Abstract
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.
Highlights
In recent years, the share of unconventional hydrocarbon resources from shale deposits in the structure of world oil production has been increasing [1,2,3]
Our work has led us to conclude that subcritical water (sub-CW) and supercritical water (SCW) provide conduction of intensive processes
Our work has led us to conclude that sub-CW and SCW provide conduction of intensive on transformation of high-molecular components of heavy oil and insoluble kerogen of Domanic processes on transformation of high-molecular components of heavy oil and insoluble kerogen of shales into light mobile crude oil
Summary
The share of unconventional hydrocarbon resources from shale deposits in the structure of world oil production has been increasing [1,2,3]. Low-permeable organic-rich Bazhen formations of West Siberia and Domanic deposits of Volga–Ural petroleum province correspond to such resources in Russia [4,5]. Domanic organic-rich shales are oil-generating source rocks [6]. A specific feature of such sedimentary rocks is the coexistence of free hydrocarbons and insoluble organic matter (OM), such as kerogen. The latter is an irregular structured “geopolymer” that generates oil and contains significant total organic content in sedimentary rocks [7,8].
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