Abstract. Relevance. Potentially toxic elements serve as the most important indicators of environmental pollution, creating a potential risk for the ecology and health of the ecosystem, as well as humans in industrial regions. Soil is the main geochemical sink for various pollutants and provides a medium for the transport of many pollutants to the atmosphere, the hydropheric and biomass. Therefore, it is necessary to conduct a comprehensive study to assess geoecological risks from potentially toxic elements in soils.

Aim. Assessment of the potential geoecological risk of soil contamination on the territory of the industrial site of the Udachny Mining and Processing Division using various pollution assessment indices.

Objects. Dominant soil types in the northern taiga landscapes of the Daldyn kimberlite field.

Methods. Atomic absorption, statistical methods.

Results and conclusions. The author has carried out the assessment of potential sources of soil pollution and geoecological risks using such pollution indicators as the geoaccumulation index, Improved Nemerov index, pollution index, pollution load index, potential ecological risk. The soils of the study area are predominantly contaminated with Ni, Co, Cr and Mn. 19.51% of objects in the study area had a high potential environmental risk for Mn and Ni, and only 4.87% had a low potential environmental risk. Analysis of the spatial distribution of various pollution indices showed similar pictures. Local points with high values of pollution indices were identified. Hot spots were noted in the areas affected by the Udachny and Zarnitsa pipes dumps and tailings dump no. 2.

Relevance. The need to improve the accuracy and reliability of forecasting the productivity of gas and gas condensate wells in the long-term planning of gas production enterprises. To improve the accuracy and reliability of calculations of forecast flow rates, it is necessary to take into account changes in the filtration and capacitance properties of the formation in bottom-hole zones caused by the values of reservoir pressure and depression changing over time.

Aim. To determine the equations of real indicator curves of fluid inflow to a gas well, taking into account the dependence of the reservoir filtration and capacitance properties in bottom-hole zones on changing values of reservoir pressure and depression. To achieve this aim, the authors apply the working hypothesis that, firstly, in a hidden form, all the physical patterns of gas filtration to the well are contained in the accounting geological and field documentation accumulated during the operation of the well. Secondly, the equations of all real indicator curves can be approximated by the generalized Rawlins–Shellhardt equation proposed by the authors. Based on the results of processing real geological and field data from a number of wells, a new effect was discovered, showing that real indicator curves, unlike classical theoretical situations, can be described by non-monotonic dependences of flow rate on depression. The discovered new effect has important theoretical and practical significance for the oil and gas industry.

Objects. Equations of gas inflows to wells, approximated in the form of a generalized Rawlins–Shellhardt equation.

Methods. Methods of interpolation and approximation of field data, numerical integration, mathematical modeling methods, correlation and regression analyses, least squares method.

Results. For real indicator curves describing, in contrast to classical filtration laws, including non-monotonic dependences of the flow rate on depression, an approximation model is constructed in the form of the proposed generalized Rawlins–Shellhardt equation. This model opens up a new approach to forecasting the flow rates of gas wells, improves the efficiency of gas production and contributes to the sustainable development of the energy sector. For example, it greatly simplifies planning of geological and technical measures and optimizes the development of gas fields.

Relevance. The need to study the effect of surface plastic deformation of drill pipes on their technological properties, which will significantly reduce the irrational material and energy costs of drilling wells, as well as optimize the technical and economic indicators of drilling operations.

Aim. To increase the productivity of geological exploration by optimizing the operational characteristics of drill pipes.

Objects. Drilling well, drilling shell, drill string, shot blasting of pipes, surface plastic deformation.

Methods. Specialized test benches have been developed and manufactured for conducting experimental studies; processing of experimental research data was carried out by the graphoanalytic method.

Results. The paper introduces the results of the study of the effect of surface plastic deformation produced by means of shot-impact treatment of the surface of the drill pipe material on their technological properties. The conducted studies shown a significant effect of surface plastic deformation of drill pipes on their technological properties and operational characteristics. In particular, it was found that microcracks and other microdefects can lead to a decrease in the strength and fatigue resistance of the pipe, as well as to a deterioration in its corrosion resistance.

