Summary
Asphaltene deposition triggers serious flow assurance issues and can significantly restrict the production capacity. Because of the complexity associated with asphaltene deposition that includes several mechanisms acting simultaneously, an accurate prediction of asphaltene blockage along the wellbore requires integration of asphaltene precipitation, aggregation, and deposition. In this work, an integrated simulation approach is proposed to predict the asphaltene deposition profile along the wellbore. The proposed approach is novel because it integrates various deposition patterns of particulate flow (which depends on hydrodynamics) with aggregation processes to investigate how the distribution of asphaltene particle size varies (governed by molecular dynamics) after being precipitated out of the oil phase (controlled by thermodynamics).
To improve the predictability capability of simulations, a direct input from the wellbore flow simulator is used to update the velocity profile after the wellbore radius changes beyond a certain predefined threshold. The fraction of asphaltene precipitation is determined using the asphaltene solubility model and combined with aggregation models to feed into deposition calculations.
Wellbore blockage was examined for two cases with and without the aggregation mechanism included. A sensitivity analysis was carried out to study parameters that affect the severity of blockage, such as range of pressure-temperature along the wellbore, flow velocity, and radial distribution of asphaltene particles. The simulation approach proposed in this paper provides an in-depth understanding of the wellbore flow assurance issues caused by asphaltene deposition and thus provides useful insights for improving the predictions of production performance.
Asphaltene Precipitation Modeling of Sadi Formation in Halfaya Iraqi Oil Field