Transformation of Carbon-Rich Organic Components of a Domanik Rock in Sub- and Supercritical Aqueous Fluids

Abstract

Abstract: The paper identifies major features that distinguish the transformation of organic matter (OM) of rocks in the Semiluki (Domanik) deposits into solid, liquid, and gaseous products when exposed to sub- and supercritical water under various temperature and pressure conditions. To this end, a set of modern instrumental methods were used, namely: Rock–Eval, elemental analysis, GC, GC/MS, IR spectroscopy, XRD, and ICP-MS. The degradation of high-molecular-weight bituminous components and the decomposition of kerogen affect the yield of oil extracts from the rock and increase the proportion of saturated and aromatic hydrocarbons in the extracts. In the molecular composition of the extracts, an increase is observed in the concentrations of light C11–C18n-alkanes, C11–C12 alkyltrimethylbenzenes, naphthalenes, and phenanthrenes. Structural changes in asphaltenes are associated with an increase in their aromaticity and oxidation level, as well as with structural transformations in the vanadyl-porphyrin complexes. It was found that the oxidative degradation, desulfurization, and hydrolysis of carbon-rich components of organic matter are more vigorous in supercritical aqueous fluids than in subcritical water. In addition, a supercritical aqueous fluid promotes structural and phase transformations of rock minerals, in particular the isolation of a separate montmorillonite phase from a mica structure.