地热能是一种可再生的清洁能源，合理开发利用地热资源是应对全球气候变化和节能减排的重要途径之一。雄安新区位于华北平原冀中拗陷，热流背景值较高，地热资源丰富。但是雄安新区地热资源开发程度不一，对地热水的水化学性质和规律等认识不够全面，研究该区地热水的水文地球化学特征，对认识雄安新区地热资源、科学合理开发利用地热能，推进北方地区冬季清洁取暖具有重要意义。

本研究以雄安新区不同热储地热水为研究对象，通过野外实地调查、地热井水温测定、地热水采集与测试等手段，对容城凸起、牛驼镇凸起、霸县凹陷、保定凹陷和高阳低凸起五个构造单元内不同地热水的水化学和同位素特征进行分析，并利用地球化学温标估算地热水的热储温度，进而得出温度场分布规律。

研究区内分布有砂岩热储和岩溶热储，其中明化镇组和馆陶组砂岩热储，埋深相对较浅，水化学类型以Cl·HCO3-Na型和Cl-Na型为主。雾迷山组岩溶热储，水化学类型主要为Cl·HCO3-Na型。由于岩溶储层均一化程度高，水化学特征空间差异相对较小。由浅入深，地热水TDS值呈增大趋势。受断裂带导水作用影响，部分深部雾迷山组与馆陶组地热水发生混合现象。地热水中F、Br、Li、B、Sr等微量元素相对富集，雾迷山组地热水中微量元素浓度高于馆陶组。雾迷山组地热水的变质系数和脱硫系数低于馆陶组，热储封闭性较好，处于相对还原状态，而馆陶组和明化镇组地热水封闭性相对较差。

氢氧稳定同位素特征显示，浅层地下水和明化镇组地热水，主要来自大气降水补给。相比馆陶组地热水，雾迷山组氢氧稳定同位素变化范围较小。雾迷山组和部分馆陶组地热水δ18O值增大，水岩作用程度增大。雾迷山组地热水87Sr/86Sr比值、锶含量均比馆陶组高。区内地热水14C含量基本小于0.44pmC，地下水年龄超过了14C方法的定年极限，与第四系地下水相比，热储层地下水的可更新能力非常弱。

根据Na-K-Mg三角图判断地热流体矿物平衡状态，雾迷山组地热水未达到水岩平衡，馆陶组地热水达到部分平衡。应用地球化学温标，估算不同储层的地热水热储温度，并与实测井温进行对比，结果显示馆陶组最适合Na-K温标和玉髓溶解度温标，雾迷山组最适合玉髓溶解度温标。基于筛选出的温标方法对比了不同储层地下热水温度。结果显示雾迷山组热储，在牛驼镇凸起和容城凸起地热水温度相对较高。馆陶组热储在高阳低凸起温度较高，而在容城凸起和牛驼镇凸起热储温度相对较低，这与热储埋藏深度相对应。深部雾迷山组地热水的主要补给来源为西部太行山区。

Geothermal energy is a kind of renewable clean energy. Rational development and utilization of geothermal resources is one of the important ways to deal with global climate change and energy conservation and emission reduction. Xiongan New Area is located in Jizhong depression of North China Plain, with high background value of heat flow and abundant geothermal resources. However, the degree of development of geothermal resources in Xiongan New Area is different, and the understanding of the hydrochemical properties and laws of geothermal water is not comprehensive. The study of the hydrogeochemical characteristics of geothermal water in this area is of great significance to understand the geothermal resources in Xiongan New Area and to promote the clean heating in winter in northern China.

Taking geothermal water of different thermal reservoirs in Xiongan New Area as the research object, the hydrochemical and isotopic characteristics of geothermal water in Rongcheng uplift, Niutuozhen uplift, Baxian depression, Baoding depression and Gaoyang low uplift were studied by means of field investigation, determination of geothermal well temperature, geothermal water collection and testing. Different geochemical thermometers were used to estimate the storage temperature of geothermal water, and then the distribution law of geothermal water was obtained.

There are two types of thermal reservoir in the study area: sandstone and karst thermal storage. Minghuazhen formation and Guantao formation had relatively shallow buried depth, and the hydrochemical types were mainly Cl·HCO3-Na and Cl-Na. The main hydrochemical type of Wumishan formation was Cl·HCO3-Na. Due to the high degree of homogenization of karst reservoir, the spatial difference of hydrochemical characteristics was relatively small. From shallow to deep, the TDS value of geothermal water increased. Due to the influence of the water conduction in the fault zone, the mixing phenomenon of geothermal water in some deep Wumishan and Guantao formation occurred. Trace elements such as F, Br, Li, B and Sr were relatively enriched in the geothermal water. The concentration of trace elements in Wumishan formation was higher than that of Guantao formation. The metamorphic coefficient and desulfurization coefficient of geothermal water in Wumishan formation were lower than that of Guantao formation, and the thermal storage was relatively closed and in relatively reduced state, while the sealing of geothermal water in Guantao formation and Minghuazhen formation was relatively poor.

The stable isotope characteristics of hydrogen and oxygen showed that the shallow groundwater and the geothermal water of Minghuazhen formation were mainly supplied by atmospheric precipitation. Compared with the geothermal water of Guantao formation, the variation range of deuterium and oxygen stable isotopes of Wumishan formation was smaller. The increase of 18O value of geothermal water in Wumishan formation and partial Guantao formation indicated water rock interaction deepened. The 87Sr/86Sr ratio and strontium content of geothermal water in Wumishan formation were higher than those in Guantao formation. The 14C content of geothermal water in the area was basically less than 0.44pmC, and the age of groundwater exceeded the limit of 14C dating method. Compared with quaternary groundwater, the renewable ability of groundwater in thermal reservoir was very weak.

The Na-K-Mg triangle diagram was used to judge the mineral equilibrium state of geothermal fluid. The geothermal water of Wumishan formation belonged to immature water, and the geothermal water of Guantao formation was mainly located in partial equilibrium area. Based on the geochemical thermometers, the geothermal water temperature of different reservoirs was estimated and compared with the measured well temperature to determine the optimal geochemical thermometers. Guantao formation was most suitable for Na-K geothermometer and chalcedony solubility geothermometer, while Wumishan formation was most suitable for chalcedony solubility geothermometer. Based on the selected geochemical thermometer, the geothermal water temperature of different reservoirs was compared. The results showed that the geothermal water temperature of Wumishan formation was relatively high in Niutuozhen uplift and Rongcheng uplift. The temperature of Guantao formation was relatively high in Gaoyang low uplift, but relatively low in Rongcheng uplift and niutuozhen uplift, which corresponded to the burial depth of the reservoir. The main recharge source of geothermal water in deep Wumishan formation is Taihang mountain area.