Lower-Middle cambrian deposits of Bakhtinsky mega-uplift and neighbouring areas: geological models and prediction of oil and gas accumulation zones

The issue of commercial oil and gas content in the Lower-Middle Cambrian deposits of the Bakhtinsky mega-uplift and neighbouring areas still remains urgent. In 1980s, commercial inflows of oil and gas condensate were obtained here from Usolsky, Charsky, Namansky, and Zeledeevsky horizons on a number of sites, where stratigraphic and prospecting drilling was carried out during the course of geological exploration for oil and gas Since then, there has been no prospecting in the area for 30 years. Because uncertainty in understanding the geological structure, there is still no adequate assessment of hydrocarbon potential of individual traps containing oil and gas accumulations in the Cambrian sediments, or in the area as a whole. Basing on integrated modelling of geological structure of the Lower-Middle Cambrian deposits in the Bakhtinsky mega-uplift and neighbouring areas of the Kureisky syneclise and Baykitsky anteclise, the authors discuss structural and tectonic zoning of the territory looking at the Middle Cambrian Usolsky Horizon Top and Letninsky Formation Bottom, analyse salt content in certain stratigraphic units, as well as spatial position of the Belsky sill relative to the Usolsky Horizon Top. A structural model and dating the pre-Later Vendian Basement uplifts in the territory under consideration is also presented. The results of the obtained data consolidation allowed identifying the predicted zones of accumulation in Cambrian deposits, where further geological and geophysical multidiscipline studies are required to carry out a reliable quantitative evaluation of resource potential