Numerical interpretation of gas transport experiments on water-saturated samples of Opalinus clay

Titre du congrès :Clays in natural and engineered barriers for radioactive waste confinement Ville du congrès :Lille Date du congrès :17/09/2007

The understanding of gas transport processes through the host rock forms a key issue in the assessment of long-term safety of radioactive waste repositories in argillaceous formations (Marschall et al., 2005). The gas transport capacity of such ultra-low permeability rock formations can be tested in the laboratory by gas breakthrough tests on core samples. A series of gas breakthrough tests using either Helium or Argon on small cylindrical samples (Ø2.4cm, height ~ 2cm) of the Opalinus Clay (Mont Terri, Switzerland) has been conducted by Krooss and Alles, 2006. The experimental data and conditions were carefully reviewed and an interpretation was performed taking into account both two-phase flow (water and gas) and diffusive transport of gas in the aqueous phase by means of numerical simulations.