含水層儲蓄效應對多深度微水試驗資料分析的影響

Effect of Aquifer Storage on Data Analysis of Multilevel Slug Test

孫渥鈞(Wo-jyun Sun)

指導教授 ： 陳家詢

國立中央大學/地球科學學院/應用地質研究所/碩士(2011年)

摘要

多深度微水試驗(MLST)是在井中不同深度進行微水試驗，以獲得水力
傳導係數的垂直分布K(z)。由於MLST 的測試段長度小於含水層厚度，MLST 引起的地下水流為部分貫穿情況。扁平比(井半徑/測試段長度)和部分貫穿比(測試段長度/含水層厚度)會影響部分貫穿井附近的地下水流流場，但是以往討論含水層儲蓄效應時只提到扁平比的影響；當微水試驗中扁平比大於0.08 時受壓含水層的儲蓄效應可以忽略。本研究的目的為探討扁平比和部分貫穿比與含水層儲蓄效應的關係，並找出何種情況下含水層儲蓄效應可以忽略。同時利用暫態(考慮儲蓄效應)模式和類穩態(忽略儲蓄效應)模式於受壓和非受壓含水層中，並以暫態和類穩態模式進行比較，將比較結果區分為高滲透性和低滲透性，得出含水層儲蓄效應可以忽略(1)當高滲透性受壓含水層中部分貫穿比小於0.03 且扁平比小於5;(2)高滲透性非受壓含水層中扁平比小於5 且儲蓄效應的影響與部分貫穿比無關。對於低滲透
性含水層，無論是受壓或非受壓，儲蓄效應皆不可忽略，且儲蓄效應的影響與部分貫穿比無關。

關鍵字

儲蓄效應 ； 多深度微水試驗 ； 暫態 ； 部分貫穿比 ； 扁平比 ； 類穩態

並列摘要

The multilevel slug test (MLST) is to conduct a number of depth-specific slug tests at various depths in a well for the determination of the vertical distribution of hydraulic conductivity, K(z). The test length of each depth-specific slug test is set less than aquifer thickness, so the flow induced is under a partially penetrating condition. It is known that both the aspect ratio (well radius / the test
section length) and the partial penetration ratio (the test section length/ aquifer thickness) play important roles in affecting the flow field close to a partial penetrating well. However, only the aspect ratio has been taken into account when assessing the influence of aquifer storage for MLSTs; that is, aquifer storage can be neglected when the aspect ratio is larger than 0.08 for a slug test in a confined aquifer. Therefore, the purpose of this study is to evaluate the influence of the aspect ratio and the partial penetration ratio on the negligence of aquifer storage. A transient model with aquifer storage effect and a
quasi-steady-state model neglecting aquifer storage are developed for both the confined and unconfined aquifers. The comparison of these two models under high–K and low-K conditions reveals that aquifer storage can be neglected when (1) the aspect ratio is less than 5 and the partial penetration ratio is less than 0.03 in high-K confined aquifers, and (2) the partial penetration ratio is less than 5 in high-K confined aquifers, regardless of the aspect and partial penetration ratios.For either confined or unconfined aquifers of low-K condition, aquifer storage
can’t be neglected. regardless of the aspect and partial penetration ratios.

並列關鍵字

trasient state ； partial penetrating ratio ； aspect ratio ； storage effect ； multilevel slug test ； quasi-steady state

參考文獻

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﹝4﹞ Bouwer, H. and Rice, R. C., “A slug test for determining hydraulic conductivity of unconfined aquifers with completely or partially penetrating wells ”, Water Resource Research, 12(3), 423-428, 1976.

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