Sub- and supercritical water in the processes of conversion of Domanik rock organic matter

¹ Institute of Geology and Oil and Gas Technologies, Kazan Federal University, Kazan, Russia
² Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Science, Kazan, Russia

Abstract

Studies on the conversion of organic matter of high-carbon Domanik (siliceous-clay carbonate) rock of the Romashkinskoye deposit with a mineral content C_org of 7.07% in sub- and supercritical water have been carried out. It was shown that subcritical water at a temperature of 320°С and 17.0 MPa leads to a partial decomposition of the kerogenic structure, increasing the yield of bitumen from 3.12 to 3.98%, and a more complete recovery of asphaltenes and heavy C₂₂-C₃₀ n-alkanes from the rock sample. Supercritical water at temperatures of 374 and 420°C and pressures above 24.4 MPa leads to intensive formation of hydrocarbon and inorganic gases in the processes of kerogen decomposition, destruction of aliphatic substituents from condensed heteroatomic structures of resins and asphaltenes, and the carbonate component of Domanik rock. Degradation of the organic matter of the Domanik rock is also accompanied by the formation of saturated hydrocarbons with an increased content of light C₁₂-C₂₁ n-alkanes, and carbonaceous substances, such as carbene-carboids. Changes in the structure of asphaltenes and their paramagnetic properties were determined by the EPR method. The influence of sub- and supercritical water on phase changes in the composition of rock minerals, as well as on the yield and composition of formed gases, was revealed.