Definition(s)
Darcy
Permeability of a porous medium, where one darcy is the flow of a single-phase fluid of 1 cP viscosity that completely fills the voids of the porous medium, flowing through the medium under conditions of viscous flow at a rate of 1 ml s-1 cm-2 cross-sectional area and under a pressure or equivalent hydraulic gradient of 1 atm cm -1. NOTE 1 cP 1= mPa s.
Source: API RP 13B-1, Recommended Practice for Field Testing Water-based Drilling Fluids, Fourth Edition, March 2009. Global Standards