Cavity structure in oil-saturated Bazhenov and Abalak shale rock in the Western Siberian basin

Abstract

The cavity structure in oil-saturated Bazhenov and Abalak shale rock is analyzed. The Bazhenov reservoirs are of pore and pore–microcavern type. Their cavity structure is formed as a result of the transformation of the mineral component (biogenic silica) and organic component (kerogen) in the rock. The ratio of pore types depends on the mineral composition of the reservoir rock and its degree of catagenesis. Pyrite is the main mineral filling the pore volume and impairing the filtrational properties. The reservoirs of the lower Bazhenov formation are confined to the Correlation Layer and are of fracture-cavern type.