De l'agrégation à la floculation des asphaltènes, une description structurale par diffusion de rayonnement

Abstract

The study, using radiation scattering techniques (X-rays, neutrons, light) of asphaltenes in toluene and heptane mixtures, reveals their structure of aggregation versus the heptane/toluene ratio. In a solvent containing little heptane, the aggregates of asphaltenes are fractal and solvated. Their kinetics of aggregation is compatible with the forecasts model of aggregation RLCA (Reaction Limited Cluster Aggregation). For higher proportions of heptane the asphaltenes arrange in compact structures of very big sizes. We associate this transition, between a solvated aggregation and a compaction process, to the asphaltene flocculation phenomenon. The study, using the very small angle Xray scattering technique, of the Safaniya vaccum residue shows that these compact asphaltene aggregates may exist in some industrial fluids.