LAUSR

Abstract Separation of heavy hydrocarbons from mineral surfaces is highly dependent on the oil composition and their host rock surface properties. Herein, the petroleum is divided into SARA fractions (saturates, aromatics, resins, asphaltenes) to investigate their desorption behaviors on different types of mineral surfaces (silica (SiO 2 ), kaolinite (Al 2 Si 2 O 5 (OH) 4 ) and calcium carbonate (CaCO 3 )). The Quartz Crystal Microbalance with Dissipation (QCM-D) tests show that the saturates and aromatics could desorb from the mineral surfaces spontaneously even in water, while no desorption was observed for the asphaltenes and resins. Although the above desorption could be enhanced by alkaline or surfactant solutions, great difference still appears to different oil fractions. Oil characterization shows that the heavy fractions (i.e., asphaltenes, resins) possess richer acid groups than those of light fractions, allowing the stronger affinity of heavy fractions to the mineral surfaces through polar and chemical interactions. Additionally, the heavy fractions dominate in determining the desorption properties of bitumen (the mixed fractions), and lead to more significant wettability alteration to the mineral surfaces. Furthermore, the oil fractions desorption is also found to be highly influenced by the mineral types. Compared with silica, kaolinite has stronger affinity to the heavy oil fractions, leading to smaller amount of desorption. While on the calcium carbonate surface, less than 11% of the coated oil fractions are observed to be desorbed. Surface characterizations summarize that, due to the difference in mineral composition, the affinity of minerals to oil components in aqueous solutions is given as: calcium carbonate (positively charged calcium ions) > kaolinite (containing –AlOH, –SiOH groups and heavy metal elements) > silica (–SiOH group). The above results reveal the differences among bitumen subfractions and mineral types, allowing potential insights to the development of enhanced oil recovery, such as aqueous-nonaqueous hybrid extraction process, solvent extraction, CO 2 -enhanced oil recovery, etc.