Evaluating maturity of source rocks by aromatic compounds: A case from Dongling Block, Songliao Basin

The characteristics of the thermal evolution of aromatic maturity parameters, such as methyl phenanthrene, alkylated dibenzothiophene, dehydroxy-tocopherol and triaromatic-sterane series compounds are discussed on the basis of molecular organic geochemistry and GC-MS analysis of the source rocks in the Dongling area of the Songliao Basin. The distribution characteristics of aromatic hydrocarbon chromatography, the methyl phenanthrene index (MPI), the ratio of β/γ dehydroxy-tocopherol, 4-/1-MDBT, 4,6-/1,4-DMDBT, TASC27 (20R)/C28 (20R), the content of the triaromatic-sterane series and vitrinite reflectance measurements all suggest that the Lower Cretaceous Quantou Formation source rock is in the middle stage of maturity, whereas the Lower Cretaceous Yingcheng Formation and the Upper Jurassic Huoshiling Formation source rocks have reached a high maturity stage.