Simple Simulation Model for Exploring the Effects of Solvent and Structure on Asphaltene Aggregation.

Area of Science:

• Petroleum Science
• Computational Chemistry
• Materials Science

Background:

• Asphaltenes, defined by solubility, are complex crude oil components.
• The Yen-Mullins model describes asphaltene aggregation via nanoaggregates with stacked aromatic cores and aliphatic coronas.
• Understanding asphaltene self-assembly is crucial for petroleum processing and stability.

Purpose of the Study:

• To develop and utilize a coarse-grained (CG) model to investigate the physical mechanisms of asphaltene self-assembly.
• To explore the influence of solvent character and molecular structure on asphaltene aggregation.
• To validate the insights provided by the Yen-Mullins model through computational simulations.

Main Methods:

• Development of a coarse-grained model representing asphaltenes with united atom detail.
• Simulation of 147 asphaltene solutions under varying solvent conditions by modulating inter-group attractions.
• Analysis of aggregate formation, stacking interactions, and the role of aliphatic tails.

Main Results:

• The CG model accurately captures asphaltene shape and conformational properties.
• Island-type asphaltenes form stacked aggregates under conditions favoring aromatic interactions, consistent with the Yen-Mullins model.
• Nanoaggregation onset is independent of aliphatic tails, but tails can limit aggregate growth; enhanced interactions promote larger aggregates.
• Archipelago-type molecules form large aggregates without significant stacking.

Conclusions:

• The coarse-grained model effectively simulates the physical picture of the Yen-Mullins model for asphaltene aggregation.
• Solvent and molecular structure significantly impact asphaltene self-assembly, particularly aromatic interactions.
• The model provides a valuable tool for studying later stages of asphaltene aggregation and stability.