An Experimental and Simulation Study of Asphaltene-Induced Permeability Impairment under Natural Depletion Condition

摘要

Asphaltene deposition is one serious problem in many of Iranian oil reservoirs. So, a deeper understanding of this phenomenon is essential to prevent its related formation damage and increasing ultimate production through selecting a proper planning. The major goals of this study are (a) investigation of asphaltene deposition on rock surfaces under natural depletion condition during dynamic flow tests, and (b) simulation study of asphaltene-induced permeability damage by using commercial software and evaluation of its strengths and weaknesses. To extend the results of this work, asphaltene deposition and simulation study performed on both carbonate and sandstone rocks. The results of dynamic flow experiments show asphaltene deposition is a continuous process causing permeability impairment and is also partially reversible. Simulation results indicate good matching of the experimental data at final steps of the experiments and it means that software should be modified respect to modeling of asphaltene deposition. In addition, surface deposition and entrainment mechanisms are more important in carbonate rocks than sandstones while pore plugging mechanisms depends on the pore size distribution of the rock and it may play same role in carbonate and sandstone rocks. The simulation model considers constant values for adsorption and plugging coefficient, while these coefficients are changing during experiment. All the tests are performed and simulated in accordance to reservoir condition and oil production rate of wells.