Relevance. Operation of solid municipal waste landfills leads to soil degradation and a decrease in its fertility. Studying the impact of heavy metals on the ecology of landfill soils and soils of adjacent territories is important, since the accumulation of high concentrations of heavy metals can lead to disruption of the ecological and agricultural functions of the soil. Aim. To assess the contamination of soils by heavy metals at the solid municipal waste landfill in the city of Rostov-on-Don. Objects. The studied soil samples taken from the center of the landfill were compared to soils of the adjacent territory at different distances and directions relative to the center of the landfill. Methods. Gross contents of heavy metals and metalloids (V, Cr, Co, Ni, Cu, Zn, As, Sr, Pb, Rb, Zr, Ba) were studied using the X-ray fluorescence method. The obtained values were used to calculate the pollution indices: background enrichment coefficient, individual unified pollution index, geoaccumulation index, pollution load index, Nemerov pollution index, potential ecological risk index, pollution protection index, pollution probability index, and general pollution degree index. These indicators were used to determine the pollution degree of the studied territories. Results: The excess of Cr, Ni, Cu, Zn, As and Pb according to the MAC at the landfill from the control was determined. A very high concentration of heavy metals and metalloids compared to the MAC and background was found in the center and close to the center of the landfill, indicating the anthropogenic contribution of these elements. The evaluation of the results showed that the pollution load index is more reliable for assessing the pollution of the landfill and the adjacent territory with heavy metals. When compared, the used indices and pollution coefficients formed the following series: pollution load index>general pollution degree index>Nemerov pollution index>pollution probability index>pollution protection index>potential ecological risk index=background enrichment coefficient. The adjacent territory of the landfill was polluted to a lesser extent. The applied indices and coefficients can be used in environmental assessment, as well as in monitoring and for preventing soil pollution with heavy metals and metalloids. For citation: Kucherova A.V., Minnikova T.V., Kolesnikov S.I., Sherstnev A.K. Assessment of heavy metal pollution of soils of a municipal solid waste landfill of the city of Rostov-on-Don. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 90–101. http://doi.org/10.18799/24131830/2026/8/5062
Relevance. This article addresses the problem of improving the reliability and accuracy of sorting timber conveyors with a chain load-bearing element equipped with a variable-frequency asynchronous electric drive. An increase in the length of the working section of an extended timber-sorting conveyor leads to a rise in the mass of moving parts, a stronger influence of the viscoelastic properties of the chain, and greater complexity of transient processes during start-up. As a result, dynamic jerks, wave-like tension fluctuations, and misalignment in the displacement of individual chain sections occur, which reduces equipment durability and impairs the precision of timber delivery to storage bins. The relevance of this study is determined by the need to maintain the design service life of the load-bearing chain (belt) as a key structural element. Aim. To investigate the motion dynamics of chain-type and belt-type sorting conveyors in order to establish the boundary conditions for the operation of the load-bearing section. Results and Conclusions. It has been established that the most hazardous operating mode is rapid conveyor start-up without mechanical vibration damping. The use of a fluid coupling reduces the initial tension peak and proves most effective during short start-ups (up to 10 s), as it smooths abrupt changes in the drive torque and diminishes the intensity of the initial tension wave. However, for extended conveyors, the action of a single fluid coupling is insufficient: in the region of the reflected wave at the end of the load-bearing chain, the systematic error in timber positioning may remain at an unacceptable level. The implementation of an S-shaped ramp function reduces the jerk at the initial start-up stage and, at the final stage, limits tension oscillations while maintaining acceptable sorting performance. To achieve the ultimate sorting accuracy on long conveyors, it is advisable to employ a closed-loop electric drive control system with displacement sensors for timber on the load-bearing chain and wireless data transmission; however, the implementation of such a solution would be technically complex and capital-intensive. The optimal outcome of applying a refined model of the mechanical part of an extended sorting conveyor to reduce excessive oscillations under the climatic conditions of Western and Central Siberia is achieved through coordinated control of the traction variable-speed electric drive in conjunction with an adjustable fluid coupling. For citation: Kladiev S.N., Sarbassova N.D., Umurzakova A.D., Odnokopylov G.I. Mathematical models of sorting conveyors with belt and chain carriers. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 153–167. http://doi.org/10.18799/24131830/2026/8/5753
Relevance. The use of distributed fiber-optic temperature sensors in oil production wells can improve the quality of data obtained during operation. Aim. To show that the captured temperature distribution contains random fluctuations, the magnitude of which is comparable to the magnitude of thermoanomalies caused by the filtration flow of oil in the reservoir. Methods. To reduce the noise of the original signal taken from a real oil well, various approximation methods: median smoothing, moving average, exponential smoothing, Fourier filtering, decision tree, random forest, adaptive boosting and Nadaraya–Watson kernel regression method, were analyzed. Results and conclusions. The authors analyzed the results of application of these types of signal post-processing in terms of the following parameters: accuracy of approximation of equilibrium geothermal distribution in the well sump, where analytical determination of temperature distribution is possible, smoothness