Effect of Reaction Pathways on the Kinetic Modeling of Aquathermolysis of Heavy Oils

The proposal of a reaction scheme during the kinetic modeling of heavy crude oil upgrading is an important step. Therefore, the study of the effect of using different reaction pathways on the kinetic modeling for the aquathermolysis of Ashalcha heavy crude oil was studied. A total of 10 and 13 pathways for the reactions of SARA (saturates, aromatics, resins, and asphaltenes) and gas fractions were considered in the kinetic modeling. The yield predictions using both schemes showed similar results for asphaltenes, saturates, and gas fractions. For resin and aromatic yields, the more complex network displayed a more accurate fit, reducing the average absolute error value from 4.83% to 3.59%. The different values obtained for the kinetic parameters suggest two different reaction mechanisms: for the 13 reaction pathways, the in-series reactions between asphaltenes, resins, and aromatics, including their corresponding condensation reactions, are promoted, while for the 10 pathways for SARA reactions, the parallel conversion of asphaltenes and resins to light fractions displayed higher rates. Resin molecules exhibited higher reactivity than asphaltenes. The more suitable reaction mechanism is that using 13 pathways in the network, based on the reactions of SARA fractions reported in the literature. Similar rates were noticed for the agglomeration and cracking reactions of aromatics, resins, and asphaltenes.