Geochemistry of Oils from the Northern Timan-Pechora Basin, Russia

A. G. Requejo, R. Sassen, M. C. Kennicutt II, I. Kvedchuk, T. Mcdonald, G. Denoux, J. M. Brooks

Thirty-six oils from the northern Timan-Pechora Basin were geochemically characterized to establish oil-oil correlation and to assess source rock types. The results indicate four oil types. Two types of sulfur-rich oils (range 1.4% to 2.5% sulfur) are identified by gross and molecular properties. These oils are found in the Toravey, South Toravey, and Roman Trebs fields. They are also present in the offshore Prirazlom field, extending the geographic range of sulfur-rich oils into the Pechora Sea. Another oil type exhibits distinctive odd predominance of n-alkanes in the range n-C₁₁ through n-C₁₉ and diminished n-alkanes greater than C₁₉. These oils, which occur primarily in the a. Titov and Labogan fields, show striking similarities to Ord vician-sourced oils from other Paleozoic basins worldwide. Their biomarker and isotopic compositions bear a strong resemblance to oils generated from the Ordovician Viola Limestone of the Anadarko Basin. The fourth oil type occurs in the northwestern potion of the basin in the Khylchuyu field. Some mixing between oil types is evident. The Upper Devonian Domanik Formation is generally thought to be the major oil source in the Timan-Pechora Basin. However, geochemical characteristics of Timan-Pechora oils analyzed are not similar to those of other Upper Devonian sourced-oils, such as those generated from the Duvernay Formation of Western Canada. This may indicate that the Upper Devonian is not an important hydrocarbon source in the northern Timan-Pechora Basin. The Timan-Pechora oils analy ed are generated from Paleozoic carbonate or calcareous shale source rocks, at least one of which appears to be of Ordovician age.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995