Modeling of Asphaltene Deposition Kinetics

Abstract

Any change in the crude oil system equilibrium causes asphaltene precipitation, aggregation, and finally deposition on rock or pipe surfaces. Treatment cost and production lost time associated with deposition have a huge impact on production revenue. Therefore, developing a model that can reliably predict the asphaltene deposition behavior is essential. Although there are several deposition models proposed in literature, however, they lack precision and are mostly based on outdated assumptions that do not correctly capture the physics behind asphaltene deposition reported in the last decade. In addition, available models excessively rely on tuning parameters that are purely mathematical parameters with no experimental background or known dependency on influential parameters. It gives their model unnecessary flexibility and can mostly be used to regenerate the deposition processes in which field data are present. The current study attempts to develop a model based on recent research findings that can resolve the shortcomings of the previous models. The developed model treats asphaltenes as a polydisperse system and tracks their behavior (precipitation, advection, diffusion, aggregation, breakage, and deposition) along the flow path. It can successfully simulate the experimental capillary deposition tests and is able to predict particle size distribution, which denotes capturing aggregates behavior at the microscopic level. It explains that the temperature increment, mainly by increasing interaction frequency of aggregates with the deposit surface, can accelerate the deposition process. On the other hand, the composition change depending on how it affects medium stability and viscosity can either enhance or decelerate the deposition process.

Asphaltene Precipitation and the Influence of Dispersants and Inhibitors on Morphology Probed by AFM

“…Considering the three regions previously described, Table 3 shows the calculated aggregation time (t 1 ), that is, the time at which the normalized height starts to drop due to sufficient asphaltene aggregation (the %∆BS signal is dominant); the sedimentation time (t 2 ), that is, the time at which the normalized height remains unchanged; the normalized final height of precipitated material (h d ) and the viscosity of all the n-alkane solutions. In line with other studies [69][70][71], the calculated aggregation time (t 1 ) of Table 3 is consistent with a diffusion-limited cluster aggregation (DLCA) model which corroborates that the viscosity of the solution and attractive forces are responsible for the initial stages of these processes. Figure 2 shows the evolution of the %∆BS signal as a function of the height of the sample until t 1 is reached for each n-alkane.…”

Impact of Asphaltene Precipitation and Deposition on Wettability and Permeability

“…Permeability restoration has been attempted both at the laboratory and field scales by the use of dispersants, 21 chelating agent nanoparticles, laser technology, microwave, and ultraviolet light (UV). The use of laser technology for permeability impairment restoration due to asphaltene has highlighted the degree of permeability restoration dependent on the laser intensity, with the optimum exposure time of 1 h enough to recover the permeability.…”

Modelling the effect of the inhibitors on asphaltene precipitation using Flory–Huggins theory

“…For the first time, Hirschberg attempted to implement the Flory–Huggins theory to predict the precipitation behavior of asphaltene. In 1948, Hirschberg et al proposed a thermodynamic model to describe the behavior of asphaltene in crude oil under the influence of temperature change, pressure, or component composition 11 , 12 . In their model, they used Flory–Huggins theory along with the Soave equation.…”