Dynamic phenomena controlling asphaltene aggregation and stabilization as observed by molecular simulations

Abstract

Coarse-grained molecular dynamics simulations were used to investigate the effect of molecular features (concentration and location of heteroatoms in asphaltene molecules), thermodynamic conditions (solvent composition, pressure, and temperature), and polydispersity on asphaltene aggregation and aggregate stability. The base case consisted of asphaltenes in the mixture toluene–methane (90:10 wt %) at reservoir conditions (160–170 atm and 400 K). The asphaltene mass fraction was 5 %. The dynamic behavior of the systems was monitored by tracking the number of molecules that form aggregates and those that remain as monomers as a function of time. We identified pressure and temperature as the conditions that affect asphaltene aggregation the most. In addition, the results underscore the importance of simulating polydispersed (i.e., heterogeneous) asphaltene systems to elucidate the role that small asphaltenes/resins play in asphaltene aggregation.