of the approximating function, uniqueness of the solution and demandingness of computational resources. It is shown that the application of adaptive boosting and Fourier filtering for this problem gives the largest approximation errors. Median smoothing, exponential smoothing and random forest give similar results in accuracy and low computational costs. The first does not have smoothness of solution. The second one depends to a large extent on the tuning parameters and the obtained solution may be either noisy as well, or the smooth solution may exhibit systematic error caused by random deviations of the initial points. Such error can be compensated by additional averaging at the initial stages of exponential smoothing. The random forest approximation is also tuning dependent, and regions of overfitting where the approximation replicates the original signal may be adjacent to a very coarse approximation of the original signal; this always produces a new approximation at each generation. The best results were obtained by the Nadaraya–Watson kernel regression method, since the solution found has the lowest error, high smoothness and uniqueness, in contrast to machine learning methods. On the basis of analyzing the features of the algorithm of this method, as well as the machine representation of real numbers, we propose methods to improve the computational efficiency of the Nadaraya–Watson kernel regression. For citation: Nikulin I.L., Mishurinskikh S.V., Chudinov P.Yu., Semenov A.S., Melekhin A.A., Nikulina D.I. Approximation and noise reduction in oil well thermometry by distributed fiber optic sensors. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 77–89. http://doi.org/10.18799/24131830/2026/8/5054
Relevance. Utilization of associated petroleum gas at remote and offshore fields remains an unresolved problem due to the lack of cost‑effective small‑scale technologies. Associated petroleum gas flaring causes environmental damage and leads to the loss of valuable hydrocarbon feedstock. Gas‑to‑liquids technology enables the conversion of associated petroleum gas into synthetic liquid hydrocarbons suitable for blending with crude oil or for use as motor fuels. However, known GTL processes require complex catalytic systems and separate regeneration of components, which limits their application in field conditions. Aim. To develop a single‑stage gas-to-liquid process for producing synthetic liquid hydrocarbons from synthesis gas obtained by non‑catalytic oxidative conversion of associated petroleum gas using polyfunctional catalysts, and to substantiate the design of a two‑section reactor that allows separating regeneration of catalytic components without stopping the main production. Methods. Seven bifunctional catalysts based on Zn, Cu and Al oxides were synthesized. The optimal Zn‑Cu/Al₂O₃ sample (ZnO 25.10 wt %, CuO 64.86 wt %, Al₂O₃ 10.04 wt %) was mixed with a pentasil‑group zeolite catalyst (SiO₂/Al₂O₃=47). Experiments were carried out on a laboratory flow unit with a fixed catalyst bed by varying the synthesis gas composition (H₂/CO≈0.93 and 2.03). Based on the identified technical contradiction (deactivation of the oxide catalyst during zeolite regeneration), a two‑section reactor was designed to be placed in a 20‑ft sea container. Strength calculations were performed. Results and conclusions. It was experimentally found that the maximum hydrocarbon yield (2.14 g/h) at a CO conversion of 29.1% is achieved with a feed having H₂/CO≈0.93, which corresponds to the composition of synthesis gas from non‑catalytic partial oxidation of associated petroleum gas with air. The proposed two‑section reactor allows oxidative regeneration of the zeolite‑containing catalyst in one section without stopping the hydrocarbon synthesis in the other section. The reactor block is scalable from 10 to 40 million m³ of associated petroleum gas per year by simply increasing the number of container modules. The developed polyfunctional catalytic system Zn‑Cu/Al₂O₃ + high‑silica pentasil is effective for single‑stage production of gasoline‑range hydrocarbons from synthesis gas with a low H₂/CO ratio. The two‑section reactor removes the limitations associated with separate catalyst regeneration and is a key element of the containerized “Heat – Electricity – Synthetic hydrocarbons” gas-to-liquid unit. The technical solutions are protected by a patent and can be recommended for pilot‑industrial implementation at remote oil and gas fields. For citation: Buslaev G.V., Kuzmin A.M., Malova O.V., Lishchiner I.I., Boreiko D.A., Innovative two-section reactor and catalysts for synthetic liquid hydrocarbon production at the GTL “HES” unit from synthesis gas of non-catalytic oxidative conversion of associated petroleum gas. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 45–56. http://doi.org/10.18799/24131830/2026/8/5696
In 2022–2024, it was officially established that unconventional renewable energy sources (wind turbines and solar panels) in the foreseeable future (15–20 years) will not be able to replace traditional energy (thermal and nuclear power plants) due to the lack of powerful, reliable and safe electric energy storage systems. Therefore, coal-fired power plants in the coming decades will certainly generate large amounts of electricity not only in China, India, the USA and Poland, but also in many other countries. In this regard, the world-class scientific problem is environmental pollution by coal combustion products (flue gases from coal-fired power plants). This problem can be solved by burning coal in the furnaces of steam and hot water boilers mixed with biomass (wood in the first place). But wood burning in the furnaces of boiler installations so far in most real technologies leads to intensive slagging of heating surfaces. Therefore, an urgent task, the solution of which can ensure the transition to environmentally friendly and resource-saving coal-fired power in the future, is the task of substantiating the parameters of ignition and combustion of wood biomass particles. Aim. To determine the combustion modes of wood biomass particles of different sizes during high-temperature heating. Object. Wood particles (pine) of cubic shape of three characteristic sizes. Method. To determine the ignition and combustion modes of cubic wood particles under high-temperature heating conditions, a special experimental setup with laser illumination was used. Results. A conventional temperature boundary of Tcr=908 K was established for the transition between two ignition modes (gas-phase and heterogeneous) for pine wood biomass particles. It was also shown that the characteristic particle size of the wood (in the studied size range, L=4–8 mm) has no significant effect on the characteristics and conditions of the transition from one ignition mode to another. It was also experimentally established that, at relatively low oxidizer temperatures, the difference in ignition delay times for different ignition modes with a characteristic particle size of L=8 mm can reach 10%. For citation: Baranova (Kostoreva) A.A., Syrodoy S.V., Solodovnikova (Kostoreva) Zh.A., Omarov A.A., Nekrasov S.S., Senchikhin D.K. Oxidizer temperature effect on the modes of ignition of wood biomass particles. