Some mathematical models for the flow of waxy crude oils

We present some recent models describing the flow of mineral oils with a high content of paraffin at temperature below the cloud point (i.e. the crystallization temperature of paraffin) and more specifically below the pour point at which the crystals aggregate and the oil takes a jel-like structure. From the rheological point of view such a system can be modelled as a Bingham fluid whose parameters evolve according to the volume fraction of crystallized paraffin and the aggregation degree of crystals. The problem is not studied in its full generality since a number of different situations can arise presenting various degrees of complexity. Therefore many questions remain open for further research.