Geological structure and oil and gas potential of the Triassic deposits in the junction zone of the Vilyui syneclise and the Aldan anteclise

Objective. To clarify the geological structure of the Triassic deposits in the junction zone of the Vilyui syneclise and the Aldan anteclise and to identify promising zones and objects for the studied Triassic deposits in terms of oil and gas potential. Materials and methods. The study used previously published sources, deep well logging data, adjusted stratigraphic breakdowns and the results of testing the intervals of the Triassic deposits in deep wells. The well data were used for a comprehensive analysis of new seismic exploration data obtained during seismic exploration work over the past 10 years. Results. Analysis of core description data and well logging records allowed us to describe the lithological structure of the productive Triassic deposits and assume the sediment formation environments. Adjusted stratigraphic breakdowns were tied to seismic time sections at well points. Reflecting seismic horizons were correlated with stratigraphic boundaries. Structural surfaces and thickness maps of the Triassic complex were constructed based on the seismically traced horizons. Wedging-out zones of the Nedzheli, Tagandzha and Monom formations were outlined. Faults were identified and traced using seismic data. A comprehensive analysis of all well and seismic data, obtained during interpretation, identified promising oil and gas zones and objects near the wedging-out lines. Conclusions. The Nedzheli Formation is distributed over a significantly smaller area than other Triassic formations. The areas of distribution of the Tagandzha and Monom formations coincide. In the pinch-out zone, there is a high probability of sand deposits that can serve as hydrocarbon reservoirs. The wedging-out zone is highly likely to contain sand deposits, which are potential reservoirs that, by decreasing thickness, form lithologically limited traps for hydrocarbons. In the western and northern parts of the study area, the oil and gas potential is associated with anticlinal structures complicated by faults. The contours of promising zones and objects can serve to clarify the direction of further geological and geophysical studies of the territory for oil and gas potential.