The presence of asphaltenes and its tendency to form aggregates play a fundamental role on the high viscosity observed for heavy and extra heavy crude oils (H/XH). It has been shown that by removing the asphaltenes, a reduction of two to three orders of magnitude on the viscosity of the deasphalted product is obtained. It has also been demonstrated that asphaltenes interact extensively within themselves and with other similar molecules forming extended networks. By this way, the asphaltene solutions have relatively high viscosities and, these values increase exponentially with the concentration. In this work, the viscosity of H/XH is reduced by the use of additives that can act as modifiers of the aggregation behavior of asphaltenes. Several commercially available additives were evaluated at high (0.1-3%) and low (50 up to 400 ppm) concentrations at laboratory (20 mL) and bench (8 L) scales. For an extra heavy crude oil/diluent blends (75/25 wt.), the presence of the additives led to viscosity reductions up to 18 to 25% with respect to the blend without additives. Particle size measurements indicated that the presence of the Asphaltene Modifiers shifted the asphaltene distributions from “flocculated” (>1 μm) to “stabilized” asphaltenes (~0.1 μm) and give evidence of the effect of these additives on the aggregation behavior of asphaltenes. The commercial applications of these additives are also discussed.
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