Structural features of carbonate horizon ОI-II, Srednebotuobinskoe field

UDK: 553.98.061.43

DOI: 10.24887/0028-2448-2021-7-70-73

Key words: osinsky horizon, circle shape anomaly, zone of improved reservoir properties, seismic attributes, Nepa-Botuoba anteclise

Authors: E.S. Sharapova (RN-Exploration LLC, RF, Moscow), R.B. Sultanov (Taas-Yuryakh Neftegazodobycha LLC, RF, Irkutsk), R.S. Urenko (Taas-Yuryakh Neftegazodobycha LLC, RF, Irkutsk), A.V. Gaiduk (RN-Exploration LLC, RF, Moscow), K.A. Neustroev (Rosneft Oil Company, RF, Moscow)

This article is devoted to the structural features of the OI-II formation at the Srednebotuobinsky oil-gas condensate field, which is one of the largest oil fields in Eastern Siberia. The field was discovered 50 years ago. The main target are the ancient Vendian sandstones of the Botuoba horizon. The production started in 2013. The second largest reservoir is the OI-II formation, but this object is still at the stage of exploration. Exploration of the field has been conducted since the 1970s, but no commercial oil inflows have been received from the Osinskian horizon (OI-II formation). The formation has a complex and heterogeneous geological structure, and for a long time there was no understanding which zones are associated with the existing commercial inflows in several wells, as well as how these zones can be predicted for the purposes of production drilling. However, thanks to the integrated approach to the study of deposits used in Rosneft Oil Company, it was possible to identify patterns of distribution of zones of improved reservoir properties, map these zones and test them using horizontal drilling. This project shows how important it is to use all available research tools – borehole data with an extended log complex, 3D seismic data, core data with a detailed sedimentological description. The Scientific Center of Rosneft RN-Exploration LLC proposed wells for re-testing and drilling for the OI-II formation, and the subsidiary company Taas-Yuryakh Neftegazodobycha LLC supported this initiative and carried out work on the field. Based on the results of successful tests a further research program was formed, which was successfully approved by Rosneft. The work methodology developed at the project can be applied to other similar objects in the Eastern Siberia.