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Université de Neuchâtel

Truncated Plurigaussian Simulations to Characterize Aquifer Heterogeneity

Mariethoz, Grégoire ; Renard, Philippe ; Cornaton, Fabien ; Jacquet, Olivier

In: Ground Water, 2009, vol. 47, no. 1, p. 13-24

Integrating geological concepts, such as relative positions and proportions of the different lithofacies, is of highest importance in order to render realistic geological patterns. The truncated plurigaussian simulation method provides a way of using both local and conceptual geological information to infer the distributions of the facies and then those of hydraulic parameters. The method (Le...

Université de Neuchâtel

Understanding diagnostic plots for well-test interpretation = Comprendre l’utilisation des graphes de diagnostic pour l’interprétation des essais de pompage

Renard, Philippe ; Glenz, Damian ; Mejias, Miguel

In: Hydrogeology Journal, 2009, vol. 17, no. 3, p. 589-600

Dans le domaine de l’interprétation des essais de pompage, un graphe de diagnostic est un graphe simultané du rabattement et de sa dérivée logarithmique en fonction du temps. Ce graphe est habituellement représenté en échelle bi-logarithmique. Les avantages principaux et les limites de cet outil sont discutés à l’aide de trois exemples hydrogéologiques réels. Des recommandations...

Université de Neuchâtel

Geological stochastic imaging for aquifer characterization

Mariéthoz, Grégoire ; Renard, Philippe (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2009 ; Th. 2105.

Accurately modeling connectivity of geological structures is critical for flow and transport problems. Using multiple-points simulations is one of the most advanced tools to produce realistic reservoir structures. It proceeds by considering data events (spatial arrangements of values) derived from a training image (TI). The usual method consists in storing all the data events of the TI in a...

Université de Neuchâtel

The future of hydraulic tests

Renard, Philippe

In: Hydrogeology Journal, 2005, vol. 13, no. 1, p. 259-262

Université de Neuchâtel

Calculating equivalent permeability: a review

Renard, Philippe ; de Marsily, G.

In: Advances in Water Resources, 1997, vol. 20, no. 5-6, p. 253-278

The purpose of this article is to review the various methods used to calculate the equivalent permeability of a heterogeneous porous medium. It shows how equivalence is defined by using a criterion of flow or of the energy dissipated by viscous forces and explains the two different concepts of effective permeability and block permeability. The intention of this review is to enable the reader to...

Université de Neuchâtel

Issues in characterizing heterogeneity and connectivity in non-multiGaussian media

Kerrou, Jaouher ; Renard, Philippe ; Hendricks Franssen, Harrie-Jan ; Lunatic, Ivan

In: Advances in Water Resources, 2008, vol. 31, no. 1, p. 147-159

The performances of kriging, stochastic simulations and sequential self-calibration inversion are assessed when characterizing a non-multiGaussian synthetic 2D braided channel aquifer. The comparison is based on a series of criteria such as the reproduction of the original reference transmissivity or head fields, but also in terms of accuracy of flow and transport (capture zone) forecasts when...

Université de Neuchâtel

Stochastic Hydrogeology: What Professionals Really Need?

Renard, Philippe

In: Ground Water, 2007, vol. 45, no. 5, p. 531-541

Quantitative hydrogeology celebrated its 150th anniversary in 2006. Geostatistics is younger but has had a very large impact in hydrogeology. Today, geostatistics is used routinely to interpolate deterministically most of the parameters that are required to analyze a problem or make a quantitative analysis. In a small number of cases, geostatistics is combined with deterministic approaches to...

Université de Neuchâtel

La fin des certitudes ?

Renard, Philippe

In: Bulletin d’Hydrogéologie, 2008, vol. 22, p. 1-20

2006 fut l’année anniversaire des 150 ans de la naissance de l’hydrogéologie quantitative. La théorie des variables régionalisées, ou géostatistique, est beaucoup plus jeune mais a eu un impact majeur. Aujourd’hui, tout étudiant manie avec brio le krigeage que ce soit pour cartographier une contamination, un champ de transmissivité, ou le toit d’une nappe. Mais la géostatistique...

Université de Neuchâtel

Forecasting the Number of Soil Samples Required to Reduce Remediation Cost Uncertainty

Demougeot-Renard, Hélène ; de Fouquet, Chantal ; Renard, Philippe

In: Journal of Environmental Quality (JEQ), 2004, vol. 33, p. 1694-1702

Sampling scheme design is an important step in the management of polluted sites. It largely controls the accuracy of remediation cost estimates. In practice, however, sampling is seldom designed to comply with a given level of remediation cost uncertainty. In this paper, we present a new technique that allows one to estimate of the number of samples that should be taken at a given stage of...