WETTABILITY EFFECTS ON SCALING 2-FLUID AND 3-FLUID CAPILLARY PRESSURE-SATURATION RELATIONS

Capillary pressure (P-c) - saturation (S) relationships for porous media containing three fluids are often predicted from two-fluid P-c-S curves. This practice was investigated for porous media with different wettabilities. Two- and three-fluid P-c-S curves were measured, using an automated setup, for sands containing air and water; air and oil, oil and water, and air, oil, and water. Similar P-c-S curves were found for air-oil systems while differences occurred for air-water or oil-water due to differences in hydrophobicity and contact angle hysteresis, Three-fluid P-c-S curves could be accurately predicted for hydrophilic media from two-fluid P-c-S data with scaling, using fitted contact angles and measured interfacial tensions, and Leverett's assumption. Such predictions were found to be inadequate for hydrophobic media because the intermediate fluid is presumably discontinuous.