In
this study, the
specific features
of Ashal’cha heavy oil conversion were revealed. The hydrothermal
catalytic experiments were carried out in a CO2 environment
and in the presence of oil-soluble carboxylate metals such as Fe,
Co, and Cu at the temperature of 300 °C. The results have shown
that the catalyst and minerals of reservoir rocks have significant
impact on the transformation behavior of group, structural group,
and hydrocarbon compositions of oil. The most significant changes
in the composition of heavy oil were established after hydrothermal
treatment in the presence of a rock-forming additive, clay mineral
(kaolin), which are reflected in a significant increase in the content
of saturated and aromatic hydrocarbons and a decrease in the content
of resins and asphaltenes. Furthermore, the changes in the structure
of asphaltenes led to the increase of aromaticity and oxidation degrees.
It was found that the catalyst metals mainly concentrate on the asphaltene
structures and on the rock-forming reservoir minerals. It has been
shown that the concentration of Fe increases up to 5.84% and that
of Cu from 0 to 0.25% after catalytic treatment of oil with kaolin.
A similar change was observed in the asphaltene content of rock extracts
where Fe and Cu concentrations reach 1.38 and 0.31%, respectively,
with no Co presence in asphaltene content. The number of catalytically
active metals such as Ti, Fe, Cr, Mn, Co, Ni, Cu, Zr, and Ba was found
in the rock obtained after the experiment and the extraction of organic
matter. Moreover, a slight decrease from 2.27 to 1.93% in Fe concentration
included in the catalytic complex has been established with an increase
in Co and Cu concentrations, which were practically absent in the
original rock, to 0.036 and 0.038%, respectively. It has been established
as well that the studied metal complexes (Fe, Co, and Cu) with carboxylate
ligands can penetrate not only into the pore space of the rock but
also into asphaltenes, thereby allowing them to catalyze the process
of heavy oil upgrading under hydrothermal conditions.