The effect of paraffinic fractions on crude oil wax crystallization

The influence of the concentration and type of paraffinic crude oil compone nts on the wax appearance temperature (WAT) was evaluated by means of Polar ized Light Microscopy. High pour point waxy crudes were doped with paraffin distillation cuts, and changes on cloud points permitted to assess the ine fficiency of a polymeric commercial paraffin inhibitor for crudes rich in h eavy paraffins. An insensitive crude oil upon the addition of wax inhibitor s was fractionated into its hydrocarbon type fractions. Light components we re distilled out as the C-24-constituents. C-24+ cyclo/iso and linear paraf fins were isolated from the distillation residue s saturates by means of 5 Angstrom molecular sieves adduction. The effect of virgin crude oil enrichm ent with the cyclo/isoparaffins fraction on its cloud point and a polymeric paraffin inhibitor efficiency were evaluated. These components have no sig nificant impact on the inhibitors efficiency at concentrations below 40 wt% , but they increase the crude oil cloud point above 50 wt%, as a consequenc e of the higher average molecular weight introduced by these components. At this high concentration, a crystal modifier activity enhancement was obser ved, probably caused by steric hindrance of naphthenic and branched structu res. The linear paraffin fraction with more than 24 carbon atoms (nC(24)+), also isolated from the virgin crud(: oil, was used for doping experiments on reconstituted crude samples, containing all the original components exce pt this particular fraction. A direct dependence between the cloud point an d the concentration of this fraction was assessed.