Source: Rosneft – An important disclaimer is at the bottom of this article.
Geochemists at Rosneft’s Tomsk Research Institute have published** the results of a 30-year study into ancient oil varieties. The findings are important for reconsidering the history of hydrocarbon formation. This new understanding of oil’s structure will improve the accuracy of oil and gas prospect assessments and the efficiency of deposit development.
This pioneering study, which was unprecedented in terms of its duration and scope, aimed to investigate alkylbenzenes, a key oil component that affects the quality of gasoline. Between 1998 and 2025, specialists from the Tomsk-based institute analysed over 500 types of oil from 11 oil-producing regions in Russia and overseas.
Thanks to technological advances in the study of alkylbenzene composition in oil samples, a machine learning-based approach has been employed for the past two years. The resulting models have accurately determined the origin of the oil and the conditions under which it formed.
High concentrations of tert-butylbenzene, a substance previously considered uncharacteristic of such geological formations, have been detected for the first time in a number of ancient oil varieties in Eastern Siberia (the Kuyumbinskoye and Yurubcheno-Tokhomskoye fields, which are developed by Rosneft enterprises).
The results of the study help to more accurately determine the initial source of the oil’s formation. The presence of tert-butylbenzene indicates that the oil belongs to the Riphean age (ancient varieties). This data is used in basin modelling to predict oil migration and the oil and gas potential of the territory, as well as to inform field development approaches.
* The oil was extracted from rocks ranging in age from 1.1 billion to 5 million years old, from the Meso-Neoproterozoic to the Cenozoic era.
** The article “Composition and distributional patterns of C3- and C4-alkylbenzenes in oils and source rocks from Meso–Neoproterozoic to Cenozoic” authored by Nikolai Oblasov, Ilya Efthora, Ivan Goncharov, and Svetlana Fadeeva has been published in the renowned international journal Organic Geochemistry, which specializes in research on all aspects of organic geochemistry.
Department of Information and Advertising
Rosneft
January 28, 2026
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