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 32–44. http://doi.org/10.18799/24131830/2026/8/5436
Relevance. Disruptions in technological processes, along with leaks and spills at industrial facilities, result in soil contamination by petroleum hydrocarbons. When oil enters the soil, it reduces air and water permeability, leading to soil ecosystem degradation, including microorganisms and vegetation. Therefore, the search for effective and safe methods to restore contaminated soils is highly relevant. Aim. To investigate the potential for remediating soil contaminated with used motor oil through biostimulation, using sheep bone biochar and manure as biostimulants, and assess the impact of human intervention. Objects. Soil contaminated with used motor oil at the Ulaanbaatar locomotive depot. Sheep manure provided nutrients, while bone biochar improved air exchange. The experiment included four variants: control, biochar, manure, and their combination. Bioreactors were placed outdoors for 365 days, with one group regularly moistened and stirred, while the other remained untreated. Methods. Total petroleum hydrocarbons were determined by ultrasonic extraction; light and heavy hydrocarbons were analyzed by gas chromatography, and heavy metals were measured using optical emission spectroscopy. Soil characteristics were determined using standard methods in Mongolia. Hydrocarbon-oxidizing bacteria in the contaminated soil were assessed using a motor oil and gasoline (1:1) mixture as a carbon source. Results and conclusions. A 365-day biostimulation experiment on soil contaminated with used motor oil showed that treating control soil without additives resulted in a 6% increase in biodegradation, highlighting the importance of human intervention. Adding biochar and sheep manure improved biodegradation: biochar increased it from 13.4 to 18.9%, manure from 11.5 to 15.9%, and their combined use raised efficiency from 22.6 to 27.3%. Heavy fractions of used motor oil were biodegraded by indigenous hydrocarbon-oxidizing bacteria and turned into lighter fractions, especially with biochar (4.7% degradation). The best results were obtained with the combined application of biostimulants. For citation: Nomintuya A., Buyan Ch. Remediation of soils contaminated with used motor oil by biostimulation method. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 227–243. http://doi.org/10.18799/24131830/2026/8/5037
Relevance. The need to obtain factual data on the composition of volatiles in mineral formation processes in oxidation zones of copper ore deposits. The new data obtained can be used to adjust the holistic model of hypergene secondary ore formation. Aim. To determine the composition of volatile components preserved in structural channels and inclusions in dioptase and in inclusions of coexisting calcite. Object. Altyn-Tyube deposit (Karaganda region, Kazakhstan). Methods. The forms of occurrence of molecules of volatile components in the silicate framework were determined by the method of Raman spectroscopy. The bulk composition of the fluid was analyzed by the method of non-pyrolysis gas chromatography-mass spectrometry with impact destruction of the sample. Results and conclusions. In the composition of the volatiles extracted from dioptase, 277 individual components were found, and from calcite 269. Based on these data, it was shown that the volatiles in dioptase and the calcite coexisting with it represent a complex multicomponent mineral-forming system. The dominant fluid component in them is water, its content in dioptase is 78.3, and in calcite 55.1 rel. %. Carbon dioxide, hydrocarbons, S-, N- and halogen-containing compounds were found in dioptase. The share of carbon dioxide exceeds 13, and hydrocarbons and their derivatives 7 rel. %. The spectrum of detected organic compounds includes oxygen-free aliphatic and cyclic hydrocarbons (paraffins, olefins, cyclic alkanes (naphthenes) and alkenes, arenes, polycyclic aromatic hydrocarbons), oxygenated hydrocarbons (alcohols, ethers, furans, dioxins, dioxanes, aldehydes, ketones, carboxylic acids). Sulfonated compounds in the gas mixture from dioptase are represented by oxide (O2S, 0.448 rel. %), sulfides (hydrogen sulfide, carbonyl sulfide, dimethyl sulfide, carbon disulfide, dimethyl disulfide), thiols (methyl mercaptan), thiophenes and 2-mercapto-2-phenylacetic acid (C8H8O2S). The composition of nitrogenated compounds includes molecular nitrogen (N2, 0.205 rel. %), ammonia, isocyanates (CHNO and C2H3NO), nitriles (C2H3N, C3H5N, C7H5N), amines (C3H5N), 1,4-, 1,3-, 1,2-diazines, pyrrole, amides (C2H5NO-C12H25NO), pyridines (C5H5N-C6H7N), 2-methylpyrazine, pyrazole, 2,5-pyrrolidinedione, caprolactam and 4‑methylaminophenol. Among the volatiles of dioptase and calcite, the same halogenated compound 1-chlorobutane (C4H9Cl) was recorded. It was established that the aqueous solutions that formed the dioptase-calcite mineralization at the Altyn-Tyube deposit had a similar species diversity of gas phases, but with a difference in concentrations between them. For citation: Bulbak T.A., Tomilenko A.A., Zatolokina K.I., Shaparenko E.O. Volatile components in dioptase (Altyn-Tyube, Kazakhstan) and coexisting calcite according to pyrolysis-free gas chromatography-mass spectrometry data. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 140–152. DOI: http://doi.org/10.18799/24131830/2026/8/5112
