Name: Elke Jacops
Date: July 2, 2018 17:00 h
Auditorium R (ELEC 00.54) from the ElectrotechnicalInstitute (ESAT)
Development and application of an innovative method for studying the diffusion of dissolved gases in porous saturated media
Clays are considered as potential host rocks for the disposal of nuclear waste. Transport of solutes in these formations is dominated by diffusion, and thus characterized by diffusion coefficients. Recently, we developed a new and innovative method to determine diffusion coefficients of dissolved gases. Experiments were performed on different clay-based materials, using different gases (noble gases and light hydrocarbons). Results indicated relationships between the size of the diffusing molecule and its diffusion coefficients, and these relationships could be used to estimate diffusion coefficients, based on the size of a gas molecule. For each sample, a detailed petrophysical and petrographical analysis was performed. Correlation analysis revealed correlations between mineralogy, grain size distribution, specific surface area, volume of micro-pores on the one hand and diffusivity and hydraulic conductivity on the other hand. By performing petrographical analyses, a clear link between the transport parameters and the pore network was observed. In sandy samples, transport is faster which is related to a larger amount of bigger pores, whereas transport is slower in clayey samples as they have a very large part of small pores. The variability in the pore size distribution is a key factor, controlling the transport in clay-based materials.
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