2009 Volume 52 Issue 6 Pages 322-331
Asphaltene precipitation and deposition is one of the main problems in some of the oil fields. The deposited asphaltene results in partial or total blockage of the wellstring and reducing or completely seizing oil production. Asphaltene deposition problems have been experienced in the field for a long time. Although, the asphaltene precipitation has been studied thoroughly and different parameters that effects this process has been investigated but little work has been carried out in the asphaltene deposition across the production system of flowing oil well. This paper introduces a new comprehensive model for description of asphaltene deposition behavior in wellstring. The mechanisms of asphaltene deposition have been investigated experimentally using an accurate thermal approach. A series of experiments were conducted to observe the role of various parameters such as oil flow rate, temperature and concentration of asphaltene precipitant on the rate of asphaltene deposition. The model of asphaltene deposition was developed based on the results of experiments. There was good agreement between measured and predicted asphaltene deposition rate. Following this, the developed model was applied to an Iranian oil producer reservoir with severe problem with asphaltene deposition. The wellstring model couples the thermodynamic asphaltene precipitation with the developed model of asphaltene deposition. The model was able to predict the asphaltene plugging time properly, and determining the depth and the thickness of asphaltene deposition with respects to the production time. This paper offers readers with the first asphaltene deposition wellstring that uses thermodynamic of asphaltene precipitation and couples it with comprehensive deposition model.
