Asphaltene aggregation in organic solvents

Oh, Ki Keun; Ring, Terry A.; Deo, Milind

doi:10.1016/j.jcis.2003.09.054

Cited by 80 publications

(65 citation statements)

References 25 publications

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“…We interpret the onset of precipitation in terms of a phase separation. If we take the concentration of (for example) toluene/heptane mixtures at the onset of precipitation from the figures reported by Oh et al, 79 we can calculate a volume fraction average of their solubility parameters and χ fv using the parameters in Table 1. If we then assume a value for an asphaltene component solubility parameter, the data of Oh et al 79 can be replotted in terms of Δδ.…”

Section: ■ Phase Behavior Of Asphaltene Solutionsmentioning

confidence: 99%

“…If we take the concentration of (for example) toluene/heptane mixtures at the onset of precipitation from the figures reported by Oh et al, 79 we can calculate a volume fraction average of their solubility parameters and χ fv using the parameters in Table 1. If we then assume a value for an asphaltene component solubility parameter, the data of Oh et al 79 can be replotted in terms of Δδ. For example, for asphaltene components with solubility parameters of 21.28 and 21.03 MPa 0.5 , we calculate the plots shown in Figure 8, where we have drawn lines through the data points simply as a guide to the eye.…”

Section: ■ Phase Behavior Of Asphaltene Solutionsmentioning

confidence: 99%

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Asphaltene Aggregation and Solubility

2015

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An attenuated association model describing the aggregation of asphaltenes in solution is extended to derive an equation for the weight-average degree of association and account for phase behavior. The weight-average molecular weight is calculated to be higher than number average, as it must be for a polydisperse material, but not by enough to explain the very large differences in these quantities reported in the literature. Binodals and spinodals are calculated using expressions derived previously, but modified to account for free volume (thermal expansion) differences. The phase behavior of asphaltene solutions is examined in more detail, particularly in the dilute solution regime. It is shown that the formation of nanoaggregates significantly affects the critical value of the χ interaction parameter. The phase diagram is highly asymmetric and the phase boundary approaches the pure solvent composition limit. This has a number of implications in terms of asphaltene solution characterization and the nature of asphaltene solutions. The results indicate that there are toluene insoluble asphaltene components, but these could exist as microphase-separated clusters stabilized against further aggregation by steric and kinetic factors. This would explain the large difference between observed number and weight-average molecular weights. In addition, because of the shape of the binodal curve at low concentrations, experimental data that have previously been interpreted in terms of a critical cluster or micelle concentration are shown to be consistent with a microphase separation.

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Section: ■ Phase Behavior Of Asphaltene Solutionsmentioning

confidence: 99%

Section: ■ Phase Behavior Of Asphaltene Solutionsmentioning

confidence: 99%

Asphaltene Aggregation and Solubility

2015

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“…The dissolution of bitumen in a solvent has a large effect on its structure 4 . Toluene is a solvent able to dissolve the asphaltene fraction.…”

Section: Introductionmentioning

confidence: 99%

“…On order to further detail the structures, atomic force microscopy (AFM) was used for the observation of a heat-cast bitumen film, thus preserving the solid state morphology 10,11 . Masson at al, 2005 modeled asphalt as a multiphase bitumen consisted of a nanostructure called "bee" and dispersed phases on the matrix referred as the catana or catanic phase 4 . On the literature there are a lot of discussion about the composition of the bees.…”

Section: Introductionmentioning

confidence: 99%

Solvent effect on the morphology of the bee: structure observed by atomic force microscopy on bitumen sample

et al. 2014

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The objective of this work was to characterize the asphaltic cement penetration grade 30/45 (CAP 30/45) based on the morphology of nanostructures called "bee" structure observed and its modification when the binder was diluted in heptanes or toluene. The morphology of CAP30/45, toluene and heptane films was studied by Atomic Force Microscopy (AFM) tapping mode and showed typical "bee" structure in asphaltic cement films, but this structure is not visible on the other films. While, toluene completely dissolved the bees, films attacked with heptane still presented some structures left.

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“…Some of reservoirs are water-wet and altered to be oil-wet during oil production [19]. This wetting inconsistency could severely affect the rheological properties of reservoir fluids in porous reservoir rocks and influence the multiphase flow displacement efficiency during the oil exaction in surfactant flooding process [20]- [22]. So, it would be necessary to investigate the wetting and displacement of liquids in both water-wet pore and oil-wet pore.…”

Section: Introductionmentioning

confidence: 99%

Pore Wetting and Its Effect on Breakthrough Pressure in Water-Wet and Oil-Wet Pores

Li¹,

Fan²

2014

IJCEA

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Abstract-Pore wetting plays an important role on enhanced oil recovery because of its effects on fluid saturation, flow behavior and displacement breakthrough pressure of reservoir fluids in porous medium. This paper aims towards measuring contact angles of alcohol aqueous solutions and breakthrough pressures required for air displacing alcohol aqueous solutions in a single micro-size water-wet pore and oil-wet pore. The liquids used are methanol, ethanol, 1-propanol aqueous solutions which could represent the fundamental components of surfactant solutions used in surfactant flooding process. The pores used are silica pores and PMMA pores, which simulate water-wet pores and oil-wet pores in the oil reservoirs. Our results indicate that the contact angle of alcohol aqueous solutions in a silica pore and PMMA pore decreases when the concentration of alcohol increases before reaching CMC. The contact angle decreases more dramatically with the alcohol concentration in an oil-wet pore than in a water-wet pore. The breakthrough pressure increases linearly with the surface tension in the water-wet pore. However, in the oil-wet pore, the breakthrough pressure stops increasing with surface tension when the surface tension is larger than around 35 mN/m. Index Terms-Enhanced oil recovery, displacement, multiphase flow, pore wetting.

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Asphaltene aggregation in organic solvents

Cited by 80 publications

References 25 publications

Asphaltene Aggregation and Solubility

Asphaltene Aggregation and Solubility

Solvent effect on the morphology of the bee: structure observed by atomic force microscopy on bitumen sample

Pore Wetting and Its Effect on Breakthrough Pressure in Water-Wet and Oil-Wet Pores

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