Facies model of the B13 formation of the Nepean vend formation and its use in the formation of the exploration program

The complex geological structure of the oil and gas fields of the Siberian Platform, the facies variability of the Vendian terrigenous deposits, the anisotropy of filtration and reservoir properties cause significant difficulties in allocating sites for exploration and production drilling. In such conditions, it is extremely important to create a detailed facies model based on high-quality initial geological and geophysical information to determine the minimum and sufficient drilling volume.
Goal. To create a detailed seismofacial model of the basal deposits of the Nepean formation.
Methodology and scope of research. To create a detailed facies model, a sedimentological description of the core of 17 wells drilled by Gazpromneft-GEO LLC was carried out. For 46 wells drilled before the 2000s, a detailed description of full-size core samples, reference samples and grinds was carried out. The results of the sedimentological study of the core were combined with GIS data and 3D seismic interpretation.
Results. Based on the results of core studies and 3D seismic interpretation, a detailed facies model of the B13 formation deposits has been created. Unique data on the structure of the basement and weathering crust, which have a significant impact on the structure of the basal deposits of the Nepean formation, have been obtained. The main facies types are identified and characterized. The sequence of the development of the Nepean sedimentary basin has been restored and the geometry of sand bodies has been determined. It has been established that the best collector properties (before salinization) are characterized by facies of removal cones and distribution channels, which are confidently distinguished by the core and with the help of modern 3D seismic exploration.
Conclusion. The results obtained — methods and approaches, conceptual models, dimensions of facies bodies, their connectivity and FES can be used for analogous deposits in the region in order to create a reliable predictive basis for drilling and production forecasting

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