Carbon K-edge X-ray Raman spectroscopy supports simple, yet powerful description of aromatic hydrocarbons and asphaltenes

Bergmann, Uwe; Groenzin, Henning; Mullins, Oliver C.; Glatzel, Pieter; Fetzer, John C.; Cramer, Stephen P.

doi:10.1016/s0009-2614(02)02003-1

Cited by 85 publications

(101 citation statements)

References 27 publications

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“…Recently, carbon x-ray Raman spectroscopy has been applied to asphaltenes. These results confirm that asphaltene aromatic carbon is pericyclic (Bergmann et al 2003;Bergmann and Mullins 2007). Calculations of x-ray Raman spectra support these findings (Gordon et al 2003).…”

Section: Asphaltene Chemical Moietiessupporting

confidence: 75%

Review of the Molecular Structure and Aggregation of Asphaltenes and Petroleomics

Mullins

2008

SPE Journal

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116

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Summary Tremendous strides have been made recently in asphaltene science. Many advanced analytical techniques have been applied recently to asphaltenes, elucidating many asphaltene properties. The inability of certain techniques to provide correct asphaltene parameters has also been clarified. Longstanding controversies have been resolved. For example, molecular structural issues of asphaltenes have been resolved; in particular, asphaltene molecular weight is now known. The primary aggregation threshold has recently been established by a variety of techniques. Characterization of asphaltene interfacial activity has advanced considerably. The hierarchy of asphaltene aggregation has emerged into a fairly comprehensive picture, essentially in accord with the Yen model with the additional inclusion of certain constraints. Crude oil and asphaltene science is now poised to develop proper structure-function relations that are the defining objective of the new field: petroleomics. The purpose of this paper is to review these developments in order to present a more clear and accessible picture of asphaltenes, especially considering that the asphaltene literature is a bit opaque. Introduction The asphaltenes are a very important class of compounds in crude oils (Chilingarian and Yen 1978; Bunger and Li 1981; Sheu and Mullins 1995; Mullins and Sheu 1998; Mullins et al. 2007c). The asphaltenes represent a complex mixture of compounds and are defined by their solubility characteristics, not by a specific chemical classification. A common (laboratory) definition of asphaltenes is that they are toluene soluble, n-heptane insoluble. Other light alkanes are sometimes used to isolate asphaltenes. This solubility classification is very useful for crude oils because it captures the most aromatic portion of crude oil. As we will see, this solubility defintion also captures those molecular components of asphaltene that aggregate. Other carbonaceous materials such as coal do possess an asphaltene fraction, but that often will not correspond to the most aromatic fraction. Petroleum asphaltenes, the subject of this paper, can undergo phase transitions that are an impediment in the production of crude oil. Fig. 1 shows a picture of an asphaltene deposit in a pipeline; obviously, asphaltene deposition is detrimental to the production of oil. Immediately it becomes evident that different operational definitions apply for the term asphaltene in the field vs. the lab. Indeed, the field deposit is very enriched in n-heptane-insoluble, toluene-soluble materials, but this field asphaltene deposit is not identically the standard laboratory solubility class. It is common knowledge that a pressure drop on certain live crude oils (containing dissolved gas) can cause asphaltene flocculation, the first step in creating deposits that are seen in Fig. 1. Highly compressible, very undersaturated crude oils are most susceptible to asphaltene deposition problems with a pressure drop (de Boer et al. 1995). In depressurization flocculation, the character of the asphaltene flocs is dependent on the extent of pressure drop, suggesting some variations in the corresponding chemical composition (Hammami et al. 2000; Joshi et al. 2001). Comingling different oils can result in asphaltene precipitation that can resemble solvent precipitation. Asphaltenes are hydrogen-deficient compared to alkanes; thus, either hydrogen must be added or coke removed in crude oil refining to generate transportation fuels. Thus, asphaltene content lowers the economic value of crude oil. Increasing asphaltene content is associated with dramatically increasing viscosity, especially at room temperature; again, this is of operational concern. The strong temperature dependence of viscosity of asphaltic materials is one of their important properties that make them useful for paving and coating; application of asphaltic materials is facile at moderately high temperatures, while desired rheological properties are obtained at ambient temperatures.

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Section: Asphaltene Chemical Moietiessupporting

confidence: 75%

Review of the Molecular Structure and Aggregation of Asphaltenes and Petroleomics

Mullins

2008

SPE Journal

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116

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“…NEXAFS data thus substantiate the idea that sulfur is in the form of organic functional groups such as thiophenes. The overlap of p * (C@C) transitions from different types of p-bonds with close absorption energies in macromolecular or polycyclic aromatic hydrocarbons (PAH) often results in a single composite absorption peak (Boyce et al, 2002;Myneni, 2002;Bergmann et al, 2003). In Type B globules, the large p * (C@C) peak centred at $285.6 eV ( Figs.…”

Section: Decomposition Of Nexafs Spectra and Assignment Of Absorptionmentioning

confidence: 99%

Organic matter heterogeneities in 2.72Ga stromatolites: Alteration versus preservation by sulfur incorporation

Lepot

Benzerara

Rividi

et al. 2009

Geochimica et Cosmochimica Acta

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“…X-ray Raman studies show that the type of aromatic carbon that dominates asphaltenes is the more stable "sextet" carbon and not the isolated double bond. 27 Chemical stability is not a surprising attribute of asphaltenes. However, nuclear magnetic resonance (NMR) studies indicated that substantially smaller PAHs dominated asphaltenes; 28 thus, uncertainty exists here and merits closer investigation.…”

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confidence: 99%

Advances in Asphaltene Science and the Yen–Mullins Model

et al. 2012

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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−Mullins model was founded on a very large number of studies, it nevertheless remains essential to validate consistency of this model with important new data streams in asphaltene science. In this paper, we review recent advances in asphaltene science that address all critical aspects of the Yen−Mullins model, especially molecular architecture and characteristics of asphaltene nanoaggregates and clusters. Important new studies are shown to be consistent with the Yen−Mullins model. Wide ranging studies with direct interrogation of the Yen−Mullins model include detailed molecular decomposition analyses, optical measurements coupled with molecular orbital calculations, nuclear magnetic resonance (NMR) spectroscopy, centrifugation, direct-current (DC) conductivity, interfacial studies, small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS), as well as oilfield studies. In all cases, the Yen−Mullins model is proven to be at least consistent if not valid. In addition, several studies previously viewed as potentially inconsistent with the Yen−Mullins model are now largely resolved. Moreover, oilfield studies using the Yen−Mullins model in the FHZ EoS are greatly improving the understanding of many reservoir concerns, such as reservoir connectivity, heavy oil gradients, tar mat formation, and disequilibrium. The simple yet powerful advances codified in the Yen−Mullins model especially with the FHZ EoS provide a framework for future studies in asphaltene science, petroleum science, and reservoir studies.

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Carbon K-edge X-ray Raman spectroscopy supports simple, yet powerful description of aromatic hydrocarbons and asphaltenes

Cited by 85 publications

References 27 publications

Review of the Molecular Structure and Aggregation of Asphaltenes and Petroleomics

Review of the Molecular Structure and Aggregation of Asphaltenes and Petroleomics

Organic matter heterogeneities in 2.72Ga stromatolites: Alteration versus preservation by sulfur incorporation

Advances in Asphaltene Science and the Yen–Mullins Model

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