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Tracer Test Monitoring Using Wells with Long Screened Intervals : Benefits and Disadvantages
Auteur(s)
Schnegg, Pierre-André
Flynn, Raymond Matthew
Mallèn, German
Date de parution
2004
In
Articles of the Centre d'Hydrogéologie at the University de Neuchâtel (CHYN), 2004//1-4
Résumé
Analytical and economic limitations often make fully-penetrating wells an attractive alternative for monitoring tracer test responses in aquifers. Modelling of breakthrough curves generated using long-screened (LS) wells in an unconfined gravel aquifer demonstrated that prolonged tailing could be reproduced with a series of partial breakthrough curves. The results suggested tracer arrived at multiple horizons. Subsequent measurements using a mobile downhole fluorometer demonstrated over 95% of tracer arrival occurred over a 2m depth interval. Simulations of complimentary single-well dilution test results, incorporating vertical flow measurements, indicated that tracer arrival occurred in a zone no thicker than 50cm before being transferred to a shallower level in the aquifer via the well. The probability of encountering this tracer-bearing horizon by installing four 1m long piezometers was approximately 1 in 2. The results highlight the importance of appropriate conceptual models and potential benefits/disadvantages faced by the hydrogeologist when dealing with LS wells in tracer tests.
Identifiants
Type de publication
journal article
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