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tion that the unit of intrinsic permeability, the darcy, was defined (Wyckoff
et al., 1933, 1934).
Equation 8.7 is the general form of Darcy’s law for liquids, and applies to
the flow of any liquid. The intrinsic permeability is independent of the liquid
flowing. As with all such equations, care must be taken with units. Since the
unit of intrinsic permeability is traditionally cm2, mass density should be in
g cm-3, dynamic viscosity (q) inpoise (g cm-’ s-’), and g = 980 cm s-’. For
practical purposes, the darcy is cm2; so the unit of intrinsic permeability
in SI units is likely to be the pm2.