Computing the Longtime Behaviour of NMR Propagators in Porous Media Using a Pore Network RandomWalk Model.

Abstract : We present a pore network model combined with a random walk algorithm allowing the simulation of molecular displacement distributions in porous media as measured by NMR. A particular feature of this technique is the ability to probe the time evolution of these distributions. The objective is to predict the displacement behaviour for time intervals larger than the experimental observation time and explore the asymptotic dispersion regime at long times. Starting from 3Dmicro-CT images, we computed the variance of displacement distributions of water molecules in a Fontainebleau sand and found very good agreement of the time evolution of the variance with experimental data, without fitting parameter. The model confirms a weak superdispersion in the asymptotic regime. In addition, we conclude that, since pore network models do not take into account small scale features of the porous medium (e.g., surface roughness and grain shape), the origin of the observed superdispersion is mainly due to the topology and geometry of the porous medium.
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https://hal-ifp.archives-ouvertes.fr/hal-00908097
Contributeur : Françoise Bertrand <>
Soumis le : vendredi 22 novembre 2013 - 12:19:04
Dernière modification le : mardi 15 mai 2018 - 14:50:01

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Valentin Guillon, Daniela Bauer, Marc Fleury, Marie-Christine Néel. Computing the Longtime Behaviour of NMR Propagators in Porous Media Using a Pore Network RandomWalk Model.. Transport in Porous Media, Springer Verlag, 2013, 〈10.1007/s11242-013-0243-x〉. 〈hal-00908097〉

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