Methods of detailed correlation of well sections in the study of the geological structure of Upper Jurassic and Lower Cretaceous rock complexes on the example of the Tevlinsko-Russkinskoye oil field of the Surgut arch Part 1. Substantiating the formation features of the Upper Jurassic Bazhenov formation proper and its anomalous sections

UDK: 551.7.02

DOI: 10.24887/0028-2448-2020-8-18-21

Key words: methodological techniques, correlation of well sections, sequential paleoprofeling, Bazhenov formation, its anomalous sections, compensatory Achimov pack, oil-producing formation

Authors: I.S. Gutman (IPNE LLC, RF, Moscow; Sergo Ordzhonikidze Russian State Geological Prospecting University, RF, Moscow), S.V. Arefyev (LUKOIL-Western Siberia LLC, RF, Kogalym), A.I. Mitina (IPNE LLC, RF, Moscow)

We have developed methodological techniques for studying the structure of intervals field on the basis of detailed correlation of well sections: selection of the most informative complex of well-log curves applied to geological conditions at each geological features; an initial allocation of solid intervals of the profile used as main and auxiliary markers, as if the grip is located between the pervious seams and streaks; tension and compression well-log curves; rendering reference intervals, limited to one or two well-log curves; sequential paleoprofeling repeated change of line of settlement, to ascertain the presence of specific changes in the context between the two adjacent lines of the comparison;
The first part explains the nature of formation of the upper Jurassic anomalous sections of the Bazhenov formation as the result of the accumulation of precipitation upon immersion of the individual blocks in considerationem faults with subsequent widespread precipitation accumulation actually Bazhenov formation, after which dip was involved previously stationary adjacent blocks with an offsetting limits on the accumulation of precipitation of the lower Cretaceous Achimov sequence, resulting in rocks of the Bazhenov formation actually are "upturned" over the anomalous sections, whereas the thickness of the Achimov bundle over the Bazhen proper is minimal.
In the second part, well sections of the lower Cretaceous Sortym formation were correlated between two parallel markers: the Georgievskaya formation and the Urievskaya unit; wells were grouped by section types in order to identify the block structure of the studied deposits; and correlation schemes were combined with seismic data.
Based on the developed methodological techniques for studying lower Cretaceous deposits, it is concluded that during their formation, vertical sinking of blocks along consedimentation faults and equal-speed deflection in the same time intervals caused the clinoform occurrence of rocks; the complex of studies allows us to assume the presence of oil-producing formations in the sedimentary column.

1Gutman I.S., Saakyan M.I., Ursegov S.O. et al., Metodicheskie rekomendatsii k korrelyatsii razrezov skvazhin (Methodological recommendations for the correlation of well sections): edited by Gutman I.S., Moscow: Nedra Publ., 2013, 112 p.