An integrated chemical analysis study of organic carbon, chloroform bituminous extracts, and hydrocarbon biomarkers (n-alkanes, isoprenanes, steranes, terpanes, etc.), as well as the Rock Eval pyrolysis of rocks sampled in exploration areas and fields in the northeast of Tatarstan, has been conducted. It was shown that the main source strata of northeast Tatarstan is the Semilukian (Domanikian) formation, in which the composition of hydrocarbon biomarkers of disseminated organic matter is identical in geochemical parameters to that of oils of the region. The composition of hydrocarbon biomarkers of epigenetic bituminous extracts found in Proterozoic carbonate rocks and crystalline-basement granites air quite different from the hydrocarbon composition of Devonian and Carboniferous oils of the region. There are no geochemical signatures of migration of petroleum hydrocarbons from the basement to Paleozoic sedimentary rocks.