The purpose of the article is to present the results of comprehensive express petrophysical core studies conducted at one of the wells of the Tas-Yuryakh oil and gas condensate field. The research covers three productive horizons: Є₁blᵒ⁻ˡˡ (Osinsky), Vbk₁ᵇᵗ (Botuobinsky), and Vcrᵗˡ (Talakhsky). The study obtains and analyzes a dataset including the measurements of effective porosity, absolute permeability, residual water and hydrocarbon saturation and carbonate content. As a result, fundamental differences in the reservoir properties of the studied horizons have been established, determined by their lithology and type of void space. The Botuobinsky horizon is characterized as a high-quality terrigenous reservoir with record permeability values of up to 837.1 mD and porosity of up to 27.5%. For the Osinsky horizon composed of carbonate rocks a diagnostic paradox has been revealed between the extremely low matrix permeability (0.42 mD) and clear signs of hydrocarbon saturation that indicates a fractured reservoir type. The Talakhsky horizon, despite the signs of residual bituminization, features isolated void space and low reservoir properties (permeability is around 3.5 mD), which excludes its commercial value in the studied area. The study focuses on the detailed analysis of the porosity-permeability relationship, which becomes a key tool for differentiating reservoirs by the genetic type of void space and their potential assessment. The research results are of significant practical importance for building a reliable geological model of the field and designing an effective development system.

There are various methods of supporting underground mine workings, each of these methods has a number of advantages and disadvantages. The most versatile method has proven to be the support that includes a concrete mixture (shotcrete and gunite – concrete support, reinforced concrete support, etc.). Today, many mines and mining operations use concrete mixtures to construct various structures in the conditions of underground mining, while mining enterprises often face the problem of concrete losing its strength characteristics during operation. The purpose of the study is to provide the most accurate assessment of concrete behavior under various aggressive environmental factors, such as thawing of the rock mass and the presence of aggressive waters at the support installation site. The paper also discusses possible methods for increasing strength and resistance to various destructive factors. The research included testing concrete for frost resistance, conducting electrolysis tests, adding various components to increase the strength of concrete samples, as well as comparing different concrete grades. The obtained results allowed to provide a more accurate assessment of the influence of negative factors on the physical and mechanical properties of concrete support, as well as to select an integrated approach to increasing the stability of support under various conditions of underground environment.

This work is devoted to the study and comparative analysis of the effectiveness of geochemical methods for predicting oil and gas potential in the Arctic regions of Western and Eastern Siberia. The features of geological conditions influencing the selection and implementation of exploration methods are considered. The analysis is given to the historical experience of developing oil and gas resources in the region, starting from the Soviet period and highlighting the achievements of renowned scientists such as V.P. Isaev and others. The work thoroughly examines the theoretical foundations of geochemical prediction including the theory of subvertical hydrocarbon migration and the identification principles of geochemical anomalies. The main geochemical research methods applied in Western and Eastern Siberia are described. Special attention is paid to an integrated approach combining geochemical, geophysical, and geological data. The article provides some examples of successful application of geochemical methods such as identification of promising oil and gas zones in the South-Syuldyukar area and confirming significant resources at the Medvezhye field. Recommendations are given for improving forecasting methods, including the creation of a unified database, automation of data processing, and introduction of new remote sensing technologies. The necessity of international cooperation and interaction between scientific organizations and industrial enterprises to accelerate the adoption of advanced technologies and ensure the sustainable development of Russia’s oil and gas industry is emphasized.

