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Insights on pumping well interpretation from flow dimension analysis : the learnings of a multi-context field database

Ferroud Anouck, Chesnaux Romain et Rafini Silvain. (2018). Insights on pumping well interpretation from flow dimension analysis : the learnings of a multi-context field database. Journal of hydrology, (556), p. 449-474.

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URL officielle: https://doi.org/10.1016/j.jhydrol.2017.10.008

Résumé

The flow dimension parameter n, derived from the Generalized Radial Flow model, is a valuable tool to investigate the actual flow regimes that really occur during a pumping test rather than suppose them to be radial, as postulated by the Theis-derived models. A numerical approach has shown that, when the flow dimension is not radial, using the derivative analysis rather than the conventional Theis and Cooper-Jacob methods helps to estimate much more accurately the hydraulic conductivity of the aquifer. Although n has been analysed in numerous studies including field-based studies, there is a striking lack of knowledge about its occurrence in nature and how it may be related to the hydrogeological setting. This study provides an overview of the occurrence of n in natural aquifers located in various geological contexts including crystalline rock, carbonate rock and granular aquifers. A comprehensive database is compiled from governmental and industrial sources, based on 69 constant-rate pumping tests. By means of a sequential analysis approach, we systematically performed a flow dimension analysis in which straight segments on drawdown-log derivative time series are interpreted as successive, specific and independent flow regimes. To reduce the uncertainties inherent in the identification of n sequences, we used the proprietary SIREN code to execute a dual simultaneous fit on both the drawdown and the drawdown-log derivative signals. Using the stated database, we investigate the frequency with which the radial and non-radial flow regimes occur in fractured rock and granular aquifers, and also provide outcomes that indicate the lack of applicability of Theis-derived models in representing nature. The results also emphasize the complexity of hydraulic signatures observed in nature by pointing out n sequential signals and non-integer n values that are frequently observed in the database.

Type de document:Article publié dans une revue avec comité d'évaluation
Numéro:556
Pages:p. 449-474
Version évaluée par les pairs:Oui
Date:2018
Sujets:Sciences naturelles et génie > Sciences naturelles > Sciences de la terre (géologie, géographie)
Département, module, service et unité de recherche:Départements et modules > Département des sciences appliquées > Unité d'enseignement en sciences de la Terre
Mots-clés:Diagnostic plot, drawdown log-derivative signal, flow dimension, Theis-derived models, complex aquifers, field data
Déposé le:24 avr. 2018 20:56
Dernière modification:17 mai 2019 14:46
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