The composition and distribution of saturated hydrocarbons (alkanes, steranes, and terpanes) of oils from the Ulyanovsk oblast of the Volga-Urals oil and gas basin were studied. Wax fractions were isolated from crude oils, and C48-C52 high molecular mass n- alkanes, C35-C52 alkylcyclopentanes, and C24-C42 2 and 3 monomethylalkanes were identified in these fractions. Based on the data on the composition of C10-C36 n-alkanes, C19-C35 terpanes, C21-C30 steranes, and C40+ alkanes, it was shown that the oils in question were generated by marine organic matter in carbonate sediments. Oil from the Novolabitovskoe field (1981-1992 m) substantially differs for the other oils in terpane and sterane compositions. These differences are supposedly due to another source of organic matter.
