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Modelling and Experiments on Gas Migration in Repository Host Rocks

Objective

For the option of a deep geological disposal facility several potential sources of gases have been identified: i.e. the anaerobic corrosion of iron, degradation of organic materials, the gas present as such in the waste packages. Of those gases hydrogen is certainly the gas which can be released in the potentially largest amount. For the safety evaluation of a repository it is necessary to know the effects of gasses on the host rock.

The primary objective of the MEGAS project is to understand the consequences of gas generation in a clay host rock. The final objective of this project will be to validate a gas migration model and to confirm our understanding using an in situ gas injection experiment.
For the option of a deep geological repository for high level waste, several potential sources of gases were identified: the anaerobic corrosion of iron, degradation of organic materials, generation by gamma radiolysis and the gas present as such in the waste packages. Of those gases, hydrogen is certainly the gas which can be released in potentially the largest amount. For the safety evaluation of a repository it is necessary to know the effects of gases on the host rock.

The primary objective of the MEGAS project is to understand the consequences of gas generation in a clay host rock. The final objective of this project is to validate a gas migration model and to confirm our understanding using an in situ gas injection experiment. Within MEGAS the following phenomena are studied: chemical reaction, diffusion, 2-phase flow and the creation of preferential pathways.
Work programme:

1. Chemical reaction and diffusion experiments
The reaction capacity of hydrogen with Boom clay observed in previous experiments will be further investigated by determining the intrinsic reaction rate, the reaction capacity and the diffusion coefficient.

2. Geotechnical experiments: uniaxial
In these experiments the gas permeability (two-phase flow) and the gas breakthrough pressure will be determined.

3. Geotechnical experiments: triaxial
The goal of these experiments will be to define the conditions under which preferential pathways for gas migration might develop and to examine bubble growth and migration. Triaxial experiments will also be performed at elevated temperature.

4. In situ experiments
These will be performed in the HADES underground research facility (Mol, Belgium).

5. Modelling
The following approaches will be utilized: modelling the dynamics of bubble flow and modelling two phase flow. The laboratory experiments will be used to validate and, possibly, calibrate a basic two phase model.

Coordinator

BELGIAN NUCLEAR RESEARCH CENTRE
Address
200,Herrmann Debrouxlaan 40-42
1160 Bruxelles
Belgium

Participants (3)

Intera Information Technologies Ltd
United Kingdom
Address
Chiltern House 45 Station Road
RG9 1AT Henley-on-thames
Ismes SpA
Italy
Address
Via Levata
24068 Seriate Bergamo
Natural Environment Research Council
United Kingdom
Address

NG12 5GG Nottingham