Asphaltene is a complex macromolecule whose abundance strongly affects the physical and interfacial properties of crude oil. Asphaltene molecules may precipitate during crude oil production/transportation, which may lead to plugging/ clogging of wellbores, pipelines, and equipment. In this study, the solubility of asphaltene in toluene has been investigated by calculation of noncovalent interaction energies between asphaltenes in toluene medium. The results of this study revealed that the main interactions in the asphaltene−toluene system are Lifshitz−van der Waals and Lewis acid−base interactions, whereas the electrostatic double layer is of lower comparative order of significance specifically at lower separation distances and lower ζ potentials. However, the repulsive electrostatic double-layer interactions may assist in stabilizing the asphaltene−toluene system based on the comparative values of Lifshitz−van der Waals, Lewis acid−base, and electrostatic double-layer interactions. This is the case especially at higher separation distances and/or higher temperatures where asphaltene particles have greater values of ζ-potential. Furthermore, it is illustrated that when asphaltene has a lower electron-donor parameter, i.e., a lower basicity than toluene, then Lewis acid−base interactions between asphaltenes in toluene are repulsive. This repulsive Lewis acid−base interaction may compensate for the attractive van der Waals interactions between asphaltene particles at low asphaltene basicity. Finally, the electron donor/ acceptor component of the surface energy strongly determines the fate of asphaltene in crude oil colloidal system.

This study aims to theoretically investigate the performance of an ionic liquid-based hydrophobic deep eutectic solvent (HDES), methyltrioctylammonium chloride:glycerol (1:2), as an asphaltene deposition inhibitor. To do so, the concept of surface energy was implemented by applying the extended DLVO (Derjaguin–Landau–Verwey–Overbeek) theory. Accordingly, the impact of surface energy components in terms of electrostatic (EL), acid–base (AB), Lifshitz–van der Waals (LW), and Brownian (Br) interactions on the deposition process has been examined. In addition, the works of cohesion and adhesion between different interacting bodies involved in the deposition process have been determined. The results revealed that AB interactions played an essential role in the inhibition of asphaltene deposition by reducing the propensity of asphaltene toward the dolomite surface. The total interaction energy also showed that the presence of HDES would take the interaction energy of asphaltene-dolomite from attraction toward the repulsive state as much as 125%. Furthermore, the calculated works of cohesion/adhesion proved that the addition of HDES to the model oil could retard asphaltene particles’ cohesion, thus preventing them from aggregation and subsequent deposition onto the dolomite surface. It was also shown that HDES, dissolved in the model oil, would primarily be attracted by asphaltene rather than its own molecules, hence producing HDES-asphaltene conjugates in the medium. Finally, the lower affinity of asphaltenes toward the dolomite surface in the presence of HDES was confirmed using the work of adhesion. The theoretical approach, proposed in this study, can provide a guideline to evaluate the intermolecular interactions between interacting bodies during the asphaltene deposition process, including asphaltene, inhibitor, reservoir rock, and oleic medium.

An optimal reactor design is proposed that simultaneously improves the naphtha reforming reactor performance and increases sulfur trioxide production. In this new configuration, the naphtha reforming process as an endothermic reaction is coupled with the oxidation reaction of sulfur dioxide, which is an exothermic reaction. The differential evolution optimization technique is applied to maximize the produced amounts and yields of aromatics and hydrogen. The results obtained with the optimized thermally coupled reactor are compared with those of the conventional and thermally coupled reactors, proving the superiority of the proposed configuration.

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An interaction energy model is employed to discern the roles of liquid composition and asphaltene properties on asphaltene stability. The model determines Lifshitz-van der Waals (LW) and acid-base (AB) for two asphaltenes of A and B types with different polarities and synthetic oils with different nC 7 volume fractions. The results indicate that the liquid loses its solubility with increased nC 7 volume fraction, due to the reduction in its electron donor component. Moreover, at the very beginning of nC 7 addition, both asphaltenes show a similar resistance against aggregation, due to the similar rates of change in their LW and AB interaction energies. However, at latter stages of nC 7 addition, the two asphaltenes tend to have different precipitation propensities, which is consistent with the results of UV-vis measurements.

Fluid flow inside heterogeneous structure of dual porosity reservoirs is presented by two coupled partial differential equations (PDE). Finding an analytical solution for the diffusivity equations is tedious or even impossible in some circumstances due to the heterogeneity of dual porosity reservoirs. Therefore, in this study, orthogonal collocation method (OCM) is proposed for solving the governing equations in dual porosity reservoirs with constant pressure outer boundary. Since no analytical solution has been proposed for this system, validation is carried out by comparing the OCM-obtained results for “dual porosity reservoirs with circular no-flow outer boundary” with both exact analytical solution and real field data. Sensitivity analyses reveal that the OCM with 13 collocation points is a good candidate for prediction of pressure transient response (PTR) in dual porosity reservoirs. OCM predicts the PTR of a real field draw-down test with an absolute average relative deviation (AARD) of 0.9%. Moreover, OCM shows a good agreement with the analytical solution obtained by Laplace transform (AARD = 0.16%). It is worth noting that OCM requires a smaller computational effort. Thereafter, PTR of dual porosity reservoirs with a constant production rate in the wellbore and constant pressure outer boundary is simulated by OCM for wide ranges of operating conditions. Accuracy of OCM and its low required computational time justifies that this approximate method can be considered as a practical candidate for pressure transient analysis in dual porosity reservoirs.

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