The instability of an open wellbore during directional and horizontal drilling is a critical issue that can lead to emergencies and significant economic losses. One of the key methods to prevent wellbore collapse is the careful selection of drilling fluid density based on geomechanical modeling. The objective of this study is a comparative analysis of the influence of the most commonly used failure criteria (Coulomb-Mohr, Drucker-Prager, HoekBrown, Mohr-Coulomb, and Lade) on the calculation of drilling fluid density required to ensure wellbore stability. The work involves one-dimensional geomechanical modeling using the RN-SIGMA 2.0 software package with logging data (density, interval transit times of longitudinal and transverse waves) from five wells obtained from open sources. We calculated profiles of geostatic and pore pressures, dynamic and static elastic properties (Young’s modulus and Poisson’s ratio), strength properties (uniaxial compressive and tensile strength limits, internal friction angle), as well as horizontal stresses according to a poroelastic model. The results showed that the choice of failure criterion significantly affects the required drilling fluid density to prevent wellbore collapse. The lowest density values were obtained using the Lade criterion, while the highest values corresponded to the HoekBrown and Drucker-Prager criteria. The classical linear Coulomb-Mohr criterion yielded intermediate density values. These differences are due to different mathematical formulations of the criteria and their consideration of various rock failure mechanisms. The findings indicate the necessity of carefully selecting a failure criterion appropriate for the lithology and mechanical properties of specific rock intervals.

The article presents the results of the study of geological and hydrogeological The article presents the results of the study of geological and hydrogeological conditions of the south-eastern outskirts of Almetyevsk, Republic of Tatarstan, confined to the III floodplain terrace of the Stepnoy Zay River valley. The main objective is to establish the causes of flooding of the territory and assess the hydrogeological conditions of the studied area, to make design decisions on engineering protection of the territory from flooding and underflooding. It was established that flooding of the territory occurs due to the inflow of water from water-saturated sandy loam, the formation of local pressure and vertical flows, as well as infiltration of atmospheric precipitation. Zoning of the territory was carried out and areas with moderate and slight flooding were identified. As a result of forecast expert calculations, it was possible to establish that the possible maximum increase in the groundwater level will be no more than 12 cm. The maximum possible rise in the groundwater level in the study area would be in its northwestern part reaching 129.42 m, with the depth of the level at 1.00 m, and the pressure value at 2.1 m. The minimum position of the groundwater level in the winter low-water period in the study area would not be below the absolute mark of 125 m, the depth of occurrence is ≈ 5.5 m. The calculation of the volume of water inflow within the study site showed that during the flood the water inflow would be about 5.0 m³ / day, and during the low-water period – about 3.6 m³ / day. The obtained results are of great practical importance for the development of measures for engineering protection of the territory from flooding in accordance with current regulatory and legal acts, design of water drainage systems, design of water drainage systems, rational use of groundwater, and planning of construction activities.

This paper focuses on building a digital model that reflects the variability of the physical and mechanical properties of the Elginskoye deposit. The initial data came from electronic databases compiled from geological and operational exploration reports. The Orange software package was used to create a geological model of the coal-bearing rock mass of the Elginskoye deposit. Block 3D models of the variability of physical and mechanical properties such as compressive strength, tensile strength, and density of carbon-bearing rocks in stratigraphic intervals at depths U6–U5, U5–U4, U4–H16, and H16–H15 were constructed. Modern computer technologies are able to visualize the values of physical and mechanical properties corresponding to each point of a twodimensional cross-section of a geological body. Rather than constructing a complete three-dimensional digital model to assess the structure and condition of the rock mass, an approximation can be constructed using twodimensional cross-sections, which clearly and informatively display the spatial variability of one of the physical and mechanical properties. An example is given of hypsometric plans for the distribution of rock strength under tension, compression, and bulk density at the depth of the surrounding rocks, in the interlayers U6–U5. Interlayer strength was measured at intervals ranging from 0.4 m to 1 m in depth, thereby identifying changes in the physical and mechanical properties of the rock both with depth and laterally. The presented plans demonstrate a significant variability in the strength and density properties of the rock. The strength limit of rocks under uniaxial compression, within the studied intervals, varies from 20.5 MPa to 129.9 MPa, the strength limit under uniaxial tension, from 2.64 MPa to 11.3 MPa, and the bulk density varies from 2.45 g/cm³ to 2.81 g/cm³ . The results of the research can be used to design and plan the development of the deposit, as well as to draw up specifications for drilling and blasting operations, taking into account the variability of the properties of carbon-bearing rocks.

The article considers the problems and ways of efficient utilization of associated petroleum gas. The geological causes of excess production of associated petroleum gas at the developed fields of the Nepa-Botuobinskaya anteclise in the southwest of the Republic of Sakha (Yakutia) are designated. The inexpediency of utilizing associated petroleum gas by generating electricity is noted due to the excess of the latter in the region. The infrastructural, technological and fiscal factors contributing to the flaring of associated petroleum gas are listed. Based on the territorial location of the developed fields, the Talakanskaya, Botuobinskaya and Mirninskaya oil production locations are identified. The reserves of dissolved gas and gas cap gas for the developed oil fields are presented as a percentage of the total reserves of the developed fields. It is concluded that the Botuobinskaya oil production location with excess production of associated petroleum gas is the one with the best gas reserves. For the efficient utilization of associated petroleum gas, it is proposed to organize a large gas (energy) consumer in the form of data processing centers (DPC) with fiber-optic communication lines (FOCL) to Northern China on the territory of the Botuobinskaya oil production location. Aggregated calculations show a favorable difference (more than 50 times) in the cost of laying a FOCL line relative to the construction of a gas pipeline with a similar length. It is concluded that the remoteness of the territory, the availability of a cheap energy source and a free cold climate will determine the advantage in all the main processes of energy consumption of the DPC. To level out the costs associated with construction in hard-to-reach areas, it is proposed to apply tax breaks to construction projects for the utilization of associated petroleum gas.

Currently, the problem of reducing the efficiency of reservoir pressure maintenance systems at late stages of field development with highly heterogeneous reservoirs is a serious one for the oil and gas industry. This paper considers the Srednebotuobinskoye oil and gas condensate field (SBNGKM), which is characterized by highly heterogeneous reservoir, water cut in some wells exceeding 95%, and low water injection efficiency. In this paper, waterflooding optimization using the streamline method was applied for the first time for the conditions of one of the largest fields in Yakutia – SBNGKM. The objective of the work was to increase the efficiency of reservoir pressure maintenance by redistributing injection between injection wells using hydrodynamic modeling of streamlines. The research materials included a three-dimensional hydrodynamic model of the Bt formation of the SBNGKM central block in the tNavigator software, historical data on 37 production and 15 injection wells for the period 2010-2021. An algorithm for redistributing injection with an increase in volumes in highly efficient wells by 20-30% and a decrease in low-efficiency wells by 15–40% was implemented. The results showed an increase in average injection efficiency by 41%, a decrease in water cut by 3.2% and an increase in cumulative oil production by 65,414 tons over a 10-year forecast period. Practical significance is confirmed by an increased ultimate oil recovery factor by 1.7% without capital expenditures. The prospects of the study are associated with the development of adaptive algorithms for automatic optimization based on machine learning and the integration of real monitoring systems for filtration parameters. The implementation