3.Relative permeability In presence of more than one fluid in the rock,the ratio of effective permeability of any phase to the absolute permeability of the rock is known as the "relative"permeability (kr)of that phase. For example,the relative permeability of the oil, gas,and water would be Kro=Ko/K,Krg =Kg/K Kw =Kw/K respectively.3. Relative permeability In presence of more than one fluid in the rock, the ratio of effective permeability of any phase to the absolute permeability of the rock is known as the "relative" permeability (kr) of that phase. For example, the relative permeability of the oil, gas, and water would be Kro = Ko/K, Krg = Kg/K, Kw =Kw/K respectively