Influence of Asphaltenes on the Direction of Thermal Transformations of Heavy Oil Hydrocarbons

Thermal transformations of asphaltenes and oils isolated from heavy petroleum of the Usa oilfielb (Timan–Pechora oil-and-gas basin) have been studied, as well as their interplay during thermal treatment. The thermolysis has been performed in a close batch reactor in an argon atmosphere for 2 h at 450°C. Data on the material balance of the process and the composition of gaseous and liquid thermolysis products have been obtained. The structural-group characteristics of the asphaltenes and resins formed by the thermolysis have been studied, and changes in the hydrocarbon composition of the thermolysis products have been analyzed. It has been shown that in the presence of asphaltenes, the direction of the thermal conversion of hydrocarbons is changed. The occurrence of degradation reactions is evidenced by the composition of the gaseous products and the presence of hydrocarbons with a lower molecular weight. Combination and addition reactions of hydrocarbon radicals generated during the thermolysis lead to the formation of resins and asphaltenes, which are further condensed to solid products.