Effects of asphaltene concentration and asphaltene agglomeration on viscosity

Li, Xingxun; Chi, Pengcheng; Guo, Xuqiang; Sun, Qiang

doi:10.1016/j.fuel.2019.115825

Cited by 54 publications

(32 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Shaw developed techniques that realize the separation of asphaltene nanoaggregates without solvent addition by using nanofilters, , which proposed a new method for understanding the components of crude oil by experimental methods. It has been confirmed that the high viscosity of heavy crude oil is related to the size of the nanoaggregate . As an example, when the volume fraction of asphaltenes remains constant, the viscosity of heavy oil samples decreases significantly as the temperature increases. , Molecular dynamics (MD) simulations show that the number of aggregated asphaltenes decreases as temperature increases, which is the main factor for the decrease in the viscosity of heavy crude oil .…”

Section: Introductionmentioning

confidence: 93%

“…Hemmati-Sarapardeh et al observed a slight increase in asphaltene aggregate size as the asphaltene concentration in toluene increased. Numerous attempts have been repeatedly made to find correlations between the asphaltene concentration and the viscosity of heavy oil. ,, In fact, a relative low asphaltene concentration also can cause severe deposition problems, and different asphaltene components do not contribute equally to aggregation and precipitation, which indicates the role of not only the concentration of asphaltenes but also their structures and compositions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Molecular Dynamics Simulation Reveals Unique Rheological and Viscosity–Temperature Properties of Karamay Heavy Crude Oil

Zhu

Zhang

et al. 2021

Energy Fuels

View full text Add to dashboard Cite

Heavy oil, with high viscosity and complex compositions, often faces a series of challenges in the process of its exploitation and utilization. There are huge amounts of compositions with different molecular structures in heavy oil, and it is a great challenge to clarify the influence of the microstructure of heavy oil on the rheological and viscosity–temperature properties. Based on the experimental data, such as acid value, element content, functional group type of the heavy oil, and so on, we constructed six types of heavy oils from three regions to reveal the unique properties of Karamay heavy oil. Molecular dynamics simulation was used to study the effects of the compositions and the aggregation structure on the rheological and viscosity–temperature properties of heavy oil. The results show that the rheological properties of Karamay heavy oil with low asphaltene concentration are dominated by molecular conformation, and heavy oil with molecules that are not easily stretched has a higher viscosity. When the concentration of asphaltene is high, the nanoaggregates formed by asphaltene molecules and their variation with shear rate affect the viscosity. Compared with the aggregates by the island structure asphaltene molecules, the larger nanoaggregate size of continental structure due to stronger π–π interaction leads to the increase in viscosity. However, the viscosity decreases faster with the increase in shear rate, which is attributed to the more orderly aggregate structure of polycondensed aromatic rings that can be easily pulled along the velocity plane. In addition, we found that metal ions, as a bridge, can interact with molecules containing different heteroatoms, forming larger clusters and increasing the viscosity of Karamay heavy oil. For the viscosity–temperature properties, the more intense thermal movement of molecules with the increased temperature weakens the interaction between the aromatic rings and decreases the viscosity of heavy oils.

show abstract

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation Reveals Unique Rheological and Viscosity–Temperature Properties of Karamay Heavy Crude Oil

Zhu

Zhang

et al. 2021

Energy Fuels

View full text Add to dashboard Cite

show abstract

“…Pueden obstruir el fondo del pozo y tuberías de producción y equipos de superficie (Alimohammadi, Zendehboudi & James, 2019). Durante el transporte de petróleo crudo, la precipitación y la deposición de asfaltenos pueden obstruir los oleoductos y asentarse en los buques cisternas (Li, Chia, Guoa & Sun, 2019). En las refinerías, los asfaltenos pueden depositarse en las columnas de destilación, ensuciar los intercambiadores de calor y también causar la desactivación de los catalizadores (Ghosh, Chaudhuri, Kumar & Panja, 2016).…”

Section: Introductionunclassified

Evaluación del aceite de Anacardium occidentale como inhibidor de floculación de asfaltenos

