--> ABSTRACT: Depositional Controls on Reservoir Quality within the Lower Cretaceous BS[10] Interval of the Central Western Siberian Basin, by J. M. Rine, R. A. James, and N. Dyeschenya; #91021 (2010)

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Depositional Controls on Reservoir Quality within the Lower Cretaceous BS[10] Interval of the Central Western Siberian Basin 

RINE, JAMES M., ROBERT A JAMES,  and NICOLAI DYESCHENYA

This study presents the findings of a detailed sedimentologic examination of cores from seven oil fields in the heart of the Middle Ob Oil and Gas Region. Objectives of this study were to develop an accurate model for predicting depositional trends within the BS[10] interval and to examine the relationship between reservoir quality and depositional facies. The BS[10] interval consists generally of arkosic, moderate to well sorted, fine- to medium-grained sandstones within a sequence of argillaceous shales. The shale-rich intervals consist of claystones to silty claystones intercalated with laminations to thin beds of siltstones to fine-grained sandstones. Fine-grained particles of carbonaceous material are common throughout the sandstones and shales. Previous studies of the BS[10] interval place it in a general "topset" setting with the prevailing opinion that a majority of the sandstone reservoirs were formed by shallow marine processes. Detailed core examinations during this study, however, reveal that within the central portion of the basin the regional trend is that of fluvial/deltaic facies in the east-southeast grading to shallow marine facies in the northwest. The fluvial/deltaic sandstone sequences consist of channel-fill sands, pointbar deposits, levees, and crevasse splays. Shallow marine sand bodies appear to consist of tidal inlet sand bars and offshore bars. Best reservoir quality sands appear to be within cross-bedded portions of the fluvial/deltaic channel facies. 

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.