A New Method to Simulate and Evaluate Asphaltene Plugging Risk in Oil Wells

Summary Asphaltene is normally present in crude oils. Usually, it is dissolved in the bulk oil phase. However, due to the changes in pressure and temperature, asphaltenes may precipitate in the wellbore during production. It would cause well plugging under certain conditions, which is a severe and common problem for many oil production wells. Asphaltene plugging could lead to the decrease of the well productivity and it requires extra well treatment costs for the removal of the deposits. To prevent asphaltene plugging, it is important to investigate its mechanisms and develop a method to evaluate the asphaltene plugging risk for production wells. A new method is developed in this paper to characterize the phase behavior and to simulate the migration dynamics of asphaltenes in oil wells. Accordingly, a graded asphaltene plugging risk evaluation system is also established, and a case study of a deep oil well in northwest China is performed to validate this method. The simulation results demonstrate a good agreement with the field data. Several prevention and control suggestions are proposed based on field experiences and the analysis of the asphaltene plugging behavior.