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

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.