1. n. [Formation Evaluation]
The permeability of a porous medium to a specific fluid, when that fluid is the only fluid present. Permeability is defined as a property of the porous medium. However, the permeability measured on samples often depends on the fluid used. For example, liquids can affect the permeability through fines movement and clay alteration; gas permeability depends on slippage and inertial resistance, unless fully corrected for these effects. It is therefore more correct to talk of specific permeability to a particular fluid, although, in practice, the shorter term, permeability, is common.
