天津市蓟县系雾迷山组地热流体地球化学特征

蓟县系雾迷山组是天津地区最重要的基岩裂隙型热储层。通过对天津市平原区不同构造单元的70组蓟县系雾迷山组地热流体样品的水化学测试,从其化学类型、特殊组分、热储温度及地热水成因等方面进行分析研究。结果表明,流体化学类型北部以HCO_3·SO_4-Na、HCO_3·SO_4·Cl-Na为主,往南变为Cl·HCO_3-Na、Cl·HCO_3·SO_4-Na、Cl·SO_4·HCO_3-Na为主,南部为Cl·SO_4-Na为主;地热流体中的氟、偏硅酸、偏硼酸、温度均达到了"有医疗价值浓度"或"命名矿水浓度"标准;由于雾迷山组地热流体水-岩之间未达到离子平衡状态,K-Mg温标不适用于本地区热储温度的计算,采用玉髓温标来预测热储温度的方法比较适用于本地区的热储。通过成因分析可知该热储属于贫溴的含岩盐地层溶滤水,具有陆相沉积水的特征。

Geochemical characteristics of geothermal fluid in the Wumishan Formation of Jixian System in Tianjin

Wumishan formation of Jixian System is the most important bedrock fracture thermal reservoir in Tianjin area. 70 sets of geothermal fluid sample from different tectonic units of plain area in Tianjin city are analyzed in their water chemistry and the aspects of chemical type, special composition, temperature and genesis of geothermal fluid are studied. The result shows that in the north part the water chemistry type is dominated by HCO₃·SO₄-Na, HCO₃·SO₄·Cl-Na, southward by Cl·HCO₃-Na, Cl·HCO₃·SO₄-Na, Cl·SO₄·HCO₃-Na and in the south part by Cl·SO₄-Na. Temperatures, fluorine, metasilicic acid and metaboric acid concentration of the geochermal fluid reach the medical standard mineral water standard. Because the geothermal fluid-rock reaction is not in ionic equilibrium K-MG thermometric scale is not suitable for the prediction of the local reservoir temperature. Origin of geothermal water reveals that the geothermal reservoir belongs to bromide-poor rock salt layer infiltration water type characterized by continental sedimentary water.