MODELING OF FLUID INTRUSION INTO POROUS MEDIA WITH MIXED WETTABILITIES USING PORE-NETWORK

Water or air intrusion into a porous medium filled with the other fluid is affected by many factors such as size, configuration, and connectivity of pores as well as the contact angle of grain. To deal with these pore-scale factors, a pore-network model is utilized. According to the modified Delaunay method, pore-networks are extracted from randomly packed spherical grains computed by the distinct element method. Displacement processes of two immiscible fluid in a porous medium with mixed wettabilities, are modeled in an invasion percolation manner, in which simultaneous invasion is allowed, and water retention curves in drainage and imbibition processes are computed. The results obtained show that hydrophobic grains do not have just a strong effect on the water retention properties, but also the amount of water/air residue after a drainage/imbibition process depends on the invasion rate.