A property characterizing agility of the fluid -phase under pressure gradient with account of reservoir permeability and dynamic fluid viscosity:

M_\alpha(s) = \frac{k_\alpha}{\mu_\alpha} =   \frac{k_{air} \cdot k_{r \alpha}}{\mu_\alpha} = k_{air} \cdot M_{r\alpha}(s)

where

	formation permeability to fluid -phase
	dynamic viscosity of fluid -phase
	absolute permeability to air
	relative phase mobility
	relative formation permeability to fluid -phase
	reservoir saturation , -phase saturation

In most popular case of a 3-phase fluid model this will be:

See also