Reconstruction of a Synthetic Crude Oil Using Petroleomics and Molecular Dynamics Simulations: A Multistructural Approach to Understanding Asphaltene Aggregation Behavior

Abstract

This study focuses on evaluating the differences between describing the asphaltene fraction using a unique average molecular structure compared to a multistructural approach by examining its effects on aggregation behavior using molecular dynamics (MD). Three asphaltene representations were considered: a hydrocarbon skeleton (without heteroatoms), a single average asphaltene molecular structure (with heteroatoms), and a multistructural approach (several molecular structures with different characteristics and heteroatom contents). Representative aromatic and resin molecules were also employed to describe the maltene content. In total, four systems were evaluated by MD simulations: the three asphaltene representations dissolved in Heptol-50 (1:1 mixture of n-heptane and toluene) at a concentration of 7 wt %, as well as the multistructural representation of asphaltenes dissolved in its respective maltene. Asphaltene aggregation behavior was assessed by using the radial distribution function (RDF), the asphaltene− asphaltene interaction energies, and the size distribution of the asphaltene aggregates. Our results showed that a multistructural approach to describing asphaltenes could more accurately reproduce the elemental analysis data than the conventional unistructural approach. In addition, the size of the asphaltene aggregates was found to double when a multistructural representation was used compared to a unistructural approach. Furthermore, heteroatom content increased the average size of the asphaltene aggregates by a factor of 1.5. Interestingly, maltenes reduced aggregate sizes by a factor of 0.4, presumably due to the role of the resins and the structure of the aromatic compounds proposed for the synthetic crude oil. Consequently, this study presents a promising approach to describe the complexity of oil by using a multistructural representation of the asphaltenes, which can be extensively implemented in molecular dynamics studies.

Structural-Compositional Effect of Polycyclic Aromatic Hydrocarbons on Thermal-Oxidative Decomposition at High-Pressure: A Molecular Dynamics and Machine Learning Approach

“…The increasing energy demand has resulted in the increased production of heavy and extra-heavy crude oils in recent years . This type of crude oil contains polycyclic aromatic hydrocarbons (PAHs) of higher molecular weight and complexity , compared to light crude oil; , its combustion products are consequently more harmful and polluting . The increasing use of such crude oils has thus had a strong impact on PAH concentrations in food, soil, air, sediments, water sources, sludge, and waste. , PAHs have a strong negative impact on humans and the environment and are considered to be carcinogenic .…”

New insight into the role of the self-assembly of heteroatom compounds in heavy oil viscosity enhancement

“…This observation highlights the crucial role of heteroatoms in bridging molecular moieties, as heteroatom-containing compounds contribute to a more intricate structure of asphaltene. 55 These heteroatom-containing compounds play an irreplaceable role in the aggregation structure of heavy oil molecules. The dynamic properties of polymers serve as a crucial metric for evaluating the efficacy of oil displacement.…”

A Review of Oil–Solid Separation and Oil–Water Separation in Unconventional Heavy Oil Production Process

“…The molecular structure of asphaltene has been the subject of many research studies [81][82][83][84][85]. In early works, two dominant structure models were accepted to describe the molecular structure of the asphaltene: namely, the "island" and the "archipelago" models [86,87].…”