Relevance. Acid treatment of the bottomhole zone of wells in carbonate reservoirs of the Middle East, characterized by significant layer-by-layer heterogeneity and low filtration-capacity properties, is associated with a number of complications. This negatively affects the stimulation of oil inflow, restoration of productivity of producing wells and injectivity of injection wells. Consideration of technological solutions and approaches to acidizing in carbonate reservoir conditions is of research and practical interest. Aim. To study the capabilities and features of modern technologies for acidizing the bottomhole zone of wells in Middle East carbonate reservoirs. Methods. Review of modern scientific literature on acidizing carbonate reservoirs, analysis of features and a summary of the main ways to solve problematic aspects of acidizing carbonate reservoirs in the Middle East. Results and conclusions. The paper describes the characteristics of Middle East carbonate reservoirs, including high temperature, salinity, carbonate rock purity, layered heterogeneity, low permeability, and great depth. The paper introduces the factors influencing the effectiveness of acid treatment. To improve the effectiveness of acid treatment, it is recommended to use the following: delayed and diverting acid systems based on gel, foam, micro- and nanoemulsions, viscoelastic surfactants, and foamed viscoelastic surfactants; diverters in the form of biodegradable, multimodal mixtures of particles and fibers; multicomponent and multistage treatment, and hybrid and integrated technologies. It is clarified that acid fracturing technologies in horizontal and multilateral wells involve targeted delivery of viscoelastic surfactants using coiled tubing systems, mechanical diversion, or drill pipe with a point-type downhole tool. To maintain stable fracture conductivity during acid fracturing, hybrid multi-stage technologies are required, such as the use of guar gel-based fracturing fluid and a retarded acid system in conjunction with proppant, or the use of chelating agents. It is noted that the weakening of the mechanical strength of carbonate rocks during acid treatment can be compensated for by using consolidating agents. For citation: Almohammad Alnayef M., Bezverkhaya E.V., Gnidan E.V. Modern technologies for acid treatment of carbonate reservoirs in the Middle East. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vo. 337, no. 8, pp. 112–128. http://doi.org/10.18799/24131830/2026/8/5390
Relevance. Growing need for energy-efficient and renewable energy sources, such as low-potential heat from the Earth. Horizontal ground heat exchangers are one of the key elements of geothermal heat pumps, and their efficiency largely depends on climatic conditions and seasonal temperature fluctuations. In this regard, it is an important task to predict their thermal conditions in order to optimize design and operation in specific regions. Aim. To study the thermal modes of operation of a horizontal ground heat exchanger in conditions of seasonal temperature fluctuations in Western Siberia. Object. A typical design of a surface-type geothermal heat exchanger consisting of a polypropylene pipeline forming a closed heat exchange system and a heat-conducting filling – a specially prepared sand layer surrounding the pipelines. Methods. To solve the problem, the COMSOL Multiphysics multiphysical modeling complex was used with application of the Heat Transfer in Solids and Fluids module, designed to analyze heat transfer processes in solids and liquids. The calculations were performed on a finite element grid constructed using the Delaunay method. The model was verified by comparing it with analytical solutions and data from literary sources. Results. Detailed temperature distributions in the soil mass surrounding the heat exchanger were obtained with monthly increments throughout the year. It was established that the amplitude of seasonal temperature fluctuations at a depth of 1.5 m is up to 25°C, whereas at a depth of 3 m it does not exceed 5–7°C with a phase delay of 2–3 months. The maximum heat flows (up to 15.6 kW) are observed in the summer months, the minimum (about 8.5 kW) – in the winter months. For citation: Polovnikov V.Yu., Lyubivy E.V., Fedorchenko I.P. Numerical analysis of the effect of seasonal temperature fluctuations on the thermal modes of horizontal ground heat exchangers in Western Siberia. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 57–64. http://doi.org/10.18799/24131830/2026/8/5412
Relevance. The oil and gas industry remains strategically important to the global economy, and the efficiency of field development is directly determined by the accuracy of reservoir potential assessment and geological system behavior prediction. However, reliable quantitative assessment of reservoir productivity is hampered by high geological heterogeneity, limited and diverse geological and production data, and the difficulty of integrating static and dynamic parameters. With the industry digitalization, machine learning methods are emerging as a promising tool capable of complementing or partially replacing classic hydrodynamic simulators by identifying complex nonlinear relationships between input geological characteristics and output development indicators. Aim. To critically systematize global experience in applying machine learning methods to assess reservoir potential and forecast oil and gas field development indicators. Methods. Analysis of scientific publications devoted to the application of machine learning methods, including neural networks, ensemble algorithms, probabilistic and hybrid models, to forecasting flow rates, cumulative production, and pressure. The characteristics of the input data used, approaches to model training, and metrics for assessing forecast quality are discussed. Results and conclusions. Machine learning methods have been shown to significantly accelerate reservoir potential assessment while maintaining accuracy comparable to hydrodynamic models. They effectively identify complex relationships between geological characteristics and dynamic system responses, making them a promising tool for the rapid analysis of development scenarios. However, key limitations remain sensitivity to the quality of input data and the limited nature of training samples. The authors note a trend toward hybrid approaches combining machine learning and physical and mathematical modeling, improving the robustness and interpretability of results. Despite the high level of automation, expert participation remains critical at the stages of data preparation, feature selection, and results interpretation. For citation: Piskunov S.A., Truhachev M.S., Rukavishnikov V.S., Davoodi S. Machine learning for reservoir potential assessment: a critical review of established and promising methods. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 168–183. http://doi.org/10.18799/24131830/2026/8/5657
