Comparison of Traditional and Sequential Approaches for Estimation of Kinetic Parameters of Heavy Oil Upgrading

Abstract

During the kinetic modeling of reactions with complex feeds, the proposal of reaction schemes is a crucial step, especially when the number of pathways considered is high, since it influences the estimation of kinetic parameters. In this work, the complexity of the reaction scheme and the methodology followed for the estimation of parameters of the kinetic models for heavy oil upgrading were studied. Experimental data reported in the literature for the aquathermolysis of Xinjiang heavy oil were employed. The obtained kinetic parameters exhibited predictions that were more accurate than those reported in the original work. The number of pathways considered in the reaction scheme and the obtained kinetic parameters do not significantly affect the accuracy of the model, but different main reaction routes of SARA and gas fractions were derived. The most appropriate reaction scheme was that obtained with more pathways and a sequential parameter estimation approach. The results showed that the main reactions are in series (asphaltenes ↔ resins ↔ aromatics), and asphaltenes are the main generator for all gas compounds. Being resins the fraction with higher conversion (25.41%) even higher than asphaltenes (14.15%), CO2 and H2 exhibited the highest production among all gases. The methodology employed for the estimation of parameters considerably influences the accuracy of the kinetic model. The sequential approach exhibited lower average absolute error values than the traditional method for all of the lumps, especially for resins and aromatics.