高温热田深部母地热流体的温度计算及其升流后经历的冷却过程: 以腾冲热海热田为例

高温地热系统中赋存着大量的地热能资源.为了进一步了解高温地热系统, 以腾冲热海热田为典型研究区, 利用热泉地球化学组成, 基于多种地球化学模型确定了热田深部母地热流体的温度, 并分析了其升流后经历的不同冷却过程.热海热田的硫磺塘水热区和热水塘水热区所排泄的热泉源自共同的深部热储, 该热储中母地热流体的Cl-质量浓度为265 mg/L, 温度为336 ℃.在热海热田, 母地热流体在经历绝热冷却过程后直接形成了泉口温度最高的大滚锅泉, 而其他中性泉均由母地热流体先与浅部地下冷水混合再经历绝热冷却形成.母地热流体的深部热储之上存在多个温度在200 ℃以上的热储, 这些热储的形成受控于热海地区发育的多组方向不同的断裂. 

Evaluation of Temperature of Parent Geothermal Fluid and Its Cooling Processes during Ascent to Surface:A Case Study in Rehai Geothermal Field,Tengchong

High temperature geothermal system contains plenty of geothermal resources. In order to further understand the high temperature geothermal system, taking the Rehai geothermal field of Tengchong as a typical study area and the geochemical compositions of Rehai hot springs as basic data, the temperature of parent geothermal fluid (PGF) below Rehai is estimated by use of multiple geochemical models, based on which the cooling processes of PGF during its ascent to surface are analyzed as well. The geothermal waters discharged from both Liuhuangtang and Reshuitang of Rehai originate from the same deep reservoir where a parent geothermal fluid with Cl- concentration of 265 mg/L and temperature of 336 ℃ was identified. The Dagunguo spring with the highest vent temperature at Rehai was formed via direct adiabatic cooling of PGF, whereas the other neutral springs are primarily the results of mixing between PGF and shallow cold groundwater, although boiling was also involved after the mixing. Above the deep reservoir containing PGF, there exist many geothermal reservoirs with temperatures higher than 200 ℃. The formation of these reservoirs is possibly controlled by the faults with different stretching directions at Rehai.