Modeling of Asphaltene Deposition Kinetics

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there are several deposition models proposed in literature, however, they lack precision and are mostly based on outdated assumptions that do not correctly capture the physics behind asphaltene deposition reported in the last decade.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.