Abstract
The aim of this work is to establish the relationship between the chemical composition of heavy crude oil and its rheological response to organic solvents of different nature, as well as to quantitatively assess the degree of viscosity reduction. Comprehensive analytical methods (XRF, FTIR, SARA, gas chromatography) revealed that the studied crude oil is characterized by a paraffinic–resinous matrix enriched with heteroatoms and metals, which determines its extremely poor flowability. It was experimentally proven that the addition of 15 vol.% xylene at 25 °C reduces the oil viscosity by more than 150 times (from 3.3 × 105 to 2.19 × 10³ cP), whereas the use of naphtha provides only a 30-fold viscosity reduction. The combined application of a chemical reagent (xylene) and thermal treatment (up to 60°C) was shown to achieve a viscosity of approximately 4.1 × 10² cP, which is sufficient for efficient transportation. The obtained results confirm the key role of solvent type in modifying the rheological properties of heavy crude oils and demonstrate the potential of the developed chemical-thermal methods for improving their transportability.