A Comparative Analysis of Aquathermolysis Kinetics in Heavy Oils: Benchmarking Reaction Pathways across Multiple Systems

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Developing kinetic models is crucial for designing reservoir simulators that predict and optimize production strategies for heavy crude oil under steam injection processes. However, the diversity in heavy crude oil characteristics and the complexity of the chemical reactions involved pose significant challenges to gaining a comprehensive understanding of the reaction system. In this study, a systematic cross-system comparison of aquathermolysis kinetics is conducted using multiple crude oils in the absence and presence of diverse catalysts and hydrogen donor solvents. The goal is to identify consistent behaviors in the changes in the crude oil composition and gas production. Each kinetic model analyzed employs a unified numerical methodology to determine the kinetic behavior of different pseudocompounds, thereby minimizing the influence of varying computational parameters such as the selection of objective function, solving algorithms, and optimization methods.The results show that noncatalytic aquathermolysis systems exhibit the lowest reaction rates across most pathways. In contrast, the highest reaction rates are generally observed for the conversion of asphaltenes to resins and resins to aromatics as well as their respective reverse reactions. Furthermore, benchmarking of the reaction systems enabled the identification of catalytic combinations that offer the most favorable balance among conversion efficiency, selectivity, and minimization of undesirable byproducts in its corresponding reaction system. These findings position this study as a valuable reference for future research on kinetic modeling and catalyst design.