Relevance. The need to establish the selective impact of individual structural parameters and heteroatomic functional groups in the structure of asphaltene molecules on their aggregation in order to develop effective ways to prevent sedimentation in technological equipment at the stages of production, transport and processing of heavy hydrocarbon raw materials. Aim. To establish the impact of the structural group composition, the concentration of basic nitrogen in asphaltene substances on their colloidal stability. Objects. Heavy oil of the Republic of Tatarstan (density at 20°C – 940,0 kg/m³; viscosity at 20°C – 742,9 cSt), model oil systems with a basic nitrogen content of 1, 2, 3 wt %, asphaltenes initial and model petroleum systems and their thermolysis products. Methods. Liquid adsorption chromatography, potentiometric titration, elemental analysis, cryoscopy in naphthalene, ¹H NMR spectroscopy, structural group analysis, spectrophotometry. Results. Synthetic asphaltene-like nitrogenous bases were obtained by thermolysis of model petroleum systems with different contents of basic nitrogen (quinoline) at 400°C for 4 hours. During thermolysis, 0.3–0.8 wt % of basic nitrogen is additionally incorporated into the molecular structure of synthetic asphaltene-like substances. The molecular weight of synthetic asphaltene-like substances is two times lower than that of the asphaltenes of the initial oil. With an increase in basic nitrogen in synthetic asphaltene-like substances, the aromaticity factor increases by 2–3% with a decrease in the proportion of paraffin carbon. It was established that asphaltenes from thermally converted oil are two times more resistant to sedimentation compared to the initial asphaltenes, due to a twofold decrease in their average molecular weight. It was shown that the sedimentation rate of synthetic asphaltene-like nitrogenous bases is two–three times lower compared to the initial asphaltenes. It was established that the colloidal stability of synthetic asphaltene-like substances increases with the growth in N_bas content in their molecular structure.