Conclusions. The optimal degree of surface coating of LBTN-54 and SBT-42 drill pipes, which guarantees a significant improvement in their technological properties, is close to 80%. With an optimal degree of surface plastic deformation of the material of LBTN-54 drill pipes the stiffness of their cross-section increases by 1.8 times; torsional stiffness grows by 1.3 times; damping capacity increases by 33%, and the amplitude of free vibrations decreases by an average of 1.9 times; power costs for turning them around their curved axis grow by 15%. At the optimal degree of surface plastic deformation of the SBT-42 drill pipe material the stiffness of their cross-section increases by 1.43 times; torsional stiffness grows by 1.4 times; damping capacity increases by 25%, and the amplitude of free vibrations decreases by an average of 1.75 times; power consumption for turning around its curved axis decreases by 7%. Surface plastic deformation of the LBTN-54 drill pipe material contributes to the expansion of the areas of their operation in the well in the mode of direct precession, which ensures the improvement of technical and economic indicators of drilling in difficult geological conditions.

Relevance. The concept of creating low-tonnage methanol production plants is proposed. They include two main nodes: a synthesis gas production complex by non-catalytic partial oxidation of natural gas with oxygen and a methanol synthesis complex using a direct-flow multi-reactor cascade with the release of condensed methanol after each reactor. The plant can enter a chemical cluster and process methanol into useful products.

Aim. Describe the technology and design the installation, determine its main indicators.

Methods. Design of the plant, mathematical and numerical modeling of chemical and technological processes.

Results and conclusions. The paper describes a new technological process of low-tonnage production for methanols. The main apparatus of the installation is an original small-sized syngas gas generator, which provides: high safety, reliability and maintainability; no need to use a catalyst for partial oxidation and the possibility of carrying out the process at high pressures up to 8.0 MPa, which do not require gas compression during subsequent catalytic synthesis of methanol; transportability and modularity of the installation. The paper introduces the results of numerical simulation of natural gas partial oxidation by oxygen. The authors have determined the rational modes of the process in syngas gas generator. The main parameters of the partial oxidation are: the coefficient of excess oxidizer, which should be in the range of 0.34–0.36, and the supply pressure of the components in the range of 6.0–7.0 MPa. The authors carried out the numerical simulation of the methanol synthesis without correction and with preliminary correction of the syngas composition. The data obtained allowed: calculating the degree of conversion of carbon from carbon oxides to methanol; when using a three-reactor cascade with an optimal composition of the gas mixture, the degree of conversion reaches 95%; estimating the maximum specific capacity of the installation up to 1250 kg/hour of methanol per 1000 m³/hour of natural gas and the maximum capacity of the installation up to 20000 tons of methanol per year.

Relevance. Currently, in the practice of geological exploration, if the adjustments to well direction is required, the continuous action deflectors are mainly used. However, their application is fraught with certain difficulties. The time spent on lifting operations associated with the need to prepare the well for curvature, deflector descent, study of the curvature interval, etc. are significant and unproductive. The formed curvature of the well with intensity values from 1.5 degrees/m, even after working through the interval with special projectiles, leads to the risk of significant column bends and potential emergencies, especially when using a projectile with a removable core receiver, due to the impossibility of its use in wells with a curvature intensity of more than 0.1–0.3 degrees/m. The design features of the deflectors and orienting devices determine the difficulties with the correct setting and reliable fixing of the devices on the face, there are frequent cases of deviation of the curvature set plane from the design one. Taking into account the above, the development of a special technical tool that allows with high accuracy and moderate intensity of curvature making operational adjustments to the direction of wells without lifting the drilling column using the removable core receiver complex is an urgent and demanding task.

Aim. To assess the force effect on the rock-cutting tool during the formation of a new direction of the borehole by a removable deflecting complex; assess the influence of the side armament of the diamond tool on the trajectory of the drilled borehole; justify the optimal location of the armament on the periphery of the diamond rock-cutting tool.

