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臺灣能源期刊論文全文

臺灣能源期刊第8卷第3期內容

出刊日期:September, 2021

題目
緻密岩層中透水斷層帶與地熱流體之關係:以中央 山脈板岩帶北段之仁澤地熱區為例
Title
The Relations between Fault Zones and Geothermal Fluids in Tight Rocks: A Case Study in the Slate Belt of the Northern Central Range, Taiwan
作者
陳炳誠、黃緯誠、陳思婷、郭力維、施輝煌
Authors
Bing-Cheng Chen, Wei-Cheng Huang, Shi-Ting Chen, Li-Wei Kuo, Hui-Huang Shih
摘要
臺灣中央山脈板岩帶北段是一具地熱發電潛能的地質區。由於板岩帶岩層緻密,裂隙、斷層與 斷層帶被認為是此區域的地熱流體通道。地下的開放裂隙與斷層帶等,都可作為流體的通道,但在 地熱資源開採上,具良好透水能力的斷層帶應扮演主要的角色。依據中央山脈板岩帶北段內的仁澤 地熱區的井測資料與露頭發現,岩層的透水通道多集中於少數的透水斷層帶附近,並非廣泛發育於 地熱儲集層中。透水斷層帶與裂隙在仁澤地熱區有不同的作用。透水斷層帶是由破碎的斷層核芯及 斷層破裂帶複合組成,為此地質區最良好的地熱流體通道;地熱儲集層中較廣泛存在的開放性裂隙 面主要作用為增加流體與週圍高溫岩體間的熱交換速率,對於地熱流體的有效生產幫助較小。本研 究結果發現,要在板岩區內形成透水斷層帶,控制因素包含適當的岩性、斷層活動方式及斷層活動 史。因需這些適宜的地質條件皆同時存在,要在此地質區發育良好的透水斷層帶並不容易。也因為 現有地質資料仍無法完全了解此地質區內斷層帶在地下的分布與透水品質,預測地下透水斷層帶的 位置、品質與其在地下的延伸,目前為降低此區域地熱探勘與開發風險最關鍵的研究工作之一。
關鍵字
斷層帶,裂隙,地熱流體,板岩帶
Abatract
The slate belt of the northern Central Range is a geological region with geothermal potential in Taiwan. Due to the low porosity and low permeability of the slate formations, conductive fractures, faults, and fault zones are considered important conduits for subsurface geothermal fluids in this area. Between permeable fracture networks and fault zones, permeable fault zones play a more important role than fractures for the production of geothermal fluid. According to the wireline-logging data of the geothermal wells in Jen-Tse, fault zones with porous fault breccia zones and high-density open fracture zones may be main geothermal fluid pathways in the slate belt of the northern Central Range. Based on the logging data, most fractures are clustered in the vicinity of the fault zones rather than widely-distributed in the geothermal reservoir. Permeable fault zones in the slate formation are few in number, narrow in width, and have minor offsets, making them difficult to be observed by surface geological surveys. Identifying the subsurface location and extension of conductive fault zones would be a major difficulty in geothermal exploration and production risks in the slate belt. This study suggests that the role of open fracture networks is to increase the heat exchange efficiency between the fluids in the fractures and the high-temperature host rocks in the slate belt. To acquire high geothermal fluid production for efficient power generation, fault zones with highlypermeable structures would be needed. The development of permeable fault zones in this area requires a combination of suitable lithology, faulting behaviors, and fault activities, which are not easy to occur in this geological setting. In the present, the most important studies to lower the risks of geothermal exploration and production of this area would correctly predict the locations, properties, and subsurface extensions of these rare permeable fault zones.
Keywords
fault zones, fractures, geothermal fluid, slate belt.