Chemistry and Physics of Minerals and Rocks/Volcanology
Equivalent channel network model for permeability and electrical conductivity of fracture networks
Article first published online: 4 JUN 2002
Copyright 2002 by the American Geophysical Union.
Journal of Geophysical Research: Solid Earth (1978–2012)
Volume 107, Issue B6, pages ECV 1-1–ECV 1-10, June 2002
How to Cite
Equivalent channel network model for permeability and electrical conductivity of fracture networks, J. Geophys. Res., 107(B6), doi:10.1029/2000JB000057, 2002.,
- Issue published online: 4 JUN 2002
- Article first published online: 4 JUN 2002
- Manuscript Accepted: 2 NOV 2001
- Manuscript Revised: 28 OCT 2001
- Manuscript Received: 31 OCT 2000
- equivalent channel
 It is remarkable that the permeability k and electrical conductivity σ of saturated, fractured rock exhibit a power law relationship with exponent r as pressure is applied to the rock. To understand this behavior, the fracture network is viewed as a collection of connected, planar fractures. This allows the construction of algebraic expressions for the transport properties of the fracture network, in which the local effective properties, namely, the hydraulic aperture dh and the electric aperture de of the representative planar fracture (the “equivalent channel”), are distinguished from the network properties (e.g., fracture connectivity) parameterized by the tortuosity factors τh and τe. This “equivalent channel network model” reproduces the observed power law behavior on the conditions that dh3 ∝ der and τh ∝ τer over the range of applied pressures. The first condition is met, as demonstrated by calculations for a variety of simulated planar fractures using the Reynolds equations for fluid and current flow. The value of the exponent r is found to indicate the degree to which the fracture resembles a porous medium but cannot otherwise identify fracture surface or aperture characteristics. No direct evidence currently exists to support the second condition; however, such a power law relationship has been demonstrated elsewhere for simulated porous media.