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Geofluids
Volume 2018, Article ID 6873298, 25 pages
https://doi.org/10.1155/2018/6873298
Research Article

Migration of Gas in Water Saturated Clays by Coupled Hydraulic-Mechanical Model

IRSN, PSE-ENV/SEDRE/LETIS, BP 17, 92260 Fontenay-aux-Roses, France

Correspondence should be addressed to Magdalena Dymitrowska; rf.nsri@akswortimyd.aneladgam

Received 9 June 2017; Accepted 11 December 2017; Published 11 March 2018

Academic Editor: Ian Clark

Copyright © 2018 Aliaksei Pazdniakou and Magdalena Dymitrowska. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Understanding the gas migration in highly water saturated sedimentary rock formations is of great importance for safety of radioactive waste repositories which may use these host rocks as barrier. Recent experiments on drainage in argillite samples have demonstrated that they cannot be represented in terms of standard two-phase flow Darcy model. It has been suggested that gas flows along highly localized dilatant pathways. Due to very small pore size and the opacity of the material, it is not possible to observe this two-phase flow directly. In order to better understand the gas transport, a numerical coupled hydraulic-mechanical model at the pore scale is proposed. The model is formulated in terms of Smoothed Particle Hydrodynamics (SPH) and is applied to simulate drainage within a sample reconstructed from the Focused Ion Beam (FIB) images of Callovo-Oxfordian claystone. A damage model is incorporated to take into account the degradation of elastic solid properties due to local conditions, which may lead to formation of new pathways and thus to modifications of fluid transport. The influence of the damage model as well as the possible importance of rigid inclusions is demonstrated and discussed.