Honarpour M., Koederitz L. Relative Permeability Of Petroleum Reservoirs

CRC Press. 1986. 152p.
The relative permeability of a rock to each fluid phase can be measured in a core sample by either steady-state or unsteady-state methods. In the steady-state method, a fixed ratio of fluids is forced through the test sample until saturation and pressure equilibria are established. Numerous techniques have been successfully employed to obtain a uniform saturation. The primary concern in designing the experiment is to eliminate or reduce the saturation gradient which is caused by capillary pressure effects at the outflow boundary of the core. Steady-state methods are preferred to unsteady-state methods by some investigators for rocks of intermediate wettability, although some difficulty has been reported in applying the Hassler steady-state method to this type of rock.In the capillary pressure method, only the nonwetting phase is injected into the core during the test. This fluid displaces the wetting phase and the saturations of both fluids change throughout the test. Unsteady-state techniques are now employed for most laboratory measurements of relative permeability. Some of the more commonly used laboratory methods for measuring relative permeability are described below.