Eulerian Model To Predict Asphaltene Deposition Process in Turbulent Oil Transport Pipelines

Abstract

In this paper, the Eulerian approach was applied to model asphaltene deposition process in turbulent production pipeline. In addition to common mechanisms such as drag, lift, gravity, and molecular diffusion, the most effective deposition mechanisms such as eddy diffusion, turbophoresis, and thermophoresis were considered over a wide range of asphaltene particle sizes (i.e., 1 nm–100 μm). Modeling results showed that, for small submicrometer-sized particles (<1 μm), the diffusion mechanism (including molecular and eddy diffusions) plays a significant role; however, for large particles, because of the inertia effect, eddy diffusion and turbophoresis were the dominant mechanisms. It was also found that temperature gradient has no significant effect on asphaltene particle deposition. In the modeling, the effect of oil velocity, surface roughness, particle size, and surface temperature on asphaltene deposition was also investigated. The results showed that asphaltene deposition velocity was increased with increasing oil flow velocity, while increasing the deposition velocity by increasing the surface roughness occurred only for particles <20 μm in size. Finally, by using the asphaltene particle size distribution based on the log-normal distribution function, the asphaltene deposition flux was calculated and validated with available experimental data.

Deposition of Asphaltene from Destabilized Dispersions in Heptane–Toluene

“…In deposition models the main factors governing deposition rate are the number of destabilized particles, the size of destabilized particles (which governs their diffusivity and transport through the liquid), the flow conditions (hydrodynamics) and other environmental conditions (e.g. temperature) [57,58,59]. Generally, deposition (which involves asphaltene-asphaltene interaction) is not considered to be reaction-limited, even though there is evidence that in the early stages of aggregation and at low heptane vol % the rate of aggregation is reaction-limited [41,42].…”

“…It has been suggested that the rate of deposition of submicrometer aggregates is mass-transport limited, depending on the diffusivity and thus the size of depositing particles. , In deposition models, the main factors governing deposition rate are the number of destabilized particles, the size of destabilized particles (which governs their diffusivity and transport through the liquid), the flow conditions (hydrodynamics), and other environmental conditions (e.g., temperature). − Generally, deposition (which involves asphaltene–asphaltene interaction) is not considered to be reaction-limited, even though there is evidence that in the early stages of aggregation and at low heptane vol % the rate of aggregation is reaction-limited. , In our study, we observe that deposition rate tends to decrease with increasing particle size; see depositions from 70 vol % heptane at increasing destabilization times (Figure a). A decrease in deposition rate with increasing destabilization time from 12 to 20 s may suggest the formation of larger (yet still submicrometer) aggregates with lower diffusivity.…”

Mechanism of an asphaltene inhibitor in different depositing environments: Influence of colloid stability

“…surface coatings. Coatings can alter the chemistry and morphology of the surface, thus altering both the propensity for adsorption and the nature of the fluid flow across the surface (Dudášová et al, 2008b(Dudášová et al, , 2008aLin et al, 2016;Pradilla et al, 2016;Seyyedbagheri and Mirzayi, 2017;Sung et al, 2016). Coatings of organosilane selfassembled monolayers (SAMs) reduced asphaltene adsorption onto silicon substrates (Turgman-Cohen et al, 2009a, 2009b.…”