Heat flow, thermal history of the source Lower Jurassic Togur suite and hydrocarbon presence in the Bakchar mezodepression (South-East of West Siberia)

• Date: 2020
• Main Authors: Lobova, G.A., Merenkova, A.S., Kuz’menkov, S.G.
• Format: Article
• Language: Russian
• Published: S. Subbotin Institute of Geophysics of the NAS of Ukraine 2020
• Subjects: source suite; reservoir of the hard-to-recover oil; paleotemperature modeling; oil generation density; potentially productive zones; Bakchar mezodepression
• Online Access: https://journals.uran.ua/geofizicheskiy/article/view/201739
• Journal Title: Geofizicheskiy Zhurnal

The poorly studied Bakchar mezodepression which is similar in geological structure to the industrially oil-and-gas bearing Nyurol and Ust-Tym megadepressions of the south-east of Western Siberia is a potentially productive object for conducting predictive exploratory studies on the Lower Jurassic and pre-Jurassic reservoirs of hard-to-recover oil. The purpose of the research is to identify and map the catagenetic generation sources of oil generation in the Lower Jurassic Togur oil source suite, to evaluate the generation density, to predict the oil-and-gas potential of the Lower Jurassic and pre-Jurassic deposits. Paleotemperature modeling was carried out in cross sections of 30 deep wells. The modeling is based on solving the heat conduction equation of a horizontally layered solid with a moving upper boundary, using the original «TeploDialog» computer technology. A schematic map of the deep heat flow density was constructed for the Bakchar mezodepression and framing structures, and catagenetic generation sources of the Togur oil were mapped. The appearance of generation sources is correlated with Alb-Cenomanian, the maximum paleotemperatures were reached 24 million years ago, when the generation sources cover almost the entire distribution area of the Togur suite. The generation sources of Togur oil «work» during almost 92 million years until now. Express-evaluation of the oil generation density identified potentially productive zones for deposits searching in the Lower Jurassic and pre-Jurassic sections. It is a local zone on the Parabel mega nose and a wide strip encompassing the central and northwestern zones of the Bakchar mezodepression.