Hydrogeochemical Characteristics Of Mid-deep Geothermal Water In Central And Western Jilin Province

Geothermal energy is a clean,economical and renewable energy source.The rational development of geothermal energy can alleviate energy shortage,protect the environment,and avoid the greenhouse effect caused by the combustion of traditional industrial energy.The central and western regions of Jilin Province span across the western slope area,central depression area and southeastern uplift area of the Songliao Basin,and contain abundant geothermal water resources in sedimentary basins.Geothermal water is the product of complex reactions of geothermal energy,groundwater and mineral phases of rock formations under the conditions of temperature and pressure,and is an information carrier that reflects changes in the geological environment.Systematic analysis of the chemical characteristics of geothermal water in thermal reservoirs,revealing the chemical genetic mechanism of geothermal water,has guiding significance for the rational development of geothermal resources in the central and western regions of Jilin Province and the establishment of an effective clean energy supply.Relying on the geothermal resources survey project in the central and western regions of Jilin Province,this paper discusses the mid-deep geothermal water in the Upper Cretaceous Yaojia Formation and Qingshankou Formation,and the Lower Cretaceous Quantou Formation,Denglouku Formation and Yingchengzi Formation from three aspects.hydrogeochemical characteristics.Firstly,according to the hydrochemical data of 1410 groups of geothermal water samples in the study area,the statistical analysis of geothermal water in the study area in the western slope area,the central depression area and the southeast uplift area TDS and the range,average value and water content of the major components and trace components respectively Chemical types,thereby analyzing the horizontal and vertical distribution characteristics of water chemical components.Then,according to the recharge,runoff and discharge conditions of geothermal water in the basin,six representative simulation paths were selected in the main thermal reservoirs Yaojia Formation,Qingshankou Formation and Quantou Formation to carry out the hydrogeochemical simulation based on the PHREEQC inverse simulation module.,in order to analyze the water-rock interaction in the process of geothermal water runoff in the study area.Finally,the quality evaluation of geothermal water is carried out.This study draws the following conclusions:(1)Driven by thermal storage lithology,burial depth,geological structure,and geothermal dynamic field,the chemical composition of water exhibits obvious horizontal and vertical distribution characteristics in space.In the horizontal direction,the burial depth,water temperature and TDS of the geothermal water reservoir from the edge of the basin to the center of the basin increase,the geothermal water geological environment is more closed,the reducibility is stronger,the water-rock interaction time is longer,and the hydrochemical type is changed by The HCO₃—Na type and HCO₃·Cl—Na type with lower salinity evolved to the Cl—Na type with high salinity,and a closed circle with high TDS value was formed in Qian'an County and Qianguo County.(2)In the vertical direction,the temperature of geothermal water increases from shallow to deep,but TDS does not simply increase linearly with the burial depth.In Qingshankou Formation and Quantou Formation,the inversion of TDS and stratum burial depth occurs,which may be related to Quentou It is related to the water release and desalination of the thick mudstone developed in the first member of the Formation.According to the relationship between hydrochemical components and burial depth,it can be divided into five hydrochemical profile zones,which are the atmospheric precipitation infiltration zone(100?800m),the mudstone compaction drainage and desalination zone(800m?1300m),and the dissolution and concentration zone(1300?1800m),clay mineral dehydration and desalination zone(1800?2600m)and deep stagnation concentration zone(below 2600m).(3)Na⁺in geothermal water comes from the dissolution of rock salt and the weathering of albite;HCO₃^-comes not only from the dissolution of carbonate minerals,but also from CO₂ generated by organic matter deep in the formation under the environment of temperature and pressure;SO₄~2 not only It is derived from gypsum,and may also be derived from the dissolution of H₂S;Ca²⁺and Mg²⁺are not only derived from gypsum,calcite,and dolomite,but also from anorthite.The quantitative calculation results of hydrogeochemical simulation are consistent with the research results of saturation index.The dissolution of dolomite,gypsum,rock salt,montmorillonite,albite,anorthite,and potassium feldspar and the precipitation of calcite,quartz,chlorite,and illite occurred in the thermal reservoir.(4)The geothermal water in the study area can be mainly used for heating and physical therapy,and is not suitable for irrigation and drinking.The temperature of geothermal water buried in 432.6?2145m is between 25?90?,which can meet the temperature requirements of bathing,greenhouse,breeding,agricultural irrigation,physiotherapy and heating.?150?,which can meet the temperature requirements of drying,power generation and heating.The geothermal water in the study area has high physiotherapy value.It is recommended to mine bromine mineral water from the Yaojia Formation or Qingshankou Formation.All thermal reservoirs are rich in iodine and metaboric acid mineral water,and a single type of mineral water can be produced locally in the depression area.iodine water.