Features of the microcomponent composition of pore solutions of rocks of the Bazhenov Formation in Western Siberia

Abstract

The results of experimental studies of the macro- and microcomponent composition of pore solutions of bituminous clay-siliceous rocks of the Bazhenov Formation (BS) of Western Siberia, containing up to 12.63% Corg (“normal rocks”), as well as silt-sandstones from the “anomalous” section are presented. BS with a Corg content of up to 0.63% (“abnormal” rocks) obtained on the basis of a study of aqueous extracts from core samples. It has been established that pore solutions of “normal” BS rocks have a sulfate-bicarbonate-sodium composition, and “abnormal” ones have a hydrocarbonate-sodium chloride composition. In pore solutions of both “normal and“ abnormal ”rocks relative to ocean water, the following were noted: a) concentration of Mn, Co, Ni, Cu, Zn, Mo, Sb, Cd, Ba, V, Cr of various degrees of intensity; b) increased content of Cs, Pb, Ti only in pore solutions of “abnormal” rocks; c) reduced content of Li, B, Rb, Sr. A direct relationship was found between the contents of Li, B, Ba, Sr, U, Mo, Cd, Sb, and Ni with the content in the Corg rock. For V, Cs, Sb, Rb, Ti, Mn in pore waters, the relationship with the amount of Corg in the rocks is close to the inverse relationship. In the pore solutions of “normal” BS rocks, the Ba content is equal to or higher than the Sr content, which is anomalous with respect to the stratal waters of most oil fields and ocean water and, apparently, is associated with the peculiarities of the accumulation of organic clay deposits, since in “anomalous” rocks The BS content of Sr is two times higher than the Ba content, which is closer to the usual for most natural waters.