Analysis of Geochemical Characteristics of Geothermal Water in Beijing

Abstract

Based on 80 geothermal water and groundwater samples analysis, the hydrochemistry type of the thermal spring is SO4-Na, the deep oil field water is Cl-Na, the quaternary groundwater is HCO3-Ca or HCO3-Mg and the geothermal water is HCO3-Na. The hydrochemistry types of difference water samples have zone variation, which change from SO4-Na in the northern mountain area to HCO3-Na in Beijing Depression and Cl-Na in the southern edge of Beijing plain. The concentrations of F-, SiO32-, BO2- and H2S in geothermal water are higher than in cold groundwater.The result showed that the ratios of Na/K,Cl/F,Cl/B,Cl/SiO2 have little influence by evaporation concentration or the cold water dilution. The K-Mg geothermometer temperature is calculated from 35 to 140℃, the quartz temperature ranges from 55 to 155℃ and the well head temperature of geothermal water ranges from 22.0 to 118.5℃. The K-Mg geothermometer temperature is higher than the the well head temperature when the well head temperature is lower, and the K-Mg geothermometer temperature is lower than the well head temperature when it’s higher. The K-Mg geothermometer temperature is considered as the temperature the bore can get. The quartz temperature is considered as the highest temperature the hole ever reached during the drilling.