HR: 17:45h
AN: H44A-08    [Abstracts]
TI: Predictive Models for Hydrodynamic Coupling Coefficients in Clay Media.
AU: * GUEUTIN, P
EM: gueutin@ccr.jussieu.fr
AF: UMR-Sisyphe, UPMC, 4 Place Jussieu, PARIS, 75252, France
AU: * GUEUTIN, P
EM: gueutin@ccr.jussieu.fr
AF: ANDRA, 1 Rue jean Monnet, CHATENAY-MALABRY, 92298, France
AU: Gon\c{c}alvès, J
EM: julio@ccr.jussieu.fr
AF: UMR-Sisyphe, UPMC, 4 Place Jussieu, PARIS, 75252, France
AU: Violette, S
EM: sophie.violette@ccr.jussieu.fr
AF: UMR-Sisyphe, UPMC, 4 Place Jussieu, PARIS, 75252, France
AB: In charged and low permeability media (e.g. clay media) the classical Darcy's law does not describe accurately the water movement. A generalized Darcy's law, one of the coupled fluxes equations, has to be used. The identification of the coupling parameters, in clay-rocks, is crucial in order to estimate the water flow. Here, we will only focus on the electrochemical-hydraulic coupling coefficients : the intrinsic permeability k and the osmotic permeability k_c. These hydrodynamic coupling coefficients can be estimated using two approaches:
\indent(i) theoretical models :
\indent• porosity/intrinsic permeability relationships, defined for a clay medium, are used to estimate the intrinsic permeability.
\indent• an electrochemical model is used to estimate the osmotic coupling coefficient. The electrical model, a triple layer model, is implemented to simulate the interactions between the charged surfaces of the clay minerals and the pore solution.
\indent(ii) experiments :
\indent• at the sample scale.
\indent• at the field scale. The measurement of these parameters is generally challenging either at the sample or at the field scale. For this reason, predictive models can be useful. The purpose of this study is to give reference values for the two coupling parameters under consideration here, using to the petrophysical properties of the medium. Different models to estimate these coupling coefficients are tested :
(i) the intrinsic permeability is estimated with a pretrophysical model. In this model, the intrinsic permeability depends on the effective pore radius and the electrical formation factor.
(ii) the osmotic coupling coefficient is estimated with the model developed by Revil and Leroy (2004). The comparison between three different models with the available data shows that these data are more closely reproduced using this model. Some reference values are provided for several type of clays as a fonction of some readily measurable or estimable parameters or variables, such as the porosity, the solute concentration. \begin{footnotesize} Revil, A. and Leroy, P. (2004). \newblock JGR, 109(B03208):10.1029/2003JB002755. \end{footnotesize}
DE: 1828 Groundwater hydraulics
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2007 Fall Meeting