Relevance. New type of cooling of a power oil transformer with SF6 bubbles is proposed and therefore it is necessary to develop a mathematical model for selecting the optimal operating mode of a compressor bubbling SF6 gas. In the process of overheating of a power oil transformer, a cooling system is activated using floating SF6 bubbles, as a result, the pressure in the working area decreases, it becomes lower than the saturation pressure of the transformer oil with SF6 gas, i. e. when SF6 gas passes through the transformer oil inside the working area, an area of heat exchange of transformer oil, SF6 gas and transformer windings occurs. In this situation, each of the phases has a decisive effect on the creation of a thermal field in the working area, due to the manifestation of thermodynamic effects and the heat of degassing of the transformer oil. The formation of the temperature field is affected by various parameters: the local initial temperature on the transformer windings, the content of dissolved SF6 gas in the transformer oil, as well as the ratio of pressures in the transformer oil reservoir and the saturation pressure of the transformer oil with SF6 gas, etc. Thermal processes provide information on the current state of the power oil transformer. Aim. To formulate and solve the temperature problem of the transformer oil cooling. The object of the study is an industrial power oil transformer and a gas-insulated cooling system. Methods. One of the key aspects of ensuring the safety and efficiency of power oil transformers is the analysis of their temperature conditions. Under normal and especially emergency conditions of transformer operation, especially in gas-insulated cooling systems, transformer oil decomposes, which leads to gas formation. These processes cause changes in the temperature distribution inside the transformer, providing valuable data for diagnosing the causes of accidents. Results. The author has determined the dependences of temperature conditions on the operating time and operating conditions, which served as the basis for software development. Based on the identified patterns of heat transfer by SF6 gas in liquid insulators, it is possible to develop industrial solutions with adjustable diffusion and heat transfer parameters, as well as optimize the operating modes of these systems, taking into account the dynamics of chemical reactions and their rates. This allows for increased reliability and efficiency of transformer equipment operation. For citation: Khismatullin A.S. Development of a model of a cooling system for a power oil transformer based on sulfur hexafluoride. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 16–23. https://doi.org/10.18799/24131830/2026/8/5058
Abstract. Relevance. The titanium industry is a strategically important area of development for any modern country. Aerospace, medical, food and other material-intensive industries are just a short list of consumers of titanium compounds. Most of the titanium reserves in the Russian Federation are presented in the form of quartz-leucoxene sandstones, the processing of which allows obtaining titanium tetrachloride, a precursor for the synthesis of titanium dioxide. Objective. To study the stability of aqueous solutions of titanium tetrachloride and to assess the effect of silicon tetrachloride impurity on the rate of hydrolytic decomposition of TiCl4. Methods. To study the hydrolysis processes, spectrophotometry and magnetic plasma atomic emission spectroscopy were used. Results and conclusions. The hydrolysis process of aqueous hydrochloric acid solutions of TiCl4 was studied. It was proven that the hydrolysis process accelerates as the concentration of TiCl4 in the solution decreases, while TiCl4 solutions with concentrations of 2.5 - 10.0 wt. % are actively hydrolyzed during the first day and are not suitable for transportation or storage. It has been proven that heating a TiCl4 solution increases the rate of titanium tetrachloride hydrolysis by 3 orders of magnitude. Changing the intensity and temperature of heating will allow regulating the rate of hydrochloric acid release (the rate of hydrolytic decomposition). It has been established that the admixture of silicon tetrachloride in an amount greater than 0.4% by weight of SiCl4 leads not only to the acceleration of the hydrolytic decomposition of titanium tetrachloride, but also to the polycondensation/polymerization of the resulting active silicic acid with the formation of gel-like structures. The drop in the concentrations of titanium compounds during the hydrolysis of silicon-containing solutions was up to 10% TiCl4 for every 0.5% SiCl4. The data obtained in the work can be used to obtain industrial titanium dioxide or in the production of complex titanium-containing coagulants. Relevance. The titanium industry is a strategically important area of development for any modern country. Aerospace, medical, food and other material-intensive industries are just a short list of consumers of titanium compounds. Most of the titanium reserves in the Russian Federation are presented in the form of quartz-leucoxene sandstones, the processing of which allows obtaining titanium tetrachloride, a precursor for the synthesis of titanium dioxide. Aim. To study the stability of aqueous solutions of titanium tetrachloride and to assess the effect of silicon tetrachloride impurity on the rate of hydrolytic decomposition of TiCl4. Methods. To study hydrolysis, spectrophotometry and magnetic plasma atomic emission spectroscopy were used. Results and conclusions. The author has studied hydrolysis of aqueous hydrochloric acid solutions of TiCl4. It was proven that hydrolysis accelerates