Statistical analysis on parameters that affect wetting for the crude oil/brine/mica system

The crude oil properties governing the wettability of crude oil and brine on mica were investigated. Deposition of polar asphaltenes from oil causes mineral wetting to alter from strongly water-wet to less water-wet. The degree of alteration depends on the hydrophobicity of asphaltene and the amount of deposition, which depends on factors such as asphaltene content and solvency of the oil, acid and base content of the oil, brine pH and salinity, aging condition, and mineral type. Physico-chemical properties of the constituent phases that affect mineral wetting were examined. An adhesion test was applied to test water film stability governed by electrostatic interactions between oil/water and water/mineral interfaces. The effect of asphaltene solvency of oil on adhesion was also demonstrated. Statistical analysis was performed on the parameters affecting wettability. When the candidate parameter set was properly chosen, two dominant factors (asphaltene content and base number/acid number) that affect wetting emerge from the analysis. The correlation trend from statistical analysis is consistent with the knowledge and experience obtained from past and current wettability studies. (C) 2002 Elsevier Science B.V. All rights reserved.