Thermodynamic Model of Petroleum Fluids Containing Polydisperse Asphaltene Aggregates

Victorov, Alexey I.; Smirnova, N. A.

doi:10.1021/ie970869z

Cited by 23 publications

(11 citation statements)

References 39 publications

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“…Asphaltenes have been extensively studied (Acevedo et al, 1998(Acevedo et al, , 2007Adams, 2014;Al-Maamari and Buckley, 2003;Franco et al, 2013b;Mullins et al, 2007;Pacheco-Sa´nchez et al, 2003;Rahimi and Solaimany Nazar, 2009;Rastegari et al, 2004;Victorov and Smirnova, 1998), being the most polar oil fraction, with complex chemical structures with a low ratio of aliphatic/aromatic chains (Acevedo et al, 2007;Mullins, 1998Mullins, , 2011Mullins et al, 2007). Asphaltenes possess structures containing heteroatoms that allow self-aggregation, initially leading to colloidal aggregates, promoting the growth of the aggregates and consequently increasing the oil viscosity (Ghanavati et al, 2013;Leontaritis et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

RETRACTED: Striking behavior of the rheology in heavy crude oils by adding nanoparticles

Taborda

Franco

Ruiz

et al. 2017

Adsorption Science & Technology

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The main objective of this paper is to provide unexpected experimental evidence of heavy oil and extra-heavy crude oils viscosity reduction resulting from the presence of nanoparticles of different chemical natures (SiO 2 , Fe 3 O 4 , and Al 2 O 3), surface acidity, and concentration at low-volume fractions. The viscosity of the enhanced fluids was measured using a rotational rheometer at shear rates varying between 1 and 75 s À1. Upon addition of nanoparticles viscosity reduction was observed in all cases evaluated. However, the maximum viscosity reduction of roughly 52% was obtained at a concentration of 1000 mg/l with 7 nm SiO 2 nanoparticles at low shear rate, below 10 s À1 , contrary to expectations from Einstein's viscosity theory in particulate systems. A mathematical model based on a modification to Pal and Rhodes Model for viscosity of suspensions is proposed in this work. The said model was validated successfully using experimental data, as evidenced by root-mean-square error values lower than 10%. The importance of our findings lies in the lack of prior experimental and theoretical data in the open literature showing heavy crude oils viscosity reduction in the presence of nanoparticles.

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Section: Introductionmentioning

confidence: 99%

RETRACTED: Striking behavior of the rheology in heavy crude oils by adding nanoparticles

Taborda

Franco

Ruiz

et al. 2017

Adsorption Science & Technology

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“…So far many experimental evidence has been gathered in support of this theory (2). Measurements of the size and shape of the colloids have been reported, and some theoretical studies regarding phase behavior have used the colloidal approach (3)(4)(5). Undoubtedly, this interest is due to the negative impact of asphaltene precipitation during production and other industrial operations, and hence research in this area is very active.…”

Section: Introductionmentioning

confidence: 99%

New Techniques and Methods for the Study of Aggregation, Adsorption, and Solubility of Asphaltenes. Impact of These Properties on Colloidal Structure and Flocculation

Castillo

Fernández

Ranaudo

et al. 2001

Petroleum Science and Technology

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The solubility of Furrial asphaltene in toluene was 57g L −1 . However, using a new technique, based on the precipitation of this sample by the phenol PNP, we found that a fraction (2), comprising 47% of the asphaltene, is of low solubility. This suggested that this material constitutes the colloidal phase, and the rest acts as the dispersing fraction. This technique allowed the fractionation of asphaltenes in fractions A 1 , A 2 , and A 3 according to solubility, going from practically insoluble (A 1 ) to low (A 2 , 1 g L −1 ) to high (A 3 , around 57 g L −1 ). The adsorption isotherms of asphaltenes on glass and silica in toluene consist of a sequence of steps or step-wise adsorption. The first layer or first step is formed by the adsorption ORDER REPRINTS 76CASTILLO ET AL.of free asphaltene molecules and by small aggregates (aggregation number between 3 and 6) which saturate the glass or silica surface in the usual manner (L-type or H-type isotherms). However, we suggest that the second, third, and other asphaltene layers adsorb sequentially according to the above differences in solubility. The very slow changes with time and the negligible desorption from the surface measured for the above isotherms were interpreted as the effect of packing or the building up of a well packed layer. This would be achieved by the slow formation and rupture of bonds between neighboring molecules at the surface. Thus, molecules with difficulties to pack, adsorbed by a kinetically controlled process, are either rejected or relocated in a thermodynamic controlled process. The above results and ideas were used to improve the models for asphaltene and petroleum colloids and to underscore the importance of surfaces and colloid dispersants in asphaltene precipitation during the production of crude oils. For instance, the results described below suggest that colloids are constituted by a well packed and insoluble asphaltene core, impervious to the solvent, and by a loose packed periphery which, by allowing solvent penetration, keep the colloid in solution. According to this model, desorption of compounds in the above loosely packed periphery, such as the one promoted by a surface, would be the main cause of asphaltene precipitation from crude oils. In this case, solubility reductions caused by pressure drops during oil production would have a minor effect. Also, preliminary number average molecular weights M n for four asphaltenes, obtained using a new procedure, are presented here. The M n values obtained ranged from 780 to 1150 g/mol.

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“…Two examples are Nafion membranes 76 and asphaltenic aggregates in crude oil. 77 However, the discussion of these very specific topics is outside the scope of this review.…”

Section: Discussionmentioning

confidence: 99%

“…We note that a wider spectrum of soft mesostructured systems may be described with the aid of molecular thermodynamic models. Two examples are Nafion membranes and asphaltenic aggregates in crude oil . However, the discussion of these very specific topics is outside the scope of this review.…”

Section: Discussionmentioning

confidence: 99%

Molecular thermodynamics of soft self-assembling structures for engineering applications

Victorov

2015

J. Chem. Technol. Biotechnol.

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Controlling self‐assembly is a key issue in many applications such as encapsulation of drugs, micelle separation, and fabrication of nanoporous materials. For providing guidance to control self‐assembly, a reliable prognosis of aggregation behavior is indispensable. Molecular thermodynamic models have been developed for different types of soft mesoscale structures formed by aggregating chainlike amphiphilic molecules. Examples include nonionic and ionic copolymer gels swelling in selective solvents, surfactant micellar solutions and amphiphilic membranes. Though rather different in chemical nature and applications, these systems are all characterized by self‐assembly into soft mesoscale structures that are sensitive to external conditions or applied stimuli. The models predict a number of thermodynamic and structural characteristics (equilibrium size and stability of different morphologies, equilibrium swelling, elastic properties, solute partitioning, etc.) in terms of several adjustable parameters and molecular characteristics of components. Consideration of nanoscale morphology gives rise to interesting structure–property relations reflected by relatively simple models. New findings help estimate how variations of controllable factors such as pH, salinity and additives affect self‐assembly patterns and aggregate properties. Recent advances in the development of molecular thermodynamic aggregation models, factors restricting implementation of these models and trends in the field are discussed. © 2015 Society of Chemical Industry

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Thermodynamic Model of Petroleum Fluids Containing Polydisperse Asphaltene Aggregates

Cited by 23 publications

References 39 publications

RETRACTED: Striking behavior of the rheology in heavy crude oils by adding nanoparticles

RETRACTED: Striking behavior of the rheology in heavy crude oils by adding nanoparticles

New Techniques and Methods for the Study of Aggregation, Adsorption, and Solubility of Asphaltenes. Impact of These Properties on Colloidal Structure and Flocculation

Molecular thermodynamics of soft self-assembling structures for engineering applications

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