Permeability profiles in granular aquifers using flowmeters in direct-push wells
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Abstract
Numerical hydrogeological models should ideally be based on the spatial distribution of hydraulic conductivity (K), a property rarely defined on the basis of sufficient data due to the lack of efficient characterization methods. Electromagnetic borehole flowmeter measurements during pumping in uncased wells can effectively provide a continuous vertical distribution of K in consolidated rocks. However, relatively few studies have used the flowmeter in screened wells penetrating unconsolidated aquifers, and tests conducted in gravel-packed wells have shown that flowmeter data may yield misleading results. This paper describes the practical application of flowmeter profiles in direct-push wells to measure K and delineate hydrofacies in heterogeneous unconsolidated aquifers having low-to-moderate K (10−6 to 10−4 m/s). The effect of direct-push well installation on K measurements in unconsolidated deposits is first assessed based on the previous work indicating that such installations minimize disturbance to the aquifer fabric. The installation and development of long-screen wells are then used in a case study validating Kprofiles from flowmeter tests at high-resolution intervals (15 cm) with K profiles derived from multilevel slug tests between packers at identical intervals. For 119 intervals tested in five different wells, the difference in log K values obtained from the two methods is consistently below 10%. Finally, a graphical approach to the interpretation of flowmeter profiles is proposed to delineate intervals corresponding to distinct hydrofacies, thus providing a method whereby both the scale and magnitude of K contrasts in heterogeneous unconsolidated aquifers may be represented.
Study Area
Publication type | Article |
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Publication Subtype | Journal Article |
Title | Permeability profiles in granular aquifers using flowmeters in direct-push wells |
Series title | Ground Water |
DOI | 10.1111/j.1745-6584.2010.00761.x |
Volume | 49 |
Issue | 4 |
Year Published | 2010 |
Language | English |
Publisher | Wiley |
Contributing office(s) | National Research Program - Central Branch |
Description | 14 p. |
First page | 534 |
Last page | 547 |
Country | Canada |
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