Determination of air and water relative permeability relationships for selected unconsolidated porous materials

The relationship between air-water relative permeabilities was investigated in a series of laboratory experiments using repacked Berino loamy fine sand and 30 mesh medium sand samples. The relative permeability curves demonstrated the classic characteristics reported for two phase immiscible flow. Factors affecting non-Darcian behavior in the air permeability were further studied for the Berino sand. Among these factors were slip flow effects and inertial effects and their relationship to liquid saturation. The magnitude of the observed slip was small and did not appear to be a function of saturation. However, the magnitude of the slip was dependent on the air pressure gradient for samples at intermediate saturations. Inertial effects became more apparent at relatively smaller pressure gradients and air fluxes as water saturation increased. The results indicate that, although these non-Darcian effects are small, they should be considered when interpreting air permeability measurements in unconsolidated materials