The influence of the adsorption of amphiphiles and resins in controlling asphaltene flocculation

Amphiphiles are frequently used to prevent asphaltene precipitation in reservoir rocks and wellbore tubing. It is supposed that these substances can stabilize the asphaltenes forming a steric stabilization layer around them. In this study, adsorption isotherms of two amphiphiles (nonylphenol and nonylphenolic resin) and a native resin on asphaltene particles are obtained in order to analyze the relationship between adsorption and effectiveness of these compounds as asphaltene stabilizers. The comparison of the three isotherms reveals a significant difference between the adsorption behavior of the amphiphiles and the resin fraction in terms of the shape of the isotherm. Nonylphenol and nonylphenolic resin adsorption isotherms show an LS-shape that can be explained using an adsorption mechanism in two steps. The adsorption isotherm of the native resin can be explained by penetration of the micropores of the asphaltene particles by resin molecules. There were found significant differences in the activity of the studied compounds as asphaltene precipitation inhibitors that can be linked to the adsorption behavior of these species. In particular, the native resins seem to show an activity stabilization mechanism different than that found for the other species studied.