Geological structure of Tomsk oil and gas promising zone: new data

The paper presents the main working results under the Public Contract No. 58. Geological structure of pre-Jurassic Basement and sedimentary cover is updated for the eastern part of the Tomsk Region on the basis of the following information: integrated interpretation of CMP Reflection survey data (24.7 thousand km including 8.5 thousand km processes using the modern software systems); results of drilling 125 deep wells together with 275 wells from the neighbouring areas to update bedding and geopetroleum parameters of the section; and gravimetry and magnetometry data. The authors reconstructed the tectonic evolution of sedimentary cover, which allowed considerable clarifying configuration of I-st, II-nd, and III-rd order structures, identifying a II-nd order negative structure within the Barabinsky-Pikchtovsky monocline, and determining the blocked structure of the territory with fundamentally differing history of tectonic processes. The Beloyarsky Fault divided the area into two blocks until the mid-Middle Jurassic. The north-eastern block was subject to intensive and sustained downwarping while ascending movements; the marginal south-western part of the territory (Bakcharsky depression) experiencing the intensive subsidence was an exception. In the Late Jurassic, the structure-shaping role of the Beloyarsky fault came down sharply. Orientation of tectonic movements and, respectively, paleostructure strikes changed from south-western to north-eastern. In Early Cretaceous time, there was a sharp growth of structures in the south-east accompanied by formation of a single monocline uniting the Chulymsky megaterrace with the Tegul’detsky depression, Barabinsky-Pikchtovsky monocline and the Beloyarsky mega-swell, which resulted in formation of fundamentally different structural blocks, namely: intensively growing south-eastern and subsiding north-western. The results of hydrocarbon generation, migration, and accumulation modelling are comparable to the history of tectonic evolution of the territory. Assessment of Дл Category resource potential of identified exploration targets shows that structures and individual areas inherited from the Late Palaeogene as uplifts are the most promising. As a result, the need to complete regional studies on the periphery of the West Siberian plate is highlighted