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年度	113	專案性質	實驗性質
專案類別	模場試驗	研究主題	調查
申請機構	國立臺灣海洋大學	申請系所	地球科學研究所
專案主持人	邱永嘉	職等/職稱	教授
專案中文名稱	以分散式光纖溫度感測器結合封井材料進行場址地下水流速與流向高解析度調查
中文關鍵字	光纖溫度感測器,封井材料,地下水流速,地下水流向,高解析度調查
專案英文名稱	High-resolution investigation of groundwater flow and direction at the site using fiber-optic distributed temperature sensor combined with well sealing materials
英文關鍵字	Fiber Optic Temperature Sensors, Well Sealing Materials, Groundwater Flow Velocity,Groundwater Flow Direction, High Resolution Survey
執行金額
執行期間	2024/12/15 至 2025/11/29
計畫中文摘要	傳統的水文地質調查方法多以大尺度試驗為主，雖能掌握區域性地下水分布特徵，但在地層構造複雜、含水層非均質性高的場址中，因現地資料空間解析度不足，常導致透水層位置及地下水流速、流向推估的不確定性，進而影響水文地質判釋之準確度。近年來，熱示蹤技術（Thermal Tracing）結合分散式光纖溫度感測系統（Fiber-Optic Distributed Temperature Sensing, FO-DTS）已被證實可於多種水文地質條件下有效解析地下水流動特性。此技術具備高時間與空間解析度、可連續量測及高穩定性等優勢，已成為傳統水文調查方法的重要補充工具。 本研究即以此為基礎，利用 FO-DTS 技術進行地下水流動與熱傳特性之分析，並自製研發單井流速與流向光纖溫度測定儀（Thermal Vector DTS, TV-DTS）。該系統可於單井內同時設置加熱光纖與多方位感測光纖，透過不同方向溫度訊號的差異，不僅能推估井內垂向流速分佈，亦能解析地下水流向，克服現地觀測井數量不足或井位分佈不均之限制。此外，為降低井內垂直熱對流所造成的溫度混合效應，本計畫同步研析兩種暫時性封井材料——柔性襯管（Flexible Liner Underground Technologies, FLUTe）與聚丙烯醯胺凝膠（Polyacrylamide Gel, PAG），以提升加熱試驗之穩定性與流速推估準確度，並評估其於分層水壓監測上的可行性。 本計畫選定屏東潮州新埤地區地下水污染場址為試驗區。截至期末報告截止前，已於兩口監測井（T00483、T00484）完成單井主動加熱試驗，並配合 ADTS 軟體進行流速與熱傳導係數反演，建立垂向流速與熱性質剖面；另以 COMSOL 進行不同封井條件下的數值模擬，並於 T00567 進行 FLUTe 與 PAG 的現地加熱試驗。試驗結果顯示，T00483 井深度 31–43 m 為最透水區段，深度64–80 m 為低透水層；T00484 則在 深度45–50 m 及 70–80 m 為高透水帶，深度40–45 m 及 55–65 m 為低透水帶。ADTS 反演結果指出，T00483 深度 34–39 m 為高流速區，深度50–80 m 為低流速區；其 RMSE 約 0.2–0.6 °C，顯示模型可合理重現溫度變化。T00484 之流速亦隨深度呈明顯變化，低流速區對應於熱傳導係數較高的位置，RMSE 多介於 0.2–0.6 °C，局部升高至 0.8 °C，顯示該區可能存在細部岩性變化或局部異質性。 COMSOL 模擬顯示，僅有水平流動時，低流速層熱量易累積、溫升對比明顯；若井內存在垂直熱對流，熱量混合使溫度場趨於均質，削弱原本由水平流速差主導的分層結構；當加入封井材料（FLUTe 或 PAG）後，垂直對流被有效抑制，熱量重新集中於低流速區，恢復清晰的溫度分層與穩定的時間變化趨勢。此結果證實，垂直對流是造成單井加熱訊號失真與分辨率下降的主因，而封井設計能在低功率輸入下有效提升熱場對比與可判釋性。 根據 FLUTe 與 PAG 的現地加熱試驗結果可知，兩者皆能明顯改善井內溫度穩定性並抑制垂直對流。FLUTe 試驗顯示，封井後雖整體升溫幅度略低，但高、低溫分帶更清楚，熱能主要受地層導熱與局部流速差控制；試驗中期出現的高溫柱狀區為補水維壓之暫時性現象，與地層水流無直接關聯。PAG 試驗中，封井層（深度5–7 m）形成穩定分層，深度6 m 附近溫度上升約 3°C，顯示其能有效降低對流擾動，使溫度變化更能反映地層導熱特性。整體而言，FLUTe 與 PAG 均可顯著提升加熱試驗訊號的清晰度與可靠度，證實封井技術對改善垂直流動干擾、真實反映地下水流動與地層異質性具有明顯成效。 本研究透過 FO-DTS 技術結合單井加熱、數值模擬及封井應用，成功建立高解析度之地下水流速與熱性質剖面，並驗證封井材料於現地試驗的可行性。研究成果可作為污染場址水文地質特性評估與整治規劃的重要依據，亦為未來地下水監測技術之精進與應用提供新的方向與契機。
計畫英文摘要	Traditional hydrogeological investigation methods are generally conducted at a large spatial scale. Although these methods can delineate regional groundwater characteristics, they often lack the spatial resolution required to accurately describe complex and heterogeneous aquifer systems. As a result, uncertainties frequently arise in identifying permeable layers and estimating groundwater flow velocity and direction. In recent years, thermal tracing combined with Fiber-Optic Distributed Temperature Sensing (FO-DTS) has proven to be an effective approach for characterizing groundwater flow under various hydrogeological conditions. This technology provides continuous, high-resolution temperature measurements in both space and time, offering a valuable complement to conventional hydrogeological investigation techniques. In this study, FO-DTS technology was applied to analyze groundwater flow and heat transport processes. A self-developed Thermal Vector DTS (TV-DTS) system was designed to simultaneously