海床地熱資料處理新演算法及西南海域燦堯泥火山熱模型

利用利氏熱探針取得海洋熱流資料已行之有年，其優點是能夠同時量測到海床溫度以及地溫梯度，並藉由自行放熱後的溫度恢復曲線取得熱導係數值，其資料處理的方法主要是以逆推理論擬合溫度衰減曲線所得。然而，前人在資料處理的演算法為需要利用兩階段的計算以及結合經驗公式來克服收斂困難或過慢的問題。為達提升資料處理的可信度及效率，本研究利用新發展成熟的逆推方法:信賴區間法來克服以往所謂收斂困難或過慢的問題，藉此移除經驗公式使得整個資料處理過程更加清晰且簡潔，並利用格點搜尋法來檢驗利用圓柱體熱傳導公式擬合溫度衰減曲線的特性來探討為何以往的逆推方法有著收斂困難或過慢的問題。本研究更並將此新方法應用在燦堯泥火山區域上的六個地熱測站列的資料處理與分析，利用熱流模擬及震測資料解釋探討此區域熱流分布特性。燦堯泥火山在過去的研究中被認為是一個活躍中的泥火山，其下方應有一相對高溫之流體自深部湧至淺部。本研究利用震測資料作為依據，建立泥火山的幾何模型，並利用利氏探針得到的海床溫度與地溫梯度作為邊界條件，以有限元素法建立起二維熱模型剖面。在本研究的假設中，發現燦堯泥火山下方的流體流速需要達到13 cm/yr向上才能夠符合觀測值，與前人所推測之結果解釋一致。

關鍵字

利氏熱探針；熱模型；泥火山；信賴區間法；逆推方法

並列摘要

Marine heat flow surveys typically utilize Lister-type heat probes, which allow multi-penetrations to measure both temperature and thermal conductivity in situ. Over the past decade, the data processing technique of the heat probes usually use a two stages procedure with empirical constrain to overcome the shortcomings of convergent. However, the empirical constrain had never been validated by experimental data and will certainly vary with sediment type. In this study we attempt to simplify the procedure and remove the empirical part with an advantageous inversion scheme. Our algorithm has been tested on both synthetic and field data and the results show a good agreement with previous algorithm. In our study area, the Tsan-Yao mud volcano, we observed high heat flow value on the top of mud volcano by both previous and our data processing algorithm. To understand the mechanism of heat transfer in this area, we construct a 2D thermal model across the mud volcano. The model shows that there is an advection under the mud volcano and causes the high heat flow measurement; we suggest that advection should be caused by the fluid migration beneath the mud volcano. Base on some assumptions, we found that the fluid migration rate beneath the mud volcano should be 13 cm/yr upward to satisfy our heat flow measurement.

並列關鍵字

Lister-type heat probe ； heat flow ； mud volcano ； thermal model ； inverse algorithm

參考文獻

李信宏(2008)，臺灣西南海域之天然氣水合物穩定帶底部與沉積物熱導係數異常之探討，台灣大學海洋研究所碩士論文，台北，60頁。

Barber, A. J., S. Tjokrosapoetro, and T. R. Charlton (1986), Mud Volcanoes, Shale Diapirs, Wrench Faults, and Melanges in Accretionary Complexes, Eastern Indonesia, American Association of Petroleum Geologists Bulletin, 70(11), 1729–1741.

Bear, J., and Y. Bachmat (1990), Introduction to Modeling of Transport Phenomena in Porous Media, Kluwer Academic Publishers, Dordrecht.

Bullard, E. (1954), The Flow of Heat through the Floor of the Atlantic Ocean, Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, 222(1150), 408–429, doi:10.1098/rspa.1954.0085.

Carslaw, H. S., and J. C. Jaeger (1959), Conduction of heat in solids, 2nd. Oxford University Press, London, 510p.

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海床地熱資料處理新演算法及西南海域燦堯泥火山熱模型

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