北京市地热水地球化学特征  

Geochemical characteristics of geothermal water in Beijing

作　　者：刘颖超[1,2] 刘凯[2] 孙颖[2] 刘久荣[2] 刘宗明[2] 

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]北京市水文地质工程地质大队,北京100195

出　　处：《南水北调与水利科技》2015年第2期324-329,共6页South-to-North Water Transfers and Water Science & Technology

基　　金：中国地质调查局"全国地热资源调查评价-北京市地热资源现状调查评价与区划"项目(水[2013]01-029-006)

摘　　要：依据北京市不同地热田80组地热水和地下水样品水化学测试结果分析,地热水化学类型自北部山区向南部平原依次可划分为SO4-Na型、HCO3-Na型和Cl-Na型水,中间又有各过渡带水化学类型,而沉积盆地通常是HCO3-Na型地热水;地热水中一些特殊组分如氟、偏硅酸、偏硼酸、硫化氢等含量显著高于常温（冷）地下水。进一步分析认为,北京地热水是由外部圈层冷水在入渗补给过程中经过增温形成的;地热水的组分比率受到蒸发浓缩或冷水稀释的影响较小,冷热水的混入程度不同仍会导致组分比发生变化;各地热田中地热水绝大部分属于未成熟水,热水中水-岩之间尚未达到离子平衡状态。计算表明,北京地热田K-Mg温标的计算温度为38.1℃~136.6℃,SiO2温标的计算温度在57.4℃~154.2℃之间,而实测温度多为22.0℃~118.5℃,估算温度与实测温度的对比可反映钻探可及温度与地热水曾经达到的温度,因此可以为地热勘探提供依据。Based on the chemical analysis on 80 geothermal water and groundwater samples,the geochemical types of the geothermal water vary from SO4-Na in the northern mountain area,HCO3-Na in Beijing Depression,and to Cl-Na in the southern edge of Beijing Plain.The concentrations of F-,SiO32-,BO2-,and H2 S in geothermal water are higher than those in cold groundwater.Further analysis suggests that the geothermal water is formed by the temperature increasing of peripheral cold water during the infiltration process.The results show that evaporation concentration and cold water dilution have insignificant effects on the component ratios of Na/K,Cl/F,Cl/B,and Cl/SiO2;however,the mixing degree between cold and hot water can affect the ratios.Most of the geothermal water is immature,and the water-rock interaction has not reached ion balance.The calculated K-Mg geothermometer temperature ranges from 38.1to 136.6 ℃,the calculated quartz temperature ranges from 57.4to 154.2 ℃,and the well head temperature of geothermal water ranges from 22.0to 118.5℃.The comparison between the calculated and measured temperatures reflects the temperature which the bore can reach and the highest temperature of the geothermal water.The results can provide the hydrogeochemical evidence for geothermal water exploitation in Beijing.

关 键 词：水化学 特殊组分 组分比 温标 

分 类 号：P314[天文地球—固体地球物理学]