Object. Mechanism of formation of a new well direction during milling its wall.

Methods. Collection, analysis and generalization of information about the operation of continuous action deflectors, analytical studies of force interaction in the bottomhole zone when forming a new direction of wells by milling its wall.

Results. The paper introduces the estimate of the time spent on unproductive technological operations when adjusting the direction of wells using continuous action deflectors and a removable deflecting complex. The authors have described the dependence of the formed deflecting force when using a removable deflecting complex on the physico-mechanical and geometric characteristics of the tool, properties of rocks. The paper introduces the dependence to determine the optimal angle of inclination of diamond-cutting stacks to compensate the disorienting force when milling the well wall with a diamond rock-cutting tool.

Relevance. The phenomenon of urbanization, driven by the socio-economic development requirements in various regions globally, is increasingly contributing to reductions in vegetation cover and intensifying ecological and environmental complexities. As a result, monitoring urban expansion has become indispensable for enhancing efficient urban management and facilitating planning regarding ecological and environmental issues.

Aim. To assess the spatial-temporal variations in vegetation cover in Thai Nguyen City, Vietnam over the past two decades under the impacts of urbanization.

Methods. The spatial-temporal changes in vegetation cover were analyzed using the maximum value composite algorithm integrated into the Google Earth Engine platform. The accuracy assessment of the applied classification method yielded high accuracy levels ranging from 91 to 94%.

Results. For 2001–2023, the urban land area increased by 4024 hectares, with an average annual growth rate of 0.78%, rising from 386 hectares in 2001 to 4.410 hectares in 2023. The findings indicate a slight decrease of approximately 773 hectares in vegetation cover during 2001–2010 but a significant increase of up to 2696 hectares during 2010–2023. These findings highlight the potential risks associated with increasing urban land areas within the study area and emphasize the urgent need for appropriate measures to address this issue.

Relevance. The surfaced section of a gas pipeline, ballasted with weights, in a swamp qualifies as «damaged» and must be decommissioned.

Aim. To establish the effect of the weight of weighting agents on a gas pipeline ascent in a swamp. The weight depends on the concentration of moles soluble in water, changes in the values of the physico-mechanical characteristics of the soil due to its watering, and the parameters of the gas pipeline operation.

Objects. Sections of a gas pipeline, ballasted with weights, in a swamp in a watered area.

Methods. Modeling the stress-strain state of a gas pipeline, ballasted with weighting agents, in a swamp by a one-dimensional rod system consisting of rods and their coupling nodes; integration by the Godunov orthogonal run method of a normal system of nonlinear ordinary differential equations describing the stress-strain state of the rods and compiling a solution of systems of algebraic equilibrium equations in the coupling nodes, taking into account the impact of weighting agents on stress-strain state.

Results. The paper introduces the brief information on the surfacing of gas pipelines with weights installed on them. The authors have set and solved the problem of the stress-strain state of the section of the gas pipeline consisting of the middle underwater part, ballasted with reinforced concrete weights, and the extreme flooded underground parts. The analysis of the stress-strain state of the gas pipeline established the following main reasons for its ascent: uneven unequal sedimentation of the base soil on the extreme parts, in which the pipe remains in a trench filled with soil; reducing the weight of weighting agents in water due to an increase in the specific gravity of water due to the growth of concentration of moles dissolved in water. The authors found the critical values of the operating parameters, at which the bulging of the pipe with an upward deflection arrow begins, preceding the ascent of the gas pipeline.

Relevance. Ventilation and air conditioning systems of oil and gas stations contain electromechanical devices, which operation is accompanied by industrial noise and vibration. This has a negative impact on the wear of the equipment itself and on the health of the operators in the room, as the presence of noise is a harmful production factor. In this regard, reducing the vibration and acoustic activity of electromechanical devices is an urgent scientific and technical task that has attracted the attention of developers for many years. It is known that aluminum, as a structural material, combines high rigidity, strength, and the ability to dissipate energy within its volume, making its application for creating solid-state vibration dampers relevant. This work is devoted to studying the damping properties of aluminum and assessing its potential use as a vibration dampener in damping devices for electromechanical devices in life support systems of oil and gas stations. To achieve this, the authors have carried out the experimental studies of samples made from cast and foamed aluminum alloy D16 using an impact stand.

