Relations Between Permeability and Electrical Resistivity in Granular Aquifers

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Abstract
Increased demand for quantitative answers to ground‐water problems, particularly associated with the use of numerical models, has increased the need to accurately determine the distribution of hydraulic parameters. Researchers have attempted to find correlations between electrical resistivity and the permeability of fresh‐water aquifers since 1951. Several recent studies report either direct or inverse relations between apparent formation factor and aquifer permeability. The basis for these relations is a direct or inverse relation between porosity and permeability and, as matrix conduction effects are not taken into account, constant fluid conductivity is either implicitly or explicitly assumed.Laboratory experiments conducted on granular materials suggest that matrix conduction (surface conduction) effects are either as important as, or dominant over, porosity‐permeability relations. Our experiments on granular materials show only weak relations between true formation factor and permeability. Relations between apparent formation factor and permeability are good only for constant fluid conductivity. Most importantly, the strongest relationship found was that between permeability and matrix conductivity.These data suggest either that (1) relations between permeability and apparent formation factor must be applied in very restricted geologic environments and only where fluid conductivity remains relatively constant, or (2) more fundamental relations between matrix conductivity and aquifer permeability should be applied.