Temperature influence on the composition of high-carbonic Domanic rocks organic matter during hydrothermal treatment in CO<inf>2</inf> atmosphere

Abstract

© Published under licence by IOP Publishing Ltd. Depositions of the Domanic type in the territory of Tatarstan are stratigraphically associated with carbonate-siliceous deposits of the Upper Devonian part of the section. These deposits, enriched with organic matter, are characterized by the ability to generate liquid and gaseous hydrocarbons and accumulate them in the form of deposits of unconventional type. In this paper, the results of geochemical studies of rock samples from the depth interval 1705-1728 m of the Semi-Bug-Buregian deposits of the Berezovskaya area of the Romashkino oil field are presented. It is shown that the rocks, in spite of the narrow core sampling interval, differ in the content of quartz and calcite, as well as in the admixture of minerals such as muscovite, pyrite and albite. The content of organic matter according to thermal analysis data varies from 1.97 to 35.48 %, a significant part of which falls on an insoluble organic matter-kerogen. The influence of hydrothermal processes on the production capacity of the organic matter of these rocks is shown to generate hydrocarbons at temperatures of 200, 250, 300 and 350°C in a carbon dioxide medium. The yield and quality of the products obtained is estimated. The results of the research give grounds to believe that: Firstly, the rocks of the Berezovskaya area of the Romashkino oil field have not fully realized their oil potential and the hydrothermal effect on them contributes to the thermal maturation of organic matter in the rock; second, at these temperatures, more intensive recovery of free hydrocarbons from the rock occurs. Thus, the hydrocarbon potential of the house rock is determined by the composition and content of liquid bituminous components that are in a free state in the rock, as well as the products of destruction of tar-asphaltene substances and macromolecules of insoluble kerogen and, consequently, it can be successfully realized with further optimization of hydrothermal processes directed to increase the quantity and improve the quality of the extracted fluids.