Object. Samples of cast and foamed aluminum alloy D16.

Aim. Experimental studies of the damping properties of cast and foamed aluminum alloy D16 to assess the possibility of its use as a damping element in the oscillators of electromechanical devices within the life support systems of oil and gas stations.

Methods. Modern approaches to vibration diagnostics, computational mathematics, and measuring instruments.

Results. Foamed samples, compared to the cast ones, have greater potential to dissipate the energy of disturbing vibrations from the activity of an electromechanical device and can be used as a damping element.

Relevance. Current trends in processing heavy oil with high sulfur content and tightening environmental fuel requirements necessitate hydrocarbon feedstock purification from harmful components such as sulfur. One of the processes for upgrading medium and heavy oil fractions is hydrotreating. Due to the high importance of the hydrotreating in modern oil refining, the use of mathematical models is critically important in the design of new units, optimization of existing ones, and development of catalysts.

Aim. This work is devoted to forecasting the operation of an industrial vacuum gas oil hydrotreating unit with a change in the composition of the feedstock and the main control parameters using a mathematical model.

Methods. Liquid adsorption chromatography method using the Gradient M unit to determine the composition of vacuum gas oil, gas-liquid chromatography method using the Crystal 2000 M chromatograph to determine the content of sulfur-containing compounds in vacuum gas oil, cryoscopy method in benzene to determine the molecular weight, energy-dispersive X-ray fluorescence spectrometry method to determine total sulfur in vacuum gas oil, pycnometer method for measuring density, quantum chemical research method implemented in the Gaussian program for determining the thermodynamic characteristics of reactions, method of mathematical modeling of chemical-engineering processes

Results. The authors have proposed a 12-component mathematical model of the vacuum distillate hydrotreating. The model takes into account most of the reactions of hydrogenolysis, hydrogenation and hydrocracking of heteroorganic compounds, gas–liquid and liquid–solid mass transfer, as well as the effect of catalyst deactivation with coke on its activity. Based on the results of calculations performed using the mathematical model, it can be concluded that the model of the vacuum gas oil hydrotreating reliably reproduces the dependence of the residual sulfur content in the product on changes in the main control parameters of the industrial vacuum distillate hydrotreating unit.

The authors have studied the decomposition of monazite concentrate by alkali. They investigated the necessary decomposition conditions such as temperature, time, particle size and the ratio between alkali and monazite concentrate by mass (wt/wt). The decomposition is best performed at >140°C, within 8 hours, the required alkali and monazite concentrate ratio was 1,4/1, the ore particle size needs to be smaller than 48 $\mu m$. The decomposition efficiency was also only about 70%. If the desired recovery efficiency was higher than 90%, the alkali/concentrate ratio by mass needed to be at least 4/1, resulting in a large amount of residual alkali. To improve this process, the authors studied the decomposition of monazite concentrate by alkali under pressure. The monazite was taken from Ham Tan deposit. The effecting parameters such as temperature, time, ratio between NaOH/concentrate by mass and particle size of the concentrate were investigated. The results showed that, under the effect of pressure, decomposition occurs faster, more thoroughly and decomposition efficiency increases. The suitable temperature for concentrate decomposition was from 180 to 210°C, corresponding to a pressure of 4 to 7 at. The decomposition time was also reduced to 2 hours and the particle size of the concentrate was also larger to 55 $\mu m$ with 70% alkali and ratio of alkali/concentrate was 1/1. The decomposition efficiency of rare earth elements reached 95%, while under the same conditions, U was 50% and Th was 77%. When the reaction time increased, the efficiency of rare earth elements decomposition did not change much, but the decomposition efficiency of radioactive elements tended to increase. For particle sizes >55 $\mu m$, the process efficiency decreased sharply, and changes in reaction conditions were needed to increase the decomposition efficiency.