PETROGRAPHY AND RESERVOIR PROPERTIES OF SILTY AND SANDY ROCKS OF HORIZON YU1 (CALLOVIAN-OXFORDIAN) IN THE SOUTHEAST OF WESTERN SIBERIA

O. V. Burleva, L. G. Vakulenko, O. V. Dultseva, P. A. Yan

Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russia

The authors have done a detailed petrographic and petrophysical research on silty and sandy rocks of the Callovian-Oxfordian horizon Yu1 in the southeast of Western Siberia. They summarised the results of previous lithological studies within the territory of the Vasyuganskaya Formation and its transition into the Naunakskaya Formation and established regularities of vertical and lateral changes in the silty and sandy rock composition. To the southeast, the quartz content decreases and the content of feldspars and rock fragments increases in the composition of fractured rocks, which indicates the decrease in maturity in this direction. A direct correlation was established between mineralogical and structural rock maturity: the rounding and sorting of fractured rocks usually rise with an increasing quartz part. The authors analysed the relationship between the reservoir properties and petrographic composition of the studied rocks, sedimentation and post-sedimentation factors favouring the formation of reservoir rocks with better reservoir properties were identified. Thus, for several fields at the Kaymysovskiy dome, the post-sedimentation processes without regional extension have a decisive impact on the formation of reservoirs.

Key words: lithology, petrology, reservoirs, horizon YU1, Upper Jurassic, Western Siberia.

DOI 10.20403/2078-0575-2017-1-30-42

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