與裂隙、斷層相關的透水地質構造被認為是台灣東北部低度變質岩區的主要地熱流體上湧管道。從1970年代至1990年代早期有一個期間的地熱鑽井與開發，但當時對於地下地熱地質情況尚無法深入瞭解。本論文研究了仁澤地熱區仁澤3號與仁澤4號地熱井的測井曲線和微電阻影像測井，以了解台灣低度變質岩區地下透水地質構造特徵。 測井曲線和微電阻影像測井資料，以確定地下裂隙和流體流動的可能途徑。由測井資料分析，本研究認為現代的測井資料在低度變質岩區會對透水結構有響應，故可辨視透水裂隙的存在。在微電阻影像測井上，本研究拾取了地層層面、天然開放裂縫及封閉裂隙等地質特徵。整合測井解釋、裂隙位態及裂隙密集度等資訊，本研究證實地下主要的透水地質構造為：1. 以斷層角礫岩為主要結構的斷層核芯與2.大量透水破裂面為特徵的斷層破裂帶。絕大部分開放裂隙為東北-西南方向，與目前區域大地水平最小主應力方向垂直。 本研究發現仁澤地熱區為一個東北-西南走向的狹窄斷層相關地熱系統。此透水的斷層系統的位態約是N50˚-70˚E，向西北方向傾斜70˚-90˚。斷層系統的水平的寬度約為200公尺。斷層系統內部包含了數個斷層帶。斷層帶內發育有透水斷層角礫岩及開放裂隙面。此斷層系統及內部的透水地質構造的發育及特性與岩性及近期台灣東北部的伸張大地構造狀態有關。本研究的資料及研究方法有利於台灣未來的地熱探勘與開發。;Permeable geological structures associated with fractures and faults are considered to be the main upwelling conduits for geothermal fluids in the low-grade metamorphic areas of northeastern Taiwan. From 1970s to early 1990s, there was a period of geothermal drilling and development, but at that time, it was not easy to understand the subsurface geothermal geology. This thesis studied the standard open-hole logs and micro-resistivity formation image (FMI) log of the JT-3 and JT-4 wells in the Jentse geothermal area in order to understand the characteristics of subsurface permeable structures in the low-grade metamorphic rock area of Taiwan. The standard open-hole logs and FMI images were used to identify possible conduits of subsurface fractures and fluid flow. This study concluded that modern standard open-hole log data would respond to permeable structures could be used to identify the presence of permeable fractures in low-level metamorphic rocks of Taiwan. On the FMI images, this study picked geological features such as bedding planes, natural open fractures and closed fractures. Integrating the interpretation results of standard open-hole logs, orientations of fractures and fracture densities, this thesis confirms that the main permeable geological structures in the subsurface are 1. fault cores with fault breccia and 2. fault damage zones characterized by a large number of permeable open fracture planes. The majority of open fractures are oriented northeast-southwest, perpendicular to the direction of current regional minimum horizontal stress. This thesis found that the Jentse geothermal area is a narrow northeast-southwest trending fault-related geothermal system. The strike of this permeable fault system is approximately N50˚-70˚E and dips 70˚-90˚ to the northwest. The horizontal width of the fault system is approximately 200 meters. It contains several fault zones within the fault system. Permeable fault breccias and open fracture surfaces are developed within the fault zones. The development and characteristics of this fault system and the permeable geologic structures within it are related to lithology and the recent tectonic rifting of northeastern Taiwan. The results and methodology of this thesis would be beneficial for future geothermal exploration and development in Taiwan.
