Aromatic Polyisobutylene Succinimides as Viscosity Reducers with Asphaltene Dispersion Capability for Heavy and Extra-Heavy Crude Oils

Four aromatic polyisobutylene succinimides were synthesized and evaluated as viscosity reducers for heavy and extra-heavy Mexican crude oils. Because of the asphaltenic character of Mexican crude oils, aromatic heads capable of interacting with asphaltene aggregates by pi-pi stacking, hydrogen-bond formation, and acid-base interactions were selected. Asphaltene dispersion-aggregate inhibition and asphaltene disaggregation effects were evaluated as promoters of the viscosity reduction effect in asphaltenic crude oils, the asphaltene disaggregation being dominant. Chemical compounds show good efficiency as asphaltene aggregation inhibitors and dispersants and as viscosity reducers. Higher efficiency than the dilution effect induced by the solvent carrier is observed. Both experiments were studied by theoretical DFT calculations. Because of the agreement between theoretical and experimental results, both mechanisms can be elucidated. Results also show that the initial asphaltene content in oils is an important parameter in the selection of chemical agents as viscosity reducers.