HR: 1340h
AN: H23B-1138    [Abstracts]
TI: An Investigation of Surface Phenomena on Electrical Properties of Aquifer Materials
AU: * Bertrand, E A
EM: eabertra@scimail.uwaterloo.ca
AF: University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 Canada
AU: Endres, A L
EM: alendres@sciborg.uwaterloo.ca
AF: University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 Canada
AB: Electrical property measurements of aquifer materials are important in both borehole and surface geophysical methods used to infer subsurface conditions such as porosity, clay content and water saturation. The accuracy of these estimated hydrologic parameters is strongly dependent on the theoretical understanding of the electrical behaviour of the heterogeneous system. This behaviour is known to be affected by both the shape of the constituents in the medium (e.g. porosity, rock grains, clay platelets) and the presence of surface phenomena, such as electrochemical double layers and surface conduction. Past research was commonly restricted to either an accurate treatment of the geometrical or surface effects with limiting approximations applied to treat the other component. We present an exact solution to Laplace's equation inside an ellipsoidal particle subject to boundary conditions specifying a surface conductivity and associated surface current; this result is an extension of the one obtained by O'Konski for a spherical particle. This solution can be readily generalized to spheroidal particles whose morphology can be adjusted to adequately represent components in aquifer materials ranging from elongated rods to spheres to flattened discs. This expression allows the investigation of the effects of surface phenomena on geometrically realistic aquifer constituents using inclusion based models. This new theoretical treatment accurately incorporates surface phenomena on geometrically representative aquifer constituents and is used to investigate the effects clay platelets can have on electrical property versus porosity relationships. The results are directly compared to previous data obtained on analogous systems without surface phenomena.
DE: 5109 Magnetic and electrical properties
DE: 5112 Microstructure
DE: 3210 Modeling
DE: 1866 Soil moisture
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting