area.According to the carbon isotope characteristics,the geothermal water age is about 18902a.Heat storage and numerical methods were used to calculate and evaluate the geothermal resources in The Huayu geothermal area.The geothermal resources reserves are 1.75×10¹⁸J,equivalent to 5.98×10⁷t of standard coal.The exploitable geothermal resources are 1.31×10¹⁷J,equivalent to 4.47×10⁶t of standard coal.The total volume of stored hot water is 1.86×10⁸m³,and the recoverable amount of geothermal water is estimated to be 5.40×10⁴m³/a and the recoverable heat of geothermal water is 9.57×10¹²J/a,equivalent to 3.27×10²t/a of standard coal,according to the mining coefficient method（mining years are 100 years）.The thermal power of the geothermal field is 3.09×10²k W,which is a small-scale geothermal field.Based on the water quality test results of three geothermal Wells in The Huayu geothermal area,geothermal fluids in the heat storage area were evaluated for physiotherapy thermal mineral water,drinking natural mineral water,drinking water,agricultural irrigation water,fishery water,corrosion of geothermal fluids and corrosion of geothermal fluids.The results showed that geothermal water in Huayu geothermal area was suitable for physiotherapy mineral water.However,due to the excessive fluoride ion in geothermal water,it is not suitable for direct use as drinking natural mineral water,drinking water,agricultural irrigation water and fishery water.In addition,the geothermal water in Huayu geothermal area is highly corrosive,so corrosion prevention should be considered in the development and utilization of well pipes and water pipelines.