as the concentration of TiCl4 in the solution decreases, while TiCl4 solutions with concentrations of 2.5–10.0 wt % are actively hydrolyzed during the first day and are not suitable for transportation or storage. Defined that heating a TiCl4 solution increases the rate of titanium tetrachloride hydrolysis by three orders of magnitude. Changing the intensity and temperature of heating will allow regulating the rate of hydrochloric acid release (the rate of hydrolytic decomposition). It was established that the admixture of silicon tetrachloride in an amount greater than 0.4 wt % of SiCl4 leads not only to the acceleration of the hydrolytic decomposition of titanium tetrachloride, but also to the polycondensation/polymerization of the resulting active silicic acid with the formation of gel-like structures. The drop in the concentrations of titanium compounds during the hydrolysis of silicon-containing solutions was up to 10% TiCl4 for every 0.5% SiCl4. The data obtained in the work can be used to produce industrial titanium dioxide or in the production of complex titanium-containing coagulants. For citation: Kuzin E.N. Stability of hydrochloric acid titanium-containing solutions for processing quartz-leucoxene concentrate by selective chlorination. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 7–15. https://doi.org/10.18799/24131830/2026/8/5052
Relevance. This paper addresses the challenge of classifying and predicting hydraulic flow units in reservoirs, particularly in heterogeneous formations like the Cuu Long basin, offshore Vietnam. Integrating machine learning techniques offers a modern and efficient approach to reservoir characterization, which is crucial for improving permeability estimation and reducing uncertainty in reservoir modeling. Aim. To suggest a novel strategy to enhance the estimation of permeability and provide a more continuous geological profile for reservoir engineers. Objects. Core samples and well log data collected from 42 wells in the Cuu Long basin, offshore Vietnam. Methods. Machine learning techniques – both unsupervised and supervised were applied to predict permeability from well log data. Results. The study found that Fuzzy C-means clustering provided the optimal classification of hydraulic flow units, with 5 HUs being the best division for sedimentary reservoirs in the Cuu Long Basin. Among supervised learning models, Random Forest performed the best in clustering HUs, achieving an accuracy of 93% in training and 86% in testing, outperforming Boosted Tree, Artificial Neural Network, and Support Vector Machine. The integration of core and well log data improved hydraulic flow units classification and permeability prediction in heterogeneous reservoirs, providing a valuable tool for improved reservoir characterization and management in the Cuu Long basin and similar geological settings. For citation: Vu Hong Duong, Nguyen Thanh Tung, Nguyen Minh Hoa, Nguyen Danh Lam, Ha Quoc Dat, Nguyen Xuan Duy. Permeability prediction from well-logs by applying hydraulic flow unit and machine learning: a case study of Cuu Long basin, offshore Vietnam. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 211–226. http://doi.org/10.18799/24131830/2026/8/5049
Relevance. In the modern world, due to the growth of industrialization and an increase in wastewater disposal, the problem of treating wastewater contaminated with petroleum products is becoming increasingly important. Wastewater treatment is a complex and urgent task that requires an integrated approach. As a rule, the main stage is physico-chemical purification, in particular coagulation. Often, traditional reagents based on metal salts (aluminum, iron, etc.) are characterized by low efficiency due to their narrow operating pH range, which in its turn does not allow them to achieve the required standards, the use of some in several cases is economically unprofitable. In this regard, there is an urgent need to create and implement new technical solutions. Aim. To evaluate the effectiveness of using complex titanium-containing reagents for wastewater treatment of washing vehicles contaminated with petroleum products. Results and conclusions. It has been proven that the use of a complex sulfate-chloride coagulant at a dose of 75 mg/dm3 (in terms of the amount of Al2O3 and TiO2 oxides) demonstrates the greatest efficiency in removing suspended solids (98.4%), petroleum products (78.4%) and reducing chemical oxygen demand (34.5%) in comparison with both traditional aluminum and iron-containing coagulants, and aluminum sulfate modified by the hydrolysis products of titanium tetrachloride and titanyl sulfate in amounts from 1 to 7%. It was found that the use of complex sulfate-chloride coagulant significantly speeds up sedimentation of the resulting coagulation sludge and reduces its volume, which helps to reduce the load and increase the efficiency of the filtration equipment. For citation: Peresunko Yu.D., Azopkov S.V., Kruchinina N.E. Application of complex titanium-containing coagulants in wastewater treatment from petroleum products. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 24–31. xttp://doi.org/10.18799/24131830/2026/8/5015
Relevance. Ensuring industrial safety at oil and gas facilities requires simultaneous monitoring of process parameters, equipment status, personnel actions, and early warning signs of emergency situations. In practice, this data often remains dispersed among independent subsystems: video surveillance, fire alarms, gas analysis, access control systems, and industrial automation. As a result, the operator receives not a unified risk picture, but a set of disparate signals that must be quickly correlated by time, location, and meaning. Aim. To substantiate an approach to creating a local multimodal intelligent decision support system that combines video, audio and sensory data. Methods. The methodological basis of the work is system analysis, conceptual modeling, multimodal data fusion, and microservice architecture principles. Results. The authors have proposed a system model, including a data collection layer, preprocessing, computer vision, audio analytics, and sensor diagnostics modules, a RabbitMQ message bus, a correlation aggregator, a decision support module, and an operator interface. It is demonstrated that cross-verification of events across multiple independent sources can improve the reliability of alarm messages and reduce operator workload. The scientific significance of this work lies in the formalization of an approach to the joint interpretation of heterogeneous data, while its practical significance lies in the feasibility of applying a local architecture to critical information infrastructure facilities. For citation: Chumakov K.V., Zhdanova A.O. Multimodal intelligent decision support system for improving industrial safety at oil and gas facilities. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 184–199. http://doi.org/10.18799/24131830/2026/8/5806
