Asphaltene Deposition during CO2 Injection at Different Pressures; Experimental and Modeling Study

Carbon dioxide miscible flooding has become a popular method for Enhanced Oil Recovery (EOR) because of its high sweep efficiency and contributing to thereduction of greenhouse gas emissions. Moreover, it can significantly favor the asphaltene deposition, which leads to wettability alteration and formation damage. Anovel experimental setup is designed to utilize high-pressure visual cell to study asphaltene deposition on the model rock at reservoir condition. Fluid samples fromone giant Iranian oil fields namely, Kuh-e-Mond, were used at different pressures, and CO2 volume fractions. The process of asphaltene precipitation during pressuredepletion and CO2 injection was modeled using thermodynamic solid model. Tocharacterize the asphaltene, PVT properties of live fluid samples were used. The results of CO2 gas injection show that both the amount and rate of asphaltenedeposition increase as the CO2 mole fraction increases. Increasing CO2 injection from 5% to 20% mole resulted in 40% more in asphaltene deposition at 140 bar and90ºC condition. The experimental data was modelled using PR (Peng-Robinson) equation of state as the best equation to attain the good agreement betweenexperimental and modeling data. The molar volume and interaction coefficients between CO2 and different components of synthetic oil have found as the best parameters to match the experimental and modelling data in solid model. As a resultof this study, an excellent agreement achieved between experimental data and tuned model.