The paper considers Multilateral Stimulation Technology, a wellbore stimulation technology designed to enhance oil recovery in carbonate reservoirs with low vertical permeability and low effective oil pay. The purpose of the study is to analyze Multilateral Stimulation Technology efficiency in reservoirs with oil rims thinner than 5 m in highly heterogeneous and fractured rock conditions. The object of research is horizontal and directional wells equipped with radial formation drilling system using retractable needles. The subject of the study is technological features of Multilateral Stimulation Technology application including modifications involving acidizing of the rock ahead of the nozzle and mechanical drilling with turbine-driven mini-bits. The research methods include field data analysis, a review of international and domestic experience, interpretation of field results, as well as a comparative assessment with traditional hydraulic fracturing. The mechanisms of radial laterals formation, the influence of geological factors on technology efficiency, and filtration process modeling features are examined. The study results demonstrate that Multilateral Stimulation Technology provides a controlled increase in reservoir drainage volume, reduces the risk of water and gas breakthrough, and increases well productivity by 2–4 times compared to untreated wells. Acid activation and turbine drilling significantly increase the penetration depth and stability of lateral channels. The technology was found to be most effective in carbonate reservoirs with permeability of 0.1–10 mD and a low Kv/Kh ratio. It is concluded that Multilateral Stimulation Technology represents a promising alternative for developing thin oil rims and hard-to-recover reserves in the Russian Federation, offering a controlled substitute for conventional hydraulic fracturing.

The Bolshetagninskoye deposit is one of the largest known endogenous deposits,which is promising for niobium ore development. It is confined to the Ziminsky complex of ultramafic alkaline ultramafic alkaline rocks and carbonatites of Late Riphean age. The purpose of the study is to identify the distribution patterns of niobium in rocks and ores of the Bolshetagninskoye alkaline-ultramafic carbonatite massif at different stages of endogenic and postmagmatic processes using the methods of optical microscopy, scanning electron microscopy, X-ray diffraction electron microprobe analysis (microprobe), and X-ray fluorescence analysis. It has been determined that the primary niobium ores belong to holocrystalline apatite-mica and apatite-pyrochlore rocks. The main minerals concentrating niobium in these ores are fluorocalciumpyrochlore and ferrocolumbite. It is noted that a close paragenesis of apatite and pyrochlore has been observed. The remaining (secondary) ore types are associated with pyrochlore alteration products from primary ores and formed as a result of the redeposition of niobium in new geochemical conditions. Secondary niobium ores are represented by calcite carbonatites, potassium feldspar, and other metasomatites. The main minerals in these rocks with superimposed niobium mineralization – niobium concentrators – are presented by niobium-bearing rutile, ilmenorutile, niobium-bearing hematite, newly formed fluorocalciopyrochlore and ferrocolumbite. Among the studied rocks pyrochlore is represented by fluorocalciopyrochlore and uraniumpyrochlore, significantly enriched in tantalum. Unaltered fluorocalciopyrochlores from apatitite-pyrochlore, apatite-mica, and calcite-feldspar rocks are characterized by a consistent composition of CaO, Na₂O, and SrO. Altered, hydrated varieties (based on the A-site vacancy) are more characteristic of metasomatic rocks and calcite carbonatites with superimposed pyrochlore mineralization. This reflects varying degrees of fluid processing of these pyrochlores. The conducted study revealed that the niobium ores of the massif underwent a multiphase, multistage transformation, which is represented by a decrease in the ore component content and the presence of different oxide forms of niobium in secondary ores compared to primary ores.

The purpose of the conducted study was to identify the spatial and temporal distribution of heavy metals and arsenic in a gas condensate field for the period from 2019 to 2025. The annual increase in manganese, arsenic, and nickel concentrations exceeding the estimated permissible concentrations allowed for a clear assessment of the relationship between the intensity of development in the gas production zone and the level of negative impacts from the release of these elements into the soil. In accordance with the objectives, a critical analysis of all production units on the industrial site was conducted to assess the potential for pollutants to enter the soil. The coefficients of element accumulation were obtained relative to the global clarks according to Vinogradov. Thus, arsenic, manganese, and nickel showed an increased accumulation coefficient of Kk ≥ 1.5. Geoecological processes associated with technogenesis in the area of the gas condensate field are accompanied by the formation of soil contamination halos, which was determined using geoinformation system technologies. Geochemical parameters of soils, as indicators of their conditions, reflect high functionality under the adverse impacts of gas production and provide a realistic assessment of the geoecological situation at the field. It is shown that the spatial distribution of manganese and nickel elements is primarily related to technological processes, regular production works and welding. The excessed contents of arsenic may be due to the inherited geological and geochemical features of the Baikal natural territory with the elevated content of this metalloid in the soil imported for the Kovykta gas condensate field development. Thus, the integration of geoinformation system technologies and geochemical survey results is an effective tool for the comprehensive geoecological assessment of the territory in the technogenic zone and serves as a basis for the development of effective, modern, object-oriented monitoring in the gas condensate field zone.

