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

JOURNAL OF HYDROLOGY

卷:556

Article

Ferroud, Anouck¹  Chesnaux, Romain¹  Rafini, Silvain¹ 

[1] Univ Quebec Chicoutimi, Res Grp R2Eau, Ctr Etud Ressources Minerals, 555 Blvd Univ, Chicoutimi, PQ G7H 2B1, Canada

关键词: Diagnostic plot;    Drawdown log-derivative signal;    Flow dimension;    Theis-derived models;    Complex aquifers;    Field data;   

DOI  :  10.1016/j.jhydrol.2017.10.008

来源: Elsevier

【 摘 要 】

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. (C) 2017 Elsevier B.V. All rights reserved.

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