--> Abstract: Types of Reservoirs in the Vendian-Cambrian of the Siberian Platform and their Connection with Facies, by V. Kuznetsov; #90990 (1993).

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KUZNETSOV, V., Gubkin State Academy of Oil and Gas, Moscow, Russia

ABSTRACT: Types of Reservoirs in the Vendian-Cambrian of the Siberian Platform and their Connection with Facies

Carbonate and carbonate-evaporite deposits of the Vendian-Cambrian of the Siberian platform are one of the main producing complexes of the region. Over 25 commercial oil and gas pools have been discovered in them. Three types of reservoirs have been distinguished according to the internal structure of the producing interval and ratio of permeable to impermeable layers. In a massive reservoir, practically all the producing interval is composed of permeable rock (Srednebotuobinsk, Bolshetirsk areas). In a multilayer reservoir, the permeable layers are interbedded with slightly permeable ones. One oil-water or gas-water contact is formed, but the commercial reserves are concentrated in the permeable layers (Verkhnevilyutchansk, Vilyisko-Dzherbinsk areas). In a single-layer reservoir, one thin bed occurs in a low permeable section and the productivity of these types of reservoirs has not been tested yet.

The structure and quality of the reservoirs of the two main producing horizons is related to their carbonate facies. The Danilovsky (Ustkutsk) sequence was deposited in a shallow marine environment with a low-relief sea bottom and a progressive increase of salinity from northeast to southwest. Multilayer reservoirs were formed under these conditions.

Reservoir properties deteriorate regionally from northeast to southwest as limestones are replaced by micritized dolomites. The basin during the Osinsk was more differentiated. Two huge shoals existed, corresponding to the Nepsko-Botuobinsk and Baikitsk anteclises separated by relatively deeper water areas. Organic buildups developed on the slopes of the shoals. The multilayer reservoirs developed in the shoal areas; the massive reservoirs are the organic buildups; and the thin single-layer reservoirs formed in the deeper water areas.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.