Modelling of Gas Migration in Clay

Abstract

The option of the disposal of radioactive waste in a deep clay layer is actually studied in Belgium, France, Spain and
Netherlands. Immediately after closure and sealing of a geological radioactive waste repository a range of gases will be generated. Due to the low permeability of the clay materials these gases cannot easily escape. This can lead to an increase in pressure in the repository and to the creation of preferential gas pathways.
In this paper, as a first step towards the development of computational techniques to handle flow of gas through
compacted and natural clays, and to advance in the basic understanding of the gas migration issues associated with
repository safety, the capabilities of a general code for coupled thermo-hydro-mechanical analysis have been explored.
Some laboratory gas injection experiments carried out on natural clay samples have been selected in order to compare
model computations with measured specimen of natural clay performance.
The results show that the contribution of a continuum type of model is a powerful tool for gaining a greater understanding of the gas migration in clay, which is capable of predicting most of observed phenomena in gas flow experiments. It may therefore be appropriated for describe gas migration through a clay barrier in a deep repository.