Kinetics of asphaltene aggregation in toluene-heptane mixtures studied by confocal microscopy

The kinetics of asphaltenes in crude oils of different stability was studied by confocal microscopy. The physical nature of flocculated asphaltenes of Boscan and Furrial crude oils is shown through of high-resolution micrographics image, and their colloidal structural evolutions are described by an analysis of size distribution of flocculated asphaltenes particles. Two different behaviors associated with the crude oil stability were found. The size aggregates increase rapidly at the first time of the flocculation for a stable crude oil such as the Boscan and gradually for the Furrial crude oil, which is known as a crude oil of low stability. The results obtained demonstrate that the aggregation process of Boscan crude oil is initially determined by the diffusion of the aggregates by the attractive interactions between flocks and aggregate asphaltenes. On the other hand, the aggregation process of Furrial crude oil occurs in the initial stage due to the increment of the number of particles and not by the particle growth until reaching a limited one where the aggregation process becomes governed by the diffusion of colloid particles.