install heating and multi-directional sensing fibers within a single well, allowing the estimation of vertical flow velocity distribution and the determination of groundwater flow direction. To minimize vertical thermal convection and improve the reliability of temperature measurements, two temporary sealing materials—Flexible Liner Underground Technologies (FLUTe) and Polyacrylamide Gel (PAG)—were also evaluated. These materials effectively suppress vertical flow and enhance the accuracy of flow estimation while enabling potential applications for multi-level pressure monitoring. The experimental site is located in Chaozhou, Pingtung, southern Taiwan. By the end of this reporting period, single-well active heating tests were completed in two monitoring wells (T00483 and T00484), and the ADTS software was used to invert flow velocity and thermal conductivity profiles. Additionally, a COMSOL model was established to simulate the influence of different sealing conditions, and field-scale heating tests using FLUTe and PAG were conducted in well T00567. Results show that well T00483 exhibits high permeability between the depth of 31–43 m and low permeability below the depth of 64–80 m, while well T00484 has higher permeability zones at the depth of 45–50 m and 70–80 m. The ADTS inversion results indicate consistent trends with temperature data, and RMSE values mostly ranged from 0.2–0.6 °C, confirming good model agreement. COMSOL simulations further demonstrate that, in cases of purely horizontal flow, low-velocity zones exhibit significant heat accumulation and clear vertical stratification. When vertical convection is present, temperature profiles become homogenized, reducing signal contrast. After applying sealing materials (FLUTe or PAG), vertical convection is effectively suppressed, heat accumulates locally, and stratified temperature structures are restored. These findings confirm that vertical convection is the main cause of signal distortion in single-well heating tests, while sealing designs greatly improve thermal contrast and interpretability even under low-power heating conditions. Field tests with FLUTe and PAG further validate the simulation results. FLUTe reduced vertical convection and clarified temperature layering, while the temporary vertical thermal anomaly observed was attributed to pressure maintenance during operation. PAG formed a stable stratified structure in the depth of 5–7 m section, showing temperature increases of approximately 3°C near the depth of 6 m depth, effectively stabilizing the thermal field. Both sealing materials improved temperature signal clarity and reliability, demonstrating their capability to reduce vertical flow interference and to reflect groundwater flow and aquifer heterogeneity more accurately. In conclusion, by integrating FO-DTS with single-well active heating, numerical simulation, and sealing techniques, this study successfully established a high-resolution characterization of groundwater flow velocity and thermal properties. The findings provide a reliable foundation for hydrogeological assessment and groundwater remediation planning, and present new opportunities for the advancement and application of innovative groundwater monitoring technologies.