Asphaltenes, the most aromatic of the heaviest components of crude oil, are critical to all aspects of petroleum use, including production, transportation, refining, upgrading, and heavy-end use in paving and coating materials. As such, efficiency in these diverse disciplines mandates proper chemical accounting of structure−function relations of crude oils and asphaltenes, the vision of petroleomics (Asphaltenes, Heavy Oils and Petroleomics; Mullins, O. C., Sheu, E. Y., Hammami, A., Marshall, A. G., Eds.; Springer: New York, 2007). Indeed, the molecular characterization of asphaltenes is required as well as the detailed understanding of the hierarchical colloidal structures of asphaltenes and petroleum. With great prescience, Professor Teh Fu Yen and co-workers proposed a hierarchical model of asphaltenes to account for many of their characteristics known at that time (Dickie, J. P.; Yen, T. F. Macrostrucutres of asphaltic fractions by various instrumental methods. Anal. Chem. 1967, 39, 1847−1852). This m...

The Modified Yen Model

The Yen–Mullins model, also known as the modified Yen model, specifies the predominant molecular and colloidal structure of asphaltenes in crude oils and laboratory solvents and consists of the following: The most probable asphaltene molecular weight is ∼750 g/mol, with the island molecular architecture dominant. At sufficient concentration, asphaltene molecules form nanoaggregates with an aggregation number less than 10. At higher concentrations, nanoaggregates form clusters again with small aggregation numbers. The Yen–Mullins model is consistent with numerous molecular and colloidal studies employing a broad array of methodologies. Moreover, the Yen–Mullins model provides a foundation for the development of the first asphaltene equation of state for predicting asphaltene gradients in oil reservoirs, the Flory–Huggins–Zuo equation of state (FHZ EoS). In turn, the FHZ EoS has proven applicability in oil reservoirs containing condensates, black oils, and heavy oils. While the development of the Yen–Mullin...

Advances in Asphaltene Science and the Yen–Mullins Model

Each different molecular elemental composition—e.g., CcHhNnOoSs—has a different exact mass. With sufficiently high mass resolving power (m/Δm50% ≈ 400,000, in which m is molecular mass and Δm50% is the mass spectral peak width at half-maximum peak height) and mass accuracy (<300 ppb) up to ≈800 Da, now routinely available from high-field (≥9.4 T) Fourier transform ion cyclotron resonance mass spectrometry, it is possible to resolve and identify uniquely and simultaneously each of the thousands of elemental compositions from the most complex natural organic mixtures, including petroleum crude oil. It is thus possible to separate and sort petroleum components according to their heteroatom class (NnOoSs), double bond equivalents (DBE = number of rings plus double bonds involving carbon, because each ring or double bond results in a loss of two hydrogen atoms), and carbon number. “Petroleomics” is the characterization of petroleum at the molecular level. From sufficiently complete characterization of the organic composition of petroleum and its products, it should be possible to correlate (and ultimately predict) their properties and behavior. Examples include molecular mass distribution, distillation profile, characterization of specific fractions without prior extraction or wet chemical separation from the original bulk material, biodegradation, maturity, water solubility (and oil:water emulsion behavior), deposits in oil wells and refineries, efficiency and specificity of catalytic hydroprocessing, “heavy ends” (asphaltenes) analysis, corrosion, etc.

https://www.pnas.org/content/pnas/105/47/18090.full.pdf

Petroleomics: Chemistry of the underworld

Asphaltene adsorption at solid surfaces is a ubiquitous phenomenon that begins within the production well and continues through the entire production chain. It is generally an undesirable phenomenon that causes damage within reservoirs, fouling of pipelines and transportation equipment, and fouling of refining and upgrading equipment. However, by virtue of this phenomenon, problematic asphaltenes may also be selectively removed from petroleum streams to produce partially upgraded petroleum, which has significantly improved handling, processing, and upgrading qualities. This review covers many basic aspects regarding the chemical and physical nature of asphaltenes and sorbents related to asphaltene adsorption.

Asphaltene Adsorption, a Literature Review

https://www.ceaa-acee.gc.ca/050/documents_staticpost/59540/82534/Naphthenic_Acids_article.pdf

Naphthenic acids and other acid-extractables in water samples from Alberta: what is being measured?

Asphaltenes are known to deposit in both the petroleum recovery and topside refining processes. The asphaltenes are normally in equilibrium under reservoir conditions. As crude oil is produced, tha...

Mass Spectral Analysis of Asphaltenes. II. Detailed Compositional Comparison of Asphaltenes Deposit to Its Crude Oil Counterpart for Two Geographically Different Crude Oils by ESI FT-ICR MS

Asphaltenes are typically defined by their solubility in benzene and insolubility in pentane or heptane. They are believed to exist in petroleum crude oil as a colloidal suspension, stabilized by surface-adsorbed resins. Their normal equilibrium under reservoir conditions may be disrupted during production by pressure reduction, crude oil chemical composition changes, introduction of miscible gases and liquids, and mixing with diluents and other oils, as well as by acid stimulation, hot oiling, and other oilfield operations. Electrospray ionization preferentially ionizes polar N-, S-, and O-containing compounds, and its combination with ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry makes a powerful tool for the compositional analysis of petroleum-derived materials such as asphaltenes. In this work, we compare the compositional differences between heptane-precipitated asphaltenes and asphaltenes collected by live oil depressurization. Negative- and positive-ion electrospr...

Mass Spectral Analysis of Asphaltenes. I. Compositional Differences between Pressure-Drop and Solvent-Drop Asphaltenes Determined by Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Structural and compositional characterization of asphaltenes that were extracted from unstable crude oils, stable crude oils, and organic solid deposits was performed to elucidate their similarities and differences. A fractionation technique that divided the asphaltenes into different subfractions, based on polarity, was used to characterize these asphaltene samples. The parameters affecting the stability of these asphaltene subfractions were elucidated. The asphaltenes that were extracted from unstable crude oils and from solid deposits contained substantially greater portions of the higher polar fractions and have a higher polarity, compared to the asphaltenes obtained from crude oils with no asphaltene stability problems in the field. The dielectric constant, solubility, and flocculation experiments showed that these higher-polarity fractions have a greater tendency to aggregate and are more difficult to remediate. These results suggested that the presence of a certain type of asphalteneparticularly, a...

Andrew Yen

Papers

Mass Spectral Analysis of Asphaltenes. II. Detailed Compositional Comparison of Asphaltenes Deposit to Its Crude Oil Counterpart for Two Geographically Different Crude Oils by ESI FT-ICR MS

Mass Spectral Analysis of Asphaltenes. I. Compositional Differences between Pressure-Drop and Solvent-Drop Asphaltenes Determined by Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Characterization of polarity-based asphaltene subfractions

Characterization of naphthenic acids in crude oils and naphthenates by electrospray ionization FT-ICR mass spectrometry

Evaluating Asphaltene Inhibitors: Laboratory Tests and Field Studies