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年度	108	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	副教授
專案中文名稱	分散式光纖溫度感測器在地下水污染場址之高解析度井下水文地質調查
中文關鍵字	分散式光纖溫度感測器, 熱能示蹤劑, 地下水污染, 水文地質, 模場試驗
專案英文名稱	Using fiber optic distributed temperature sensor as a downhole tool to investigate the hydrogeology with high resolution
英文關鍵字	fiber optic distributed temperature sensor, heat tracer, groundwater contamination, hydrogeology, filed experiment
執行金額	1,499,425元
執行期間	2019/1/1 至 2020/12/31
計畫中文摘要	本專案計畫以分散式光纖溫度感測器(fiber optic distributed temperature, FO-DTS)進行土壤及地下水污染場址水文地質調查，藉由其在空間與時間上的高解析度連續性量測，可針對井下溫度分布與透水不透水區段進行判識。本研究於現地污染場址共進行三次現地試驗量測，根據第一次量測結果，因降雨事件造成井內溫度大幅變化，藉由溫度回復的快慢情況判識井下不同深度的地層透水區段，以此溫度回復法(temperature recovery )為概念，進行第二次與第三次井下注熱水試驗。在第二次現地試驗中，於現地佈設五口井，並設定其中兩口注水井進行注水；在第三次現地試驗中，同樣佈設五口井，並設定其中三口注水井進行注水，於停止注水後，監測井下各深度溫度回復情況，並將量測資料進行溫度校正。除了以DTS進行井下監測外，以地下水數值模式MODFLOW與MT3DMS模擬停止注水後溫度恢復的過程，並藉由PEST率定模式參數，將水文地質參數量化並驗證現地量測結果。研究結果顯示，兩次試驗之量測結果經由溫度校正可大幅提升溫度量測之精準度至0.05度。根據DTS量測結果顯示，於注水井可觀察到在停止注水後，不同深度之溫度回復情況各不相同，藉由溫度回復之快慢速率可判識透水區段。整體而言，除了井E-04以外，每口井之透水區段皆分布於淺層深度(6公尺~9公尺)，不透水區段則分布於中間區段(9公尺~11公尺)，然而井與井間之相對透水性高低仍需透過數值模式量化或複井跨孔試驗方可確認。針對井E-01與E-04兩口井進行數值模擬，模擬結果顯示，經率定後量測值與模擬值具有高度相關性，且誤差極小，根據量化後之水平向水力傳導係數所判識之透水與不透水區段與DTS量測結果相符合。以DTS進行現地監測試驗並由地下水數值模式驗證之結果，可提供污染場址改善與整治上一重要評估，藉由此創新量測技術未來可提升水文地質調查能力。
計畫英文摘要	In this study, the fiber optic distributed temperature sensor (FO-DTS) is applied in a groundwater contaminated sites to investigate it hydrogeological conditions. The permeable zone in a single well can be identified through temperature measurements with high resolution in terms of space and time. Three field tests were conducted. In the first test, the rainfall events caused the large variation of temperature in the well and the permeable zone at different depths can be identified via different rates of temperature recovery. Accordingly, the injection of hot water into the wells was conducted in the second and third tests. Five boreholes with two injection wells were installed with FO-DTS in the second test, and five boreholes with three injection wells were installed with FO-DTS in the third experiment. After stopping injecting the hot water, the rates of temperature recovery at different depths in a single well were monitored and used to evaluate the permeabilities. Besides, the coupled numerical model of MODFLOW and MT3DMS was applied to simulate the process of heat transfer after ceasing injecting the hot water. The automatic parameter estimation software of PEST was used to calibrate the numerical model and the hydraulic conductivities were identified. The results showed that the accuracy of measured temperatures after calibrated can be improved up to 0.05 oC. The rates of temperature recovery every 25cm can be significantly differentiated and the permeable zone can be identified. In general, the shallow depth from 6 – 9 m is more permeable and the middle depth from 9 – 11m is less permeable in each injected well, except well E-04. The simulated results showed that the simulated temperatures can match the observations well and the hydraulic conductivities can be quantiied. The preliminary experiments of FO-DTS as well as the verification of numerical models can provide the improved assessment of remediation in a groundwater contaminated sites. The innovative measurement technique can enhance the capability of hydrogeological survey in the future.