Molecular mass distributions of components of 24 isobaric homologous series of aromatic hydrocarbons were established in crude oils from Lower Cretaceous (Zuunbayan oil field) and Jurassic (Tamsagbulag oil field) deposits. The concentrations of individual C-10-C-14 biarenes and C-14-C-17 triarenes in these oils were determined, the salient features of the isomer composition of these hydrocarbons were revealed, and this composition was correlated with the thermodynamic stability of the compounds
