Saturated hydrocarbons of Ulyanovsk oblast crude oils and waxes isolated from these oils

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 C 48 -C 52 high-molecular-mass n -alkanes, C 35 -C 52 alkylcyclopentanes, and C 24 -C 42 2- and 3-monomethylalkanes were identified in these fractions. Based on the data on the composition of C 10 -C 36 n -alkanes, C 19 -C 35 terpanes, C 21 -C 30 steranes, and C 40+ 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.