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Experimental Study of Electrokinetics in Porous Media

Published online by Cambridge University Press:  15 February 2011

David B. Pengra
Affiliation:
Department of Physics and Astronomy, University of Massachusetts, Amherst, MA 01003, U.S.A.
Liang Shi
Affiliation:
Department of Physics and Astronomy, University of Massachusetts, Amherst, MA 01003, U.S.A.
Sidney Xi Li
Affiliation:
Department of Physics and Astronomy, University of Massachusetts, Amherst, MA 01003, U.S.A.
Po-Zen Wong
Affiliation:
Department of Physics and Astronomy, University of Massachusetts, Amherst, MA 01003, U.S.A.
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Abstract

In brine-saturated porous media the existence of a space-charge layer at the solid/liquid interface leads to a coupling between fluid and electric currents. This coupling is seen as a streaming potential (STP) across a porous plug when the fluid flows through it, or conversely, as electroosmosis (ELO) of the fluid when an electric field is applied. The magnitude of these electrokinetic effects depends on the thickness of the space-charge layer relative to the pore size, which in turn depends upon the salinity of the brine. From electrokinetic measurements one can obtain an effective hydraulic radius Reff and an effective zeta-potential at the slipplane ζeff. We have developed a high-sensitivity AC technique that can detect these small coupling effects, and have measured them in a suite of natural and artificial rock samples. We find that Reff and ζeff depend on salinity in ways which may be attributed to the roughness of the pore surfaces.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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