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Permeability Profiles in Granular Aquifers Using Flowmeters in Direct-Push Wells.

Paradis, Daniel; Lefebvre, René; Morin, Roger; Gloaguen, Erwan (2011). Permeability Profiles in Granular Aquifers Using Flowmeters in Direct-Push Wells. Ground Water , vol. 49 , nº 4. p. 534-547. DOI: 10.1111/j.1745-6584.2010.00761.x.

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Résumé

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 K profiles 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.

Type de document: Article
Mots-clés libres: characterization methods; consolidated rocks; direct-push; graphical approach; high resolution; hydrogeological models; k-values; slug test; unconsolidated aquifers; vertical distributions
Centre: Centre Eau Terre Environnement
Date de dépôt: 17 févr. 2021 16:14
Dernière modification: 23 mars 2021 15:23
URI: http://espace.inrs.ca/id/eprint/11319

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