Relative permeability data are essential for almost all calculations of fluid flow in porous media. In addition, water and oil relative permeability curves play important roles in characterizing the simultaneous two-phase flow in porous media and predicting the performance of displacement processes. In this work, a pore-scale study of two-phase relative permeability in mixed-wet heterogeneous porous media at different capillary pressure and flow rate is presented.

Multicomponent Johnson, Bossler and Naumann (JBN) method was employed to determine relative permeability using recovery, saturation and pressure results obtained from 3D Eclipse simulation model of a core sample. Mixed-wet states were created by altering the wettability of solid surfaces in contact with the non-wetting phase at the end of the unsteady-state simulation of initially water-wet porous media. JBN relative permeability results were compared to input relative permeability. The JBN results were found to match input data relative permeability especially at lower capillary pressure. The relative permeability of water in the mixed-wet porous media was found to decrease at lower to medium flow rates as water is pinned in smaller pore spaces leading to lower saturation and connectivity in wetting layers. Meanwhile, oil relative permeability increased due to higher connectivity and therefrom greater mobility. On the hand, oil relative permeability of in the mixed-wet porous media decreased at higher flow rates where water connectivity increased the relative permeability of water with increasing water saturation. A new JBN based model was developed to determine relative permeability and good matches were observed between the JBN calculated results and the input relative permeability. Therefore, the model can be utilized for various porous media applications at different wetting conditions.

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