Prediction of the Phase Behavior of Asphaltene Micelle / Aromatic Hydrocarbon Systems

Pacheco-Sánchez, J. H.; Mansoori, G. Ali

doi:10.1080/10916469808949789

Cited by 35 publications

(16 citation statements)

References 10 publications

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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: 98%

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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Section: Introductionmentioning

confidence: 98%

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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“…To explain the mechanism of precipitation, several models has been proposed, some of them based on liquid-liquid or solid-liquid equilibria (4,5). A good deal of research follows the idea of the self-aggregation of asphaltenes in oil, in which micelles are stabilized by the adsorption of polar compounds (resins) on the interface (6)(7)(8). These micelles form coacervates that can precipitate (4).…”

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confidence: 99%

Properties of Venezuelan Asphaltenes in the Bulk and Dispersed State

2006

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High oil prices have renewed the interest not only in new sources of energy but also in using more efficiently the available oil reserves, which are mostly of the heavy or bituminous type. Many of the problems associated with processing of heavy crude oils come from asphaltenes, roughly defined as fractions which are soluble in aromatic solvents such as toluene and benzene and insoluble in alkanes such as pentane or heptane (1,2). This scientifically vague definition makes difficult a precise characterization of asphaltenes, which composition and structure depends on the source and it is therefore a matter of discussion. In general, the chemical structure consists of an aromatic nucleus with several benzenic rings surrounded by alkyl chains and heteroatoms (1) .However, it is difficult to estimate a precise molecular weight due to association among molecules (3). The behavior of asphaltenes in solution has also 563 JOS

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“…The reported molecular weight of asphaltene varies considerably depending upon the method and conditions of measurement. [6][7][8][9] Pipeline Plugging Due to Wax Deposition Several factors are responsible for the wax deposition in pipelines, including crude oil composition, temperature, flow rate, thermal history, and pressure. Moreover, the amount of deposited wax is affected by the concentration of paraffins, light ends, and nucleating or inhibiting materials in the crude oil.…”

Section: Asphaltenes and Resinsmentioning

confidence: 99%

Investigation of the Effect of Insulation on Wax Deposition in an Iranian Crude Oil Pipeline with OLGA Simulator

Seyfaee

Lashkarbolooki

Esmaeilzadeh

et al. 2012

Journal of Dispersion Science and Technology

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Transportation of waxy crude oil in a cold environment can result in wax depositions, which are solid deposits, on the pipe wall. The formation of paraffin in the bulk of the petroleum is a crystallization process. Deposition in Bangestan crude oil pipelines can cause reduction in flow area and thus decrease in the crude oil feed of Ahvaz-3 production unit. Several techniques have been used to minimize the wax deposition in crude oil flowed through the pipelines, howeverthermal insulation of pipelines is considered as an efficient method. The main objective of this study was to determine the influence of insulation thickness on wax deposition for Bangestan crude oil pipeline of Ahvaz-3 production unit with the OLGA simulator. The results of simulation show that the maximum reduction in wax deposition was obtained by using 3.4 inch of insulation polypropylene.

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Prediction of the Phase Behavior of Asphaltene Micelle / Aromatic Hydrocarbon Systems

Cited by 35 publications

References 10 publications

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

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

Properties of Venezuelan Asphaltenes in the Bulk and Dispersed State

Investigation of the Effect of Insulation on Wax Deposition in an Iranian Crude Oil Pipeline with OLGA Simulator

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