Lithological characteristics of the Kolgan formation of the south-western part of the East Orenburg arch uplift

Based on the study of core material, the lithological features of the deposits of the Kolgan formation of the Frasnian stage in the southwestern part of the East Orenburg arch uplift are considered. This formation is an important oil and gas play. Since picking, almost nonintermittent prospecting and exploration works have been carried out. A large bulk of heterogeneous material is received and processed, which complement and expand the knowledge of the geological structure and genesis of sediments. The research was carried out by petrographic and lithological methods. As a result, 5 lithotypes were identified according to the ratio of carbonate and terrigenous components and structural and textural features. It was found that the carbonate component prevailed in all the selected lithotypes, which distinguished this formation from other similar sections, where terrigenous rocks predominated. The presence of bioturbation of varying degrees of intensity and the presence of tempestites is characteristic.