Asphaltene Aggregation and Assembly Behaviors in Organic Solvents with Water and Inhibitor

Abstract

Asphaltenes cause problems such as emulsion formation and deposition/precipitation during crude oil production, processing, and transport. A deeper understanding of the behaviors of asphaltenes is needed to design remediation treatments to minimize costs during production. In this study, the aggregation and assembly behaviors of asphaltene model compound C5PeC11 under different conditions were studied and visualized through molecular dynamic simulations. C5PeC11 aggregates were formed as a result of the competition between the solvation of C5PeC11 in solvents and the self-association of C5PeC11 molecules. One-dimensional bent linear assembly of C5PeC11 aggregates was observed upon the addition of nheptane to toluene. Although the water content was low, the addition of water molecules resulted in enhanced C5PeC11 aggregation and considerably different C5PeC11 aggregate assembly behaviors. C5PeC11 aggregates formed a cluster in a parallel horizontal connection manner with the hydrocarbon tails located outside and polar groups located inside. The network formed via the hydrogen bonding between C5PeC11 and water as well as between water molecules provided new binding interactions for C5PeC11 aggregates. Water molecules were indispensable for the formation and retention of a C5PeC11 aggregate cluster. Dodecylbenzene sulfonic acid (DBSA) and water competed with each other to influence asphaltene associations when they were both present in the system. Both the hydrogen bonding between C5PeC11 and water and hydrogen bonding between water molecules contributing to the development of the network were hindered by DBSA. DBSA molecules succeeded in stabilizing C5PeC11 even in the presence of water molecules.

Molecular Mechanisms of Suppressing Asphaltene Aggregation and Flocculation by Dodecylbenzenesulfonic Acid Probed by Molecular Dynamics Simulations

“…All simulations were performed using the GROMACS 5.1.2 software package following the procedures stated in previous papers. ,,,− For each compound, CH 2 and CH 3 groups on the aliphatic chains were modeled using the united atom model, whereas the carbons in the polyaromatic rings were modeled as sp 2 hybridized carbons. , The force field parameters, generated using an Automated Topology Builder and a Repository server (version 2.2) based on GROMOS96, are shown in Tables S1 and S2. It should be pointed out that appropriate improper dihedrals were included to guarantee the plane structure of polyaromatic rings and to ensure the correct tetrahedral structure of united sp 3 hybridized carbon atoms.…”

Asphaltenes, subfractions A1 and A2 aggregation and adsorption onto RH-SiO2 nanoparticles: Solvent effect on the aggregate size

“…Likewise, a correspondence was observed by molecular dynamics simulations with the size of the aggregates obtained in the solutions being o-xylene > m-xylene > p-xylene ≈ benzene, which corresponds to the dipole moment and the solubility parameter due to the location of the -CH 3 substituent. Jiang et al [24] studied the aggregation behavior of a model polyaromatic asphaltene compound was evaluated. When heptane was added to a solution of the model in toluene, it increased the aggregation especially due to the possibility of establishing interactions via van der walls.…”