Compositional Characteristics and Geochemical Significance of N-alkanes in Process of Crude Oil Cracking

The simulation experiments with crude oil samples have been performed in laboratory by using high temperature simulative techniques, and the characteristics of change of compositions have also been analyzed by gcochemical methods in the cracking process. The results indicate that before a large number of gaseous hydrocarbons being generated by cracking of crude oil, the n-alkanes of high molecular weight from crude oil has already begun to be pyrolyzed, and C+15 hydrocarbon mainly cracked into C6–C14. With increasing maturity, C6–C14 is further transformed into C1–C5, accompanied by the output of benzene, ultimately forming methane and cracking bitumen. In the pyrolysis of n-alkanes process, abundance of benzene and its homologue show significantly increasing, which can be used as potential distinguishing marks of crude oil cracking. Besides, comparative simulation experiments on n-hexadecane have been performed in laboratory by the same experimental condition, and it shows that the characteristics of change of compositions are basically the same as that of n-alkanes in crude oil.