Ashalcha oilfield in Tatarstan is one of the famous sites to investigate the extractions of heavy oils. Specifically, the In-Situ Combustion Lab in Kazan Federal University has been operating there for a few years.
Image Credit: Shutterstock.com/ Red ivory
On average, there are one sulfur and one nitrogen atom and five oxygen atoms per resin molecule. In the course of transformation under the action of a catalytic agent and a hydrogen donor, the content of heteroatoms (sulfur, nitrogen and oxygen) in a much larger number of structural blocks of resin molecules decreases.
Irek Mukhamatdinov, Senior Research Associate, Kazan Federal University
“Resin molecules are mainly represented by mono- and two-block structures with a predominance of aromatic rings over naphthenic ones, with long paraffin chains,” added Mukhamatdinov.
As a result of thermal steam treatment with a catalyst and a hydrogen donor, the fraction of atoms in paraffinic and naphthenic fragments decreases, while in aromatic fragments it increases, which confirms the fact that an increase in the aromaticity and a decrease in the aliphaticity of oil take place during its hydrothermal transformations.
Alexey Vakhin, Study Co-Author and Head, In-Situ Combustion Lab, Kazan Federal University
The study enabled the scientists to identify the distribution of resin fractions. The fraction was yielded by liquid-adsorption chromatography, extracted using individual solvents and their binary mixtures in different proportions.
The results of MALDI spectroscopy uncovered a decline in the molecular weight of all resin fractions following catalytic treatment, primarily with a hydrogen donor.
“Elemental analysis data indicate a decrease in the H / C ratio for resin fractions as a result of the removal of alkyl substituents in resins and asphaltenes. The data of 1H NMR spectroscopy of resin fractions indicate an increase in the aliphatic hydrogen index during catalytic aquathermolysis in the high-molecular part of resins R3 and R4,” concluded Mukhamatdinov.
This technology is relatively cost-effective. Researchers have planned to use new catalysts in Ashalcha soon.
Journal Reference:
Mukhamatdinov, I. I., et al. (2021) Transformation of Resinous Components of the Ashalcha Field Oil during Catalytic Aquathermolysis in the Presence of a Cobalt-Containing Catalyst Precursor. Catalysts. doi.org/10.3390/catal11060745.