利用CT影像分析台灣西部濱海地區砂岩水力參數尺度效應;Use CT images to assess the scale effect and variations of hydraulic parameters of sandstone samples in western coastal area of Taiwan

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Title:	利用CT影像分析台灣西部濱海地區砂岩水力參數尺度效應;Use CT images to assess the scale effect and variations of hydraulic parameters of sandstone samples in western coastal area of Taiwan
Authors:	伍韻安;Wu, Yun-An
Contributors:	應用地質研究所
Keywords:	X光電腦斷層掃描;孔隙尺度;影像處理;水力參數;X-ray CT;pore scale;image processing;hydraulic parameters
Date:	2018-08-22
Issue Date:	2018-08-31 15:06:13 (UTC+8)
Publisher:	國立中央大學
Abstract:	X光電腦斷層掃描技術(X-ray CT)的發展有助於岩石內部微觀構造的觀察，藉由CT影像可以非破壞性的方式取得岩石的重要物理特性如孔隙率、滲透率、曲折度等。本研究使用影像解析度為2微米(μm)的砂岩試體CT影像，試體取自彰濱觀測井(TPCS-M1)2409 m深度處(桂竹林層魚藤坪砂岩段)與2531 m深度處(觀音山砂岩)，量化該區域岩石孔隙率與滲透率的尺度效應。本研究使用Avizo軟體進行CT影像處理，包含影像濾波、影像二值化，影像切割，研究內容分為三大部份：第一部份為以孔隙尺度分析岩石的孔隙率與滲透率空間分布，試體滲透率為使用Kozeny-Carman方程式計算而得，結果指出使用CT影像分析之砂岩樣本平均孔隙率約為24.5%，平均滲透率約為5E-14 m²，此方法較與高圍壓試驗結果相差了一至兩個數量級，原因本研究認為是Kozeny-Carman方程式中的參數設定與假設；第二部份為評估兼顧掃描成本與影像品質之最佳掃描解析度，影像解析度須達16 μm以上，CT影像才較適合做孔隙分析；第三部份為分析樣本之水力擴散係數，本研究改變分析之單位體積，結果指出在單位體積最小為100 μm時，水力擴散係數亦會不同，具有尺度效應。;The technologies of X-ray CT have improved the understanding of geological microstructures, including micro fractures, tortuosity, porosity, permeability, and other important features in rocks. This study aims to quantify the scale effect involved in a relatively homogeneous sandstone rock sample in Kueichulin Formation Yutengping Sandstone (2409 m depth) and Kuanyinshan Sandstone (2531 m depth) in western Taiwan. The variations of sampling volumes are assessed based on 2 μm resolution CT images. The commercial software Avizo is used to do the image processing, which is an important step, including image filtering, binarization and extraction. There are three parts in this study. First, the spatial distribution of porosity and permeability are estimated in the pore scale. The permeability is estimated by the Kozeny-Carman equation. The results show that the average porosity is 24.5% and the average permeability is 5E-14 m², which are one to two order lower than the confining pressure test. Second, in order to do the pore analysis , the best scanning image resolution should be higher than 16 μm. Third, this study analyze the hydraulic diffusivity of sample. The unit volume size is changed into different size. The results show that even when the unit volume size is 100 μm, the hydraulic diffusivity is even different in different size, the scale effect exists.
Appears in Collections:	[Graduate Institute of Applied Geology] Electronic Thesis & Dissertation

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