Modeling and simulation of asphaltene precipitation by normal pressure depletion

Asphaltene Precipitation in Paraffinic Froth Treatment: Effects of Solvent and Temperature

“…Asphaltene precipitation and phase equilibrium have been explained by the regular Flory–Huggins model (RF-HM) and EOS, as we briefly overviewed in section . In modeling asphaltene precipitation using the regular solution theory, n -paraffin-diluted oil is typically assumed to be a pseudo-two-component system consisting of asphaltenes as one component and maltenes with n -paraffin solvent as a second component. ,,, Wang and Buckley successfully predicted the onset of asphaltene precipitation through the two-component model using the refractive index to estimate the solubility parameters.…”

“…Stability or precipitation of asphaltenes in heavy oil or bitumen was generally described by two mechanisms (models) in the literature: solubility and colloidal. The first mechanism considers asphaltenes being dissolved in the oil or oil fractions, such as maltenes, and the asphaltene precipitation is the result of phase separation. − This model was most commonly used for predicting asphaltene precipitation using the approaches of regular solution theory and equations of state (EOS). Hirschberg et al were the first to propose the thermodynamic solubility model.…”

“…Asphaltenes were considered as a pure component, and the oil system was considered as either two pseudo-components (asphaltene including resins and solvent) or three pseudo-components (asphaltenes, resins, and solvent), depending upon whether the resins are associated with asphaltenes . The work of Hirschberg et al was later adopted or modified by many other researchers. − The second mechanism considers asphaltenes present in crude oil as colloidal particles (micelles) stabilized by resins. − The critical micelle concentrations are reported in the literature. , On the basis of this mechanism, asphaltene solubility is controlled by partitioning of resins between the colloidal particle surface and the surrounding medium; asphaltene precipitation is considered to result from a loss in the stabilizing function of the resins associated with desorption of resins from the colloid surface as a result of changes in the properties of the medium. − As Wiehe emphasized, resins solubilize asphaltenes by more than just acting as a solvent. The resin–asphaltene interaction is not a specific interaction, such as hydrogen bonding; it is likely an interaction between large, flat polynuclear aromatics through dispersion forces.…”

“…They used the Florry–Huggins theory to calculate the amount of asphaltene precipitated and the Flory–Huggins interaction parameter (χ) from the solubility parameters and molar volume. The Hirschberg et al approach was adopted by other researchers for predicting asphaltene precipitation , and later was modified to address the assumptions made in this model. − , Wang and Buckley also assumed the asphaltene–oil system as a pseudo-binary system and calculated the solubility parameters from refractive index measurements. In their modeling, Yarranton and Masliyah treated asphaltene as a mixture of several fractions having different densities and molar masses .…”

Thermodynamic modelling of asphaltene precipitation and related phenomena

“…The model of Hirschberg and coworkers was later used by other authors [99][100][101], but it is limited to a monodisperse asphaltenic fraction that precipitates as a pure component. Modifications have been suggested to deal with the assumption that the precipitated phase contains not only pure asphaltene but consists of a phase concentrated in asphaltenes containing also a fraction of solvent.…”