IDENTIFIABILITY VERSUS HETEROGENEITY IN GROUNDWATER MODELING SYSTEMS

A M BENALI, L W de BACKER

Résumé


Review of history matching of reservoirs parameters in groundwater flow raises the problem of identifiability of aquifer systems. Lack of identifiability means that there exists parameters to which the heads are insensitive. From the guidelines of the study of the homogeneous case, we inspect the identifiability of the distributed transmissivity field of heterogeneous groundwater aquifers. These are derived from multiple realizations of a random function Y = log T  whose probability distribution function is normal.

We follow the identifiability of the autocorrelated block transmissivities through the measure of the sensitivity of the local derivatives DTh = (∂hi  ∕ ∂Tj) computed for each sample of a population N (0; σY, αY). Results obtained from an analysis of Monte Carlo type suggest that the more a system is heterogeneous, the less it is identifiable.


Mots-clés


groundwater modeling ; inverse problem ; identification ; optimisation ; heterogeneity

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Références


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