Relevance. Mercury is one of the dangerous toxicants. And the food products are the main source of intake for the human body. Bioindication of mercury content in living organisms consumed by people allows identifying both the degree of their mercury contamination and the possible risks to the preservation of bioresources, and provides insights into the presence or absence of human health risks. Aim. To assess the safety of freshwater animals (fish, crayfish) consumed by residents of the territory affected by mining activities at the Novo-Ursk polymetallic deposit, and to identify possible human health risks. Methods. The total Hg content was determined by the AAS method (analyzer "RA-915M" with the pyrolytic attachment "RP-91S", Lumex, Russia) according to the method M 03-09-2013. The geochemical indices: provisional tolerable daily intake, maximum permissible limit (CRlim), maximum permissible meals per month, target hazard quotient, were used to assess the risks of the fish and crayfish consumption impact on human health. Results. Mercury concentrations in the fish exceed the maximum permissible concentration only in predatory ones, sampled in 5 km from the mouth of the drainage stream into the Ur River. The Hg content in the crayfish, living in the flooded quarry of Ursk mine, is higher than the maximum permissible concentration. For these sampling sites and variety fauna, the provisional tolerable daily intake values close to its reference were also recorded, as well as a smaller number of safe consumption portions per month and excess of target hazard quotient (there is a risk of non-carcinogenic diseases). For the remaining sampling sites carried out in the ore conditions of the Novo-Ursk deposit, the small number of safe consumption portions per month recorded in accordance with the reference values maximum permissible concentration, provisional tolerable daily intake and target hazard quotient indicate the need to prohibit the consumption of fish because of its low safety. Thus, it is not recommended to eat fish caught from water bodies that are affected by the Novo-Ursk deposit. Mercury concentration in fish of only the area located above of dispersion halo of the Novo-Ursk deposit is standard for safe consumption. The maximum permissible concentration and target hazard quotient (long-term consumption) for fish and crayfish are more corresponding to the possibility of safe consumption of products, compared to the provisional tolerable daily intake. For citation: Gustaytis M.A., Myagkaya I.N. Human health risk assessment from consumption of freshwater fish and crayfish containing mercury. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 244–254. http://doi.org/10.18799/24131830/2026/8/5340
Relevance. Submersible electric centrifugal pumps are widely used in artificial lift oil production in Russia. Their geographic reach is extremely wide, from the far north to the Middle East. The surface equipment of these pumps is exposed to harsh climatic conditions. In winter, ambient temperatures can drop to –60°C. The most vulnerable component of the surface equipment of electric centrifugal pumps is the step-up transformer. Submersible pumps are often operated in intermittent mode due to the high gas-oil ratio. During pumping shutdowns, the gas content in the wellbore fluid decreases. In cold climates, the step-up transformer cools to low temperatures during the shutdown. This causes the oil in the transformer to thicken, disrupting oil circulation and impairing heat dissipation. After switching on, the oil around the transformer core heats up faster than the oil near the tank walls, causing localized overheating and thermal stress. Mechanical fastenings in the transformer structure weaken, and the insulating materials become increasingly brittle. Therefore, intermittent operation significantly reduces the transformer service life and leads to its rapid failure. Installing a high-voltage switch at the step-up transformer output allows the transformer to remain idle during operational pauses, avoiding thermal stress upon switching on. Aim. To study the temperature regime of the transformer during intermittent short-term operation; to develop a power supply system for a submersible electric motor that allows the transformer to remain idle during process pauses, which eliminates the impact of temperature stress on the step-up transformer at the moments of switching on during intermittent short-term operation of the well in low-temperature conditions. Methods. Methods for determining transformer temperature, thermal imaging control. Results. The authors have proposed a submersible electric motor power supply system that allows the transformer to remain idle during operational pauses. This eliminates the impact of thermal stress on the step-up transformer during short-term well operation in low-temperature conditions, reduces its wear, and increases its service life. For citation: Shaidullin V.F., Shumikhin A.Yu., Khakimyanov M.I. Operation of step-up transformers of submersible electric centrifugal pumping units in low temperature conditions. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 102–111. http://doi.org/10.18799/24131830/2026/8/5823
