Characterisation of Asphaltenes and Modelling of Flocculation – State of the Art

Pina, A.; Mougin, Pascal; Béhar, E.

doi:10.2516/ogst:2006037a

Cited by 53 publications

(40 citation statements)

References 110 publications

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“…The titration experiments were performed to determine the precipitation detection point, defined as the minimum vol % of precipitant needed to precipitate asphaltenes from oil in a time period less than 5 min after the addition of heptane. 52,53 Optical microscopy was used to determine the detection point when the size of aggregated asphaltenes becomes large enough to be detected by the technique (approx. 0.5 μm).…”

Section: Experimental Methodsmentioning

confidence: 99%

Structure of Asphaltenes during Precipitation Investigated by Ultra-Small-Angle X-ray Scattering

2018

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Time-resolved size and structure measurements of asphaltenes while in the process of precipitating were monitored for the first time using ultra-small-angle X-ray scattering. The results revealed that asphaltenes precipitating from a heptane-toluene mixture demonstrate a hierarchical structure of an asphaltene-rich phase (e.g., droplet) that further agglomerates into fractal flocs. The fractal flocs that form by the agglomeration of the asphaltene-rich phase are what is commonly detected by optical microscopy above the precipitation detection point. The surface of the asphaltene-rich phase is initially rough and transitions to a smooth interface, as would be expected for a highly viscous liquid. Simultaneous small-angle X-ray scattering measurements were also performed to investigate the structure of soluble asphaltenes, providing comprehensive structural characterization from the nanometer- to micrometer-length scales as a function of time. Further, the results demonstrate that the size and concentration of asphaltenes remaining in solution (e.g., soluble asphaltenes) do not change during precipitation, whereas the structure of insoluble asphaltenes varies. The ability to measure the properties of asphaltenes as they undergo precipitation opens new opportunities for understanding the fundamental mechanisms of asphaltene deposition and aggregation and the impact of chemical inhibitors to alter these processes. The universality of these conclusions and how specific properties vary as a function of asphaltene source and solution properties can provide valuable insight into asphaltene behavior.

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Section: Experimental Methodsmentioning

confidence: 99%

Structure of Asphaltenes during Precipitation Investigated by Ultra-Small-Angle X-ray Scattering

2018

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“…Parameters such as the nature of the precipitating solvent, the amount of solvent used, the contact time between oil and solvent and the temperature influence the composition of the extracted asphaltenes [1,31,32]. We therefore also studied the behavior of a model oil containing C7 asphaltenes.…”

Section: Comparison Between C5 and C7 Asphaltenesmentioning

confidence: 99%

Influence of pH on Oil-Water Interfacial Tension and Mass Transfer for Asphaltenes Model Oils. Comparison with Crude Oil Behavior

Hutin

Argillier

Langévin

2016

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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-Asphaltenes are shown to be amphoteric, containing acidic and basic species that can ionize at low and high pH respectively when they come in contact with water. We have used a mass transfer model in order to determine the partition coefficients of asphaltenes between oil and water. We have compared the influence of type of asphaltenes on interfacial tension and on mass transfer between oil and water and analysed the influence of an added surfactant. We have also compared the behavior of asphaltenes dissolved in model solvents with that of diluted heavy crude oils. Although asphaltenes qualitatively reproduce the behavior of crude oil components at the oil-water interface, differences were observed, either in interfacial tensions at low pH, or in partition coefficients at high pH. These differences are due to other molecules present in crude oil, which are either more interfacially active or more soluble in water.Résumé -Influence du pH sur la tension interfaciale et les transferts de masse pour des huiles modèles d'asphaltènes. Comparaison avec le comportement du brut -Nous avons mis en évidence le comportement amphotère des asphaltènes, qui contiennent des espèces acides et basiques pouvant s'ioniser lorsqu'ils entrent en contact avec l'eau. Nous avons utilisé un modèle de transfert de masse afin de déterminer les coefficients de partage des asphaltènes entre l'huile et l'eau. Nous avons comparé l'influence du type d'asphaltènes sur la tension interfaciale et le transfert de masse entre l'eau et l'huile, et analysé l'influence d'un tensio-actif ajouté. Nous avons également comparé le comportement des asphaltènes dissous dans des solvants modèle avec celui d'un brut lourd dilué. Bien que les asphaltènes reproduisent qualitativement le comportement du brut dilué à l'interface huile-eau, des différences sont observées entre les tensions interfaciales à bas pH bas, et dans les coefficients de partage à pH élevé. Ces différences sont dues à d'autres molécules présentes dans le brut, qui sont soit plus interfacialement actives, soit plus solubles dans l'eau.

