Adsorption of Asphaltenes and Water on Reservoir Rock Minerals

Abstract

Abstract New data relating to the adsorption of asphaltenes on reservoir rock minerals are reported. The data were obtained by contacting samples of several different clay mineral types, as well as of Berea sandstone, with toluene solutions of a petroleum asphaltene fraction. This material was recovered from a deposit on the tubing string of a producing well. It was characterized with respect to molecular weight and elemental composition. Adsorption isotherms were determined and found to be of the Langmuir type, indicating monolayer adsorption. For each of the samples an independent surface area measurement was made. This permitted the probable size of the adsorbed asphaltene particles to be estimated. The effect of water on the adsorption of asphaltenes on kaolinite was also determined. It was found that adsorption was reduced but not eliminated by the presence of water. In these experiments the water was either pre-adsorbed on the clay or simply dissolved in the solvent. The amount of co-adsorbed water corresponded to 30-50 monolayers, indicating the probable formation of liquid bridges of water between clay particles. Estimates were obtained for the magnitude of the microscopic toluene/water contact angles which characterize these liquid bridges.