天津地区地热流体主要离子组分特征及地热成因分析  

The characteristics of the main ion components of geothermal fluid and geothermal origin analysis in Tianjin

作　　者：王冰[1] 宗振海[1] 夏雨波 张芬娜[1] 贾志[1] WANG Bing;ZONG Zhenhai;XIA Yubo;ZHANG Fenna;JIA Zhi(Tianjin Geothermal Exploration and Development-Designing Institute,Tianjin 300250,China;Tianjin Center,China Geological Survey,Tianjin 300170,China)

机构地区：[1]天津地热勘查开发设计院,天津300250 [2]中国地质调查局天津地质调查中心,天津300170

出　　处：《华北地质》2023年第2期9-16,共8页North China Geology

基　　金：天津市规划和自然资源局项目“天津市地热资源开发利用动态监测(JGDGP-2019-B-058)”。

摘　　要：天津地区中低温地热资源丰富,地热资源开发利用历史悠久,多年的勘查和开发利用取得了丰富的勘查成果。在研究天津地区地质构造和主要热储层地热流体水化学特征的基础上,本文以天津地区大量的地热流体水化学数据为研究对象,选取主要热储层地热流体中的主要离子与矿化度之间的关系分别进行R聚类分析和相关分析,结果表明,K+含量在裂隙热储层中普遍高于孔隙型热储,且与矿化度的相关性不高;Na^(+)含量、Ca^(2+)含量与矿化度呈明显的正相关关系,且相关性较高;裂隙热储中地热流体的Cl^(-)、SO_(4)^(2-)含量高于孔隙型热储中的地热流体,且与矿化度呈正相关关系;HCO_(3)^(-)含量则与矿化度关系不大。采用元素比例系数法分析天津地区地热流体特征离子,得知天津地区基岩型地热系统相对比较封闭,有利于地热流体的形成和保存;地热流体属于海相含盐沉积岩溶滤水。综合地热流体水文地球化学、同位素和补给条件等资料分析,天津地区地热水的补给来源为大气降水,入渗水在深循环过程中受到地层围岩的加温过程,并与海相沉积的碳酸盐岩发生溶滤作用,最终形成大气渗入-海相沉积的混合成因溶滤水。Tianjin contains abundant low-temperature geothermal resources.The exploration and utilization of geothermal resources has a long history.After years of exploration and utilization,rich exploration results have been achieved.Based on the study of geological structure and hydrochemistry characteristics of geothermal fluid in main thermal reservoirs in Tianjin,this paper took a large number of geochemical data as the research object,and selected characteristic ions and mineralization degree of geothermal fluid in main thermal reservoirs to conduct R-cluster analysis and correlation analysis.It showed K+in fractured reservoir is generally higher than that in porous reservoir,and the correlation between K+and mineralization degree is low;Na^(+)and Ca^(2+)are positively correlated with mineralization degree,and the correlations were high;Cl^(-)and SO_(4)^(2-)of geothermal fluid in fractured reservoir were higher than those in porous reservoir,and they were positively correlated with mineralization degree;HCO_(3)^(-)had little correlation with mineralization degree.It used element proportional coefficient method to analysis hydrochemistry characteristics of geothermal fluid in Tianjin.It showed the bedrock geothermal system was relatively closed,which was conductive to the formation and preservation of geothermal fluid;the geothermal fluid belongs to marine saline sedimentary karst filtration.After comprehensively analyzing the data of hydrogeochemistry,isotopes and recharge conditions of geothermal fluid,it shows that the atmospheric precipitation is the supply source of geothermal water in Tianjin,the infiltration water is heated by the surrounding rock in the process of deep circulation and leaching with marine sedimentary carbonate rocks.Finally,the atmospheric infiltration-marine sedimentation mixed genetic dissolved filtered water is formed.

关 键 词：天津地区 地热流体 R聚类分析 矿化度 元素比例系数法 

分 类 号：P314[天文地球—固体地球物理学]