No 2 (2024)

The influence of ultrasonic treatment, a polymer additive, and their combined effect on the structural and rheological properties of high paraffin, low-resin oil and the composition of separated sediments is studied. The oil was processed in the ultrasonic field (with the field intensity of 6 W/cm², the frequency of 22 kHz, and the time of 1–10 min). The sedimentation process was carried out at an ambient temperature of 30°С and a coldfinger temperature of 5°С. A Brookfield DV-III ULTRA rotary viscometer was used to determine the viscosity-temperature parameters of the oil. Ultrasonic treatment for 1 min and a polymer additive (0.05 wt%) leads to a decrease in the viscosity by a factor of 5 and in pour point by 8°C. The introduction of the additive and the complex effect contribute to changes of the molecular weight distribution of n-alkanes in the sediments, viz. the second distribution maximum shifts to the region of higher molecular weight components and the concentration of n-alkanes ∑С₁₇Н₃₆–С₃₃ Н₆₈ increases.

Using the voltammetric method of oxygen electroreduction, an analysis of the antioxidant activity of resin-asphaltene components isolated from 2 crude oils of different compositions before and after exposure to a magnetic field was carried out. For the studied asphaltenes, weakly polar and polar resins, an increase or decrease in antioxidant activity is observed with increasing sample concentration in the background electrolyte solution. Petroleum antioxidants are part of a complex colloidal structural system and are associated with it by associative interactions that arise as a result of changes in the size and activity of associates of the petroleum system as a whole.

The influence of the duration of thermal action on the composition of cracking products of resins, asphaltenes and their mixture, isolated from methane heavy crude oil of Zyuzeevskoye oil field was studied. Cracking was performed in a closed reactor at 450°С for 60, 90 and 120 min. Data on the mass balance of the process, composition of hydrocarbons and sulfur-containing compounds in the cracking products were obtained. It was shown that the yields of coke increased with the process duration in the cracking of every studied material. The joint presence of resins and asphaltenes in a mixture changed the direction of thermal transformations of these components in the cracking process.

The composition of the oil shale cracking products (OS) from the Kashpirskoe deposit, as well as kerogen isolated from it, has been studied. The influence of OS mineral components on the material balance and cracking products composition is shown. It has been established that the amount of gaseous and solid products in kerogen cracking products decreases, and the yield of liquid products increases. Removal of mineral components from OS leads to an increase in oil content and a decrease in asphaltenes in liquid cracking products, the resin content changes slightly, and the yield of light fractions increases. The peculiarities of the influence of mineral components on the structural-group characteristics of resins and asphaltenes of liquid cracking products have been established. The absence of mineral components leads to enlargement of resin molecules; asphaltene molecules, on the contrary, become more compact.

The interaction of humic acids (HA) isolated from oxidized brown coal with the polyaromatic hydrocarbon naphthalene has been studied. The electron-donating properties of HA were evaluated by the intensity of electronic transitions in the UV region and the calculated descriptors. The modification of the HA structure was carried out by the method of mechanical activation (MA) under alkaline and oxidative conditions. A significant increase in the proportion of aromatic and oxidized fragments in the HA structure after MA under oxidative conditions increased the intensity of binding of HA to naphthalene. A significant increase in the adsorption capacity of mechanoactivated HA in a dispersive aqueous medium with naphthalene has been shown.

The composition of biomarkers of the Upper Jurassic rocks of the Vostochno-Payduginskaya exploration well of the section of the Maryanovskaya and Naunaksk formations was investigated. The conditions of organic matter (OM) sedimentation were characterized based on data on the hydrocarbon composition, namely: the distribution of normal and isoprenoid alkanes, phenanthrenes, steranes, hopanes, alicyclic and aromatic hydrocarbons. It was found out that organic matter (OM) was deposited throughout the section under study under oxidizing conditions. The sediments of the Naunaksk formation were formed in a shallow basin uncontaminated with hydrogen sulfide, while the OM of the Maryanovsk formation was formed in lacustrine environment. The presence of low concentrations of gammacerane in the Maryanovsk formation and the lower parts of the Naunaksk formation indicates weakly saline waters of the sedimentation basin during this period. The participation of higher plants in the formation of the OM composition of the Naunaksk rocks is evidenced by the high concentrations of cadalene, retene, and the presence of simonellite and C₂₅ and C₂₇ n-alkanes.

Samples of cryogels based on aqueous solutions of polyvinyl alcohol were investigated. The molecular weights of cryogel samples varied from 25 × 10³ to 60 × 10³. It has been found out that the ultimate strength of dry briquettes increases from 1.2 to 3.7 MPa with an increase in the polymer molecular weight. The resulted briquettes can be used, for example, as a proper domestic or industrial fuel.