Barometric pumping of a fractured porous medium

Valeri V. Mourzenko (1) , C. Varloteaux (2) , S. Guillon (3, 4) , Jean-François Thovert (1) , E. Pili (3, 4) , P. M. Adler (2)

1 PPrime [Poitiers] - Institut Pprime [UPR 3346]
2 METIS - Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols
3 DAM/DIF - DAM Île-de-France
4 IPGP - Institut de Physique du Globe de Paris

Barometric pumping plays a crucial role in the release of trace gases from fractured porous media to the atmosphere, and it requires a rigorous and complete modeling in order to go beyond the approximate schemes available in the literature. Therefore, a coupled set of convection and convection-diffusion equations for a slightly compressible fluid in unsteady conditions should be solved. The numerical methodology is presented, and it is applied to conditions close to the ones of the Roselend Natural Laboratory (France). The precision of the code is assessed and the mechanism of barometric pumping is explained. The usual schematization by simple vertical fractures is shown to be only qualitative. Finally, barometric pumping is shown to be efficient in a narrow range of parameter values; its efficiency is a decreasing function of the matrix porosity and of the fracture density.

Domaines: Géophysique [physics.geo-ph]

Valeri V. Mourzenko, C. Varloteaux, S. Guillon, Jean-François Thovert, E. Pili, et al.. Barometric pumping of a fractured porous medium. Geophysical Research Letters, 2014, 41 (19), pp.6698-6704. ⟨10.1002/2014GL060865⟩. ⟨hal-01196402⟩