The purpose of this work is to improve the safety and cost-effectiveness of the counter-cementing process of casing strings under conditions of lost circulation and the risk of gas, oil, and water shows, using the Yurubcheno-Tokhomskoye field as an example. The causes of frequent failures of the universal preventer during the counter-cementing with the closed universal preventer in order to create a vacuum effect were analysed. The study was given to the geological and technical conditions of the Yurubcheno-Tokhomskoye field, which led to 28 cases of equipment failure in 2023–2024. The design and operation principle of the sub-preventer sealer as an alternative technological solution were considered. A comparative technical and economic assessment of the sealer implementation was performed and the discounted cash flow, payback period, and profitability index were calculated. It was determined that the main cause of universal preventer failures was due to the operation of the sealing element in an aggressive cement slurry environment under the influence of a vacuum. It led to the loss of the second safety barrier. The proposed solution (to install a sub-preventer sealer between the casing head flange and the blowout preventer crosspiece) allows to seal the annular space of the casing string without the use of a universal preventer. The feasibility study showed that a one-time investment of 16 million rubles for equipping 5 drilling rigs covers the expenses during the first year of operation providing significant annual savings by eliminating the repair cost of the drilling rigs. The introduction of a sub-preventer sealer makes it possible to eliminate a major technological risk of second barrier failure during counter-cementing, thereby increasing the industrial safety of work. The technical solution is economically feasible since its yield index is <1 and its discounted payback period is less than a year. It can be recommended for use in fields with similar complex mining and geological conditions.

Remote sensing methods enable the rapid study of large, hard-to-reach areas prone to hazardous gravitational geological processes (landslides, rockfalls). Regional mapping of high-risk landslide areas based on satellite remote sensing data is already well-developed. In recent decades, the theory and practice of using unmanned aerial vehicle (UAV) technologies for remote sensing have rapidly evolved. In both cases, multispectral survey data and digital elevation models are used to analyze geological risks. The purpose of the presented research is to compare the results of landslide susceptibility mapping based on available satellite data and unmanned aerial vehicles data and to identify the advantages and limitations of both methods. The key predictors for satellite data (slope angles, profile curvature, normalized difference vegetation index, wetness index and length-slope factor) were derived from ALOS AW3D30 digital evaluation models and Sentinel-2 data. Unmanned aerial vehicle data were obtained using a photogrammetric method with multispectral cameras. To determine the weights of factors, the analytical hierarchy process was used through pairwise comparisons. Landslide susceptibility maps were generated for the same area using QGIS. The comparative analysis has clearly demonstrated how differences in input data resolution and survey methodology impact the predictive value of the results. The major finding is that due to resolution generalization (in the case of satellite imagery) small, unstable rock blocks can artificially increase the vulnerability of adjacent slopes, on the other hand, some small, but hazardous rocks can remain completely unnoticed. At the same time, it is shown that high-resolution data from unmanned aerial vehicles do not replace satellite remote sensing data, but rather complement it. The methods serve different spatial scales and research objectives. The results confirm that satellite data and data from unmanned aerial vehicles should be complementary. Satellite data are suitable for regional landslide susceptibility mapping, while data from unmanned aerial vehicles are essential for detailed studies of individual areas identified using satellite data. Therefore, a hybrid methodology is recommended: satellite data for the initial zoning of hazardous areas, and data from unmanned aerial vehicles for the detailed study of hazardous areas.