地下熱水儲集層的溫度將是決定地熱能源是否具備開發潛能相當重要的一項因 子。以地球化學方式估算地下熱水儲集層的溫度是一種很好的工具，此種方式即所謂 “地質溫度計”。 地質溫度計是利用地熱流體的化學成份及其含量，作為地下熱水儲集層的溫度依 據，這些地熱流體的成份之含量在不同溫度條件之下，地熱流體與礦物之間的反應關 係會有所差異。現今最常被利用的地質溫度計包括二氧化矽、鈉-鉀、鈉-鉀-鈣及氧同 位素等四種地質溫度計。然而，地球化學模擬能提供定量分析，足以進一步了解在不 同溫度條件下，地熱流體與不同礦物之反應關係，因此，綜合這些結果能得知地下地 熱儲集層的溫度及地熱流體流經路徑。另外，利用溫泉區圍岩岩脈中與地熱流體相關 的液包體分析得以建立地熱流體沉澱當時的溫度及壓力條件。 本計畫將擬以三年的時間進行，各別針對沉積岩區關子嶺以南、火成岩區大屯火 山群及變質岩區知本以南等地區為研究對象。再者，分析這些溫泉的主要元素含量及 穩定同位素、圍岩的礦物組成、溫泉露頭周圍沉澱物，以及圍岩岩脈中與地熱流體相 關的礦物相及其液包體分析。最後，綜合這些結果可得知地質溫度計的適用性並以 “Geochemist’s Workbench (GWB)地球化學分析軟體”得以模擬地熱流體流經路徑。然 而，利用溫泉區的液包體得以建構不同地區地熱系統之地熱流體沉澱當時的溫度及壓 力條件。 The geothermal energy is identified the internal thermal energy of the Earth. In geothermal systems, the geothermal potential is controlled by enthalpy/temperature, permeability distribution, and reservoir depth. The geothermometer is a useful tool for estimate the temperature of geothermal reservoir. The geothermal compositions are controlled by temperature-dependent between fluid and minerals. In generally, there are four geothermometries, including the geothermometers of silica, Na/K, Na-K-Ca, and oxygenic isotope, to estimate the temperature of the geothermal reservoir. A “model” is a simplified version of reality that is useful as a tool. Geochemical model can provide a quantitative method for water-rock interaction and understand the processes and flow path of water-rock interaction of different geological terrain. However, the fluid inclusion provides information of geochemical history. According to the previous studies, it is a high geothermal potential area and has abundance of thermal water in Taiwan. This proposal focuses on the Kuantzuling, Tatun Volcano Group and Chihpen areas and is consist of three aspects. The first one is to analyze various isotopes and major elements of thermal water and to use four geothermometries for calculating temperature of the geothermal reservoir. The second aspect is to model the flow path of geothermal fluid and water-rock interaction by the Geochemist’s Workbench software. The third is to examine fluid inclusion with mineral assemblage from wall rock to establish the geochemistry history of the geothermal system.
