Radiolytic nature of n-alkene/n-alkane distributions in Russian Precambrian and Palaeozoic oils

Five Russian olefin-containing crude oils from Precambrian and Palaeozoic reservoirs were examined for n-alkene/n-alkane distributions. In each of the oils, the content of n-alkenes Cm (sum of all isomers) was found to be nearly directly proportional to the content of the coexisting n-alkane Cm and to the number of C-atoms in the molecule (m). Also, there are reported n-alkene/n-alkane distributions measured in irradiated oils (which were free of olefins before irradiation). Hypothetical radiolytic n-alkene/n-alkane distributions calculated by the assumption that all C-C n-alkane bonds are equivalent for the dehydrogenation of n-alkane to n-alkenes (as this takes place by radiolysis of n-alkanes) were found to be similar to those observed in both the natural olefin-containing crudes and in irradiated oils.