Relevance. High-paraffin, resinous crude oils are characterized by high viscosity and elevated pour points, which become particularly problematic under low-temperature conditions. These properties significantly complicate pipeline transportation due to increased hydraulic resistance, higher energy consumption, and flow instability. Therefore, improving the rheological properties of such oils is essential for ensuring efficient and reliable transportation. Effect of a magnetic field treatment and depressor additives are considered promising methods for viscosity and pour point reduction. Aim. To investigate the individual and combined effects of magnetic field treatment and the depressor additive Difron-3907 on the rheological properties of high-paraffin, resinous crude oil; to determine the optimal effect of a magnetic field exposure time, the effective additive concentration, and the efficiency of their combined application. Methods. Laboratory experiments were conducted using a Reotest viscometer. Oil viscosity was measured before and after effect of a magnetic field treatment and the addition of Difron-3907 at concentrations ranging from 100 to 700 ppm. Effect of a magnetic field exposure times varied between 5 and 25 minutes. The physicochemical properties of the crude oil sample were initially determined, and long-term viscosity stability was monitored over 25 days under optimal treatment conditions. Results and conclusions. 25-minute effect of a magnetic field treatment reduced oil viscosity from 2200 to 1000 mPa·s, corresponding to a 54.5% decrease. The addition of Difron-3907 at an optimal concentration of 700 ppm resulted in a viscosity reduction to 1210 mPa·s (approximately 45%). The highest efficiency was achieved through combined treatment: a 20-minute effect of a magnetic field exposure together with 350 ppm Difron-3907 reduced viscosity to 600 mPa·s, representing a 72.7% decrease. These findings demonstrate that the combined application of effect of a magnetic field waves and Difron-3907 significantly enhances the rheological properties of high-paraffin, resinous crude oils, contributing to reduced energy consumption and improved efficiency of pipeline transportation processes. For citation: Gurbanov G.R., Akhundova N.R. Investigation of the synchronous effect of a magnetic field and a depressor additive on the rheological parameters of high-paraffin crude oil. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 129–139. http://doi.org/10.18799/24131830/2026/8/5438
Relevance. Substantiating rational bottomhole pressure values is a critical task in monitoring and managing oil well operations. Uncontrolled reductions in bottomhole pressure aimed at creating high reservoir drawdowns and increasing oil inflow contribute to a number of negative factors both in the well itself and in the adjacent near-wellbore zone (oil degassing, reservoir void deformation, etc.). The most appropriate approach to substantiating rational bottomhole pressure values is the analysis of indicator diagrams obtained during actual well testing across a wide range of drawdowns. Currently, such studies are rarely conducted, and indirect approaches, often based on various types of modeling, are used to substantiate rational bottomhole pressure values. Existing approaches, however, typically rely on considering only one factor complicating oil inflow as bottomhole pressure decreases. This article is devoted to the development of a new approach to the substantiation of rational bottomhole pressures, which considers the geological and technological parameters of wells. Aim. Substantiation of rational and critical values of bottomhole pressure for real-life oil field conditions, considering the complex, in some cases multidirectional, relationship between its value and other geological and technological parameters of wells. Methods. Multiple regression analysis using a wide range of field indicators characterizing the non-stationary state of the "reservoir–wellbore" system. Results and conclusions. A series of multivariate statistical models were constructed, establishing the relationship between bottomhole pressure and a set of geological and technological parameters of wells. A detailed study of the statistical modeling, carried out based on cumulative correlation analysis, made it possible to substantiate the rational (8.3 MPa) and critical (6.3 MPa) values of bottomhole pressure for the conditions of the field under consideration. For citation: Mekhonoshin R.O., Ponomareva I.N. Alternative approach to justifying rational bottomhole pressures during the operation oil wells. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 65–76. http://doi.org/10.18799/24131830/2026/8/5377
Relevance. The reliability of borehole pumping units used for uranium in-situ leaching mining is largely determined by the performance of submersible electric motors. Operating a submersible electric motor in modes other than its nominal value reduces the expected service life of the equipment. Refining the probabilistic reliability model of electric motor, taking into account its load determined by the average well flow rate, leads to increased accuracy in calculating the need for new electric motors and directly impacts production profitability. Methods. Statistical methods, survival analysis, statistical hypothesis testing. Results and conclusions. For a previously obtained probabilistic reliability model of a submersible electric motor based on a mixture of two Weibull distributions, the parameter values were determined for groups of electric motors operating under different loads. The dependences of five reliability model parameters on the average flow rate were determined as piecewise linear approximations; their adequacy was confirmed using nonparametric goodness-of-fit tests. Based on the refined probabilistic reliability model, the dependence of the expected mean time to failure of a submersible electric motor on the average well flow rate was obtained. It was shown that operating an electric motor with flow rates significantly different from the nominal ones leads to a noticeable decrease in the mean time to failure. The resulting refined probabilistic reliability model can be used in information and control systems of a production complex to forecast the service life of submersible electric motors, as well as to calculate the need for electric motors required to replace failed ones over the planning horizon. For citation: Efremov A.A., Noskov M.D., Filipas A.A., Shchipkov А.А. Average flow rate effect on the reliability of submersible electric motors of borehole pumping units in uranium mining by the in-situ leaching method. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 200–210. http://doi.org/10.18799/24131830/2026/8/5495
