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Uncertainties in the Modelling of Migration

Objective

The objectives of the present investigation is to estimate the uncertainties to be ascribed to the results of modelling calculations of diffusion and convection calculations. Especially the uncertainties which are the consequences of the possible presence of unidentified heterogeneities in a given formation will be considered. Numerous other sources add up to the final uncertainty, like poorly understood and characterised geochemistry, but contrary to the first type of uncertainties, such problems may in principle be solved by intensive and well planned laboratory experiments. Several approaches are possible mostly related to experimental work in the field or the lab. In the present investigation, computer-experiments alone will be used as the tool.
The objective of the present investigation is to estimate the uncertainties to be ascribed to the results of modelling calculations of diffusion and convection calculations. The uncertainties which are the consequences of the possible presence of unidentified heterogeneities in a given formation will be considered in particular. Numerous sources add up to the final uncertainty but, contrary to the first type of uncertainties, such problems may in principle be solved by intensive and well planned laboratory experiments. Several related attempts aiming at decribing the dispersion to be expected when migration proceeds through a complex of fissures have been reported, although measures of the expected uncertainties have not been explicitly stated. Only recently has attention been paid to the uncertainties to be ascribed to migration modelling, wherefore the relevant tools have not been firmly established yet. Several approaches are possible mostly related to experimental work in the field or the laboratory. In the present investigation, computer experiments alone will be used as the tool.

Methods for determinig effective porosities have been developed. Similarly, a program for calculating 3-dimensional diffusion in the formations where diffusion coefficients vary with position has been developed and used. It has been found, that only 3-dimensional calculations are realistic approximations to laboratory and field experiments. Methods for visualising plugged flow dispersions in 2-dimensional systems with inhomogeneities have been developed. A network model in which permeabilities of path sections are randomly generated is being developed for estimating uncertainties and dispersion effects due to convection in fissured formations.
Work programme:

1. To develop an algorithm which will be used for creating two- and three dimensional "synthetic" geological formations with non-homogeneities which positions are selected at random.
2. To develop a mass-conserving algorithm which can handle diffusion in heterogeneous media in both two- and three dimensions.

Call for proposal

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Coordinator

RISOE NATIONAL LABORATORY
EU contribution
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Address
Frederiksborgvej 399
ROSKILDE
Denmark

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Total cost
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