Abstract
Abstract This paper describes a new anomalous section of the Bazhenov Formation in the Urengoy oil and gas condensate field in the north of West Siberia. Article 1 presents the lithological core description, the division of the main rock into lithotypes, and the results of grain size measurements and of palynological analysis. The study found that gray sandy-clay deposits and sandy vein-like bodies are younger than their host rock in the Bazhenov Formation represented by black kerogen-siliceous-clay. Based on palynological studies and the similarity of the mineral and granulometric compositions of the studied sandstones with the sandstones of the Achimov strata, it was assumed that the studied clastic rock belongs to the Achimov deposits, which were intruded into the deposits of the Bazhenov Formation.