Recent data on the geochemistry of Paleozoic oils in the West Siberian Plate are systematized. Based on physicochemical and biomarker characteristics, Paleozoic oils are divided into three families. Family I oils are of marine genesis and are related to Paleozoic rocks. Family III includes typical continental oils derived from Lower-Middle Jurassic source rocks of bog-lake and bog origin. Polygenetic Family II oils are a mixture of oils of genotypes I and III. On the basis of the ratio of trisnorgopanes Ts/Tm, the maturity of Paleozoic oils corresponds to MC12-MC2.
