Experimental study of the effect of wettability on the relative permeability for air–water flow through porous media

•The methodology presented in this work represents an interesting feature in the study of relative permeability.•We investigate the effect of changing the wettability condition of the glass beads on the relative permeability in a co-current air–water flow.•We found that when the surfaces become more hydrophobic, the water relative permeability increases significantly for all cases tested.•The effect is more pronounced when the pore size is smaller than the capillary length. A two-phase flow through porous media is studied experimentally. Considering a classical permeameter array, the value of permeability is obtained for cores made of nearly monodispersed spherical glass beads. In particular, we investigate the effect of changing the wettability condition of the glass beads on the relative permeability in a co-current air–water flow. We found that when the surfaces become more hydrophobic, the water relative permeability increases significantly for all cases tested. The effect is more pronounced when the pore size is smaller than the capillary length. Our measurements are in good qualitative agreement with some results in the literature. The increase of permeability resulting by the addition of a surface-modifying wetting agent could be of use for the secondary recovery of oil and gas in the petroleum industry.