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“…nC 5 or nC 7 ) at standard lab conditions. The majority of the previous works on thermodynamics of asphaltene stability are based on the assumption that asphaltene destabilization is an instantaneous phenomenon and the kinetics effects associated with asphaltene precipitation and aggregation have not been considered . The many experiments reported to date indicate that asphaltene aggregation is a gradual and time‐dependent process that occurs very slowly …”

Section: Introductionmentioning

confidence: 99%

“…The majority of the previous works on thermodynamics of asphaltene stability are based on the assumption that asphaltene destabilization is an instantaneous phenomenon and the kinetics effects associated with asphaltene precipitation and aggregation have not been considered. [19][20][21][22][23] The many experiments reported to date indicate that asphaltene aggregation is a gradual and time-dependent process that occurs very slowly. [12,17,24] While field experiences and laboratory studies demonstrate the effects of changes in pressure and oil composition on asphaltene destabilization, the effect of temperature, especially in live oils (live oils contain dissolved gases which are held by high reservoir pressure), is not well understood.…”

Section: Introductionmentioning

confidence: 99%

On the effect of temperature on precipitation and aggregation of asphaltenes in light live oils

et al. 2016

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Asphaltene precipitation and deposition is a serious issue in all facets of petroleum production and processing. Despite the numerous experimental efforts concerning asphaltenes, the effect of temperature on asphaltene precipitation and aggregation in live oils remains still an elusive and controversial subject in the available literature. In this work, a series of high pressure-high temperature depressurization experiments were designed to assess the effect of temperature on asphaltene precipitation and aggregation in light live oils. Asphaltene related experiments were performed using high pressure microscope and high pressure-high temperature filtration setup on a light live oil with low asphaltene content and a high potential of asphaltene formation. The results of the experiments were interpreted in terms of asphaltene onset pressure, size distribution and average diameter of the aggregates, fractal dimension of the asphaltene aggregates, and the amount of precipitated asphaltene. It was found that depressurization process at higher temperatures results in higher asphaltene onset pressure or earlier formation of the asphaltenes. Visualization experiments showed that asphaltene aggregates in light live oil are pressure-temperature fractal structures. Depressurization process at lower temperatures led to the formation of highly porous and loose aggregate structures with relatively low fractal dimensions. As the temperature of the depressurization process decreases the mechanism of asphaltene aggregation changes gradually from reaction limited aggregation to diffusion limited aggregation. This research reveals that temperature has crucial effects on asphaltene aggregation process in light live oils at elevated pressures which is of great importance for asphaltene handling and separation. This article is protected by copyright. All rights reserved

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Characterisation of Asphaltenes and Modelling of Flocculation – State of the Art

Cited by 53 publications

References 110 publications

Structure of Asphaltenes during Precipitation Investigated by Ultra-Small-Angle X-ray Scattering

Structure of Asphaltenes during Precipitation Investigated by Ultra-Small-Angle X-ray Scattering

Influence of pH on Oil-Water Interfacial Tension and Mass Transfer for Asphaltenes Model Oils. Comparison with Crude Oil Behavior

On the effect of temperature on precipitation and aggregation of asphaltenes in light live oils

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