Asphaltene aggregation and deposition in pipeline: Insight from multiscale simulation

Abstract

Understanding the colloidal structure of crude oil in pipeline is of great significance for finding effective solutions to remediate and prevent the aggregation and deposition of asphaltene during transport process. Here, combing large-scale structural-unit-based dissipative particle dynamics simulations and all-atom molecular dynamics simulations, the colloidal structure and interatomic interactions of crude oil in the pipeline are studied. The analysis of structural characteristics of asphaltene aggregates demonstrates that temperature, pressure, and flow speed jointly affect the colloidal structure of crude oil at mesoscopic level and the compactness of asphaltene aggregates at microcosmic level. By analyzing the mesoscopic structural properties of crude oil during transport and the microscopic interaction between crude oil and Fe2O3, the competitive adsorption of crude oil components on pipeline surface is demonstrated. We reveal that although the fluid movement of crude oil is favorable for structural transformation of asphaltene aggregate from large size to small size in bulk phase, but the asphaltenes are steadily deposited onto pipeline surface with the exfoliation of other oil components. These findings provide a molecular-level understanding of the colloidal structure of asphaltene during transport of crude oil through pipeline.