ON SOME FORMATION REGULARITIES OF FINAL-SEDIMENTOLOGICAL STAGES IN LOWER CRETACEOUS DEPOSITS (RYABCHIK) OF WESTERN SIBERIA

V. P. Alekseev, E. O. Amon, R. A. Valeev, S. A. Lats, O. S. Chernova, E. A. Schergina

Intensive oil-and-gas production process improvement determines involvement of hydrocarbon fields difficult to recover into this activity. Such accumulations are often composed of rocks with specific appearance named ryabchik [hazel grouse]. Besides traditional bedding in the lower Alymskaya Formation of the Samotlorskoye field, these rocks spread both laterally (A1 reservoir of the Shirotnoye Priobye [Latitudinal Ob]) and through the section (VK1 reservoir of the Krasnoleninsk petroleum region). The article describes their [rocks] facial composition (material constitution, facial features, reservoir properties), the characteristic of stratum structure is given and formation model is proposed. The formation mechanism for ryabchik horizons is determined. This mechanism defines them as final or final-sedimentological stages in the development of the West Siberian sedimentary basin. The widespread development of such equifinal processes that inherent also to VK1 and Yu2 0 reservoirs is suggested.

Key words: Western Siberia, uncomplicated Neocomian subcomplex, ryabchik [hazel grouse], lithologicalfacial analysis, petroleum potential.

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