Tocuyo

Velásquez²

2020

View full text Add to dashboard Cite

En la investigación se evaluó, a nivel de laboratorio, al aceite de cáscaras de la semilla de Anacardium occidentale (CNSL), como inhibidor de floculación de asfaltenos. Se prepararon tres mezclas de CNSL en Diésel (40, 60 y 80% V/V) y se aplicaron cuatro dosis (2, 4, 6 y 8 µL) a 10 mL de una muestra de petróleo del Campo El Furrial, Venezuela, así como, el Diésel y el aceite puros, para un total de cinco productos evaluados a las cuatro dosis. Se midió como variable respuesta el Umbral de Floculación de los asfaltenos (UF), como el volumen de n-heptano aplicado al petróleo hasta observar en un microscopio óptico la formación de agregados. El diseño experimental fue factorial, con dos factores experimentales, Producto y Dosis y una variable respuesta UF, medida por triplicado para cada combinación producto-dosis. Se aplicó ANOVA factorial y test LSD de Fisher con α = 0,05. Se obtuvo que el umbral de floculación fue dependiente de los dos factores de forma significativa (p < 0,05) y la presencia del CNLS en la mezcla produce efecto inhibidor, con un máximo de eficiencia de 43,6% para el producto al 80% CNLS a la dosis de 4 µL/10mL de petróleo.

show abstract

“…1−3 It is widely accepted that asphaltenes have the highest polarity and molecular weight of petroleum components, consisting of a complex mixture of aromatic and naphthenic cores substituted with alkyl side chains. 4,5 There are also some heteroatoms, such as nitrogen (N), oxygen (O), and sulfur (S), located on the conjugated cores, as well as side chains. 3,6−8 The presence of asphaltenes in crude oil is crucial not only for oil recovery and transportation but also for refining or other petroleum utilization fields.…”

Section: Introductionmentioning

confidence: 99%

“…Asphaltenes are defined as the insoluble phase of oil in light paraffins, such as n -pentane or n -heptane, but the soluble phase in aromatic solvents, such as toluene or benzene. − It is widely accepted that asphaltenes have the highest polarity and molecular weight of petroleum components, consisting of a complex mixture of aromatic and naphthenic cores substituted with alkyl side chains. , There are also some heteroatoms, such as nitrogen (N), oxygen (O), and sulfur (S), located on the conjugated cores, as well as side chains. ,− The presence of asphaltenes in crude oil is crucial not only for oil recovery and transportation but also for refining or other petroleum utilization fields. Because of their special structures, asphaltenes tend to aggregate and form macrostructures, leading to a series of problems, such as an increased oil viscosity, precipitation, adsorption at solid surfaces, even halting fluid production, and so forth. ,,− Especially, serious coking in refining could be caused by asphaltene aggregation …”

Section: Introductionmentioning

confidence: 99%

Impact of Functional Group Methylation on the Disaggregation Trend of Asphaltene: A Combined Experimental and Theoretical Study

et al. 2019

View full text Add to dashboard Cite

Asphaltenes have a tendency toward aggregation, leading to a series of problems (e.g., coking) in the field of refining or other oil utilization and making the development of a disaggregation method an urgent need. We employed functional group methylation experiments combined with molecular dynamics simulations and quantum chemical calculations to reveal the disaggregation mechanism of asphaltenes based on the chemical alteration method. Here, the experimental results show that the intersheet distances in the asphaltene aggregate increase after the methylation reaction, and the asphaltene molecules are not prone to reaggregation after methylation, which was demonstrated by an increase in the critical aggregation concentration in toluene. These disaggregation effects can be explained by the theoretical study results; that is, they can be attributed to the reduction of the electrostatic interaction, which is derived from the disappearance of the hydrogen bonds after methylation. However, a thorough disaggregation cannot be achieved only by methylation because the van der Waals force is always the dominant force in both raw and methylated asphaltenes, outweighing the electrostatic force. Asphaltene molecules with very short side chains containing more than one terminal polar group could obtain a better disaggregation effect by the methylation reaction, whereas those with long chains could not. Our results provide the underlying insights for the proposal of an effective method for asphaltene disaggregation to prevent coking.

show abstract

Effects of asphaltene concentration and asphaltene agglomeration on viscosity

Cited by 54 publications

References 57 publications

Molecular Dynamics Simulation Reveals Unique Rheological and Viscosity–Temperature Properties of Karamay Heavy Crude Oil

Molecular Dynamics Simulation Reveals Unique Rheological and Viscosity–Temperature Properties of Karamay Heavy Crude Oil

Evaluación del aceite de Anacardium occidentale como inhibidor de floculación de asfaltenos

Impact of Functional Group Methylation on the Disaggregation Trend of Asphaltene: A Combined Experimental and Theoretical Study

Contact Info

Product

Resources

About