Heavy oil hydrocarbons and kerogen destruction of carbonate-siliceous domanic shale rock in suband supercritical water

Abstract

© 2020 by the authors. This paper discusses the results of the influences of subcritical (T = 320 °C; P = 17 MPa) and supercritical water (T = 374 °C; P = 24.6 MPa) on the yield and composition of oil hydrocarbons generated from carbonaceous-siliceous Domanic shale rocks with total organic content (Corg) of 7.07%. It was revealed that the treatment of the given shale rock in sub-and supercritical water environments resulted in the decrease of oil content due to the intensive gas formation. The content of light hydrocarbon fractions (saturated and aromatic hydrocarbons) increased at 320 °C from 33.98 to 39.63%, while at 374 °C to 48.24%. Moreover, the content of resins decreased by almost twice. Insoluble coke-like compounds such as carbene-carboids were formed due to decomposition of kerogen after supercritical water treatment. Analysis of oil hydrocarbons with FTIR method revealed a significant number of oxygen-containing compounds, which are the hydrogenolysis products of structural fragments formed after destruction of kerogen and high-molecular components of oil. The gas chromatography-mass spectroscopy (GC-MS) method was applied to present the changes in the composition of mono-and dibenzothiophenes, which indicate conversion of heavy components into lighter aromatic hydrocarbons. The specific features of transforming trace elements in rock samples, asphaltenes, and carbene-carboids were observed by using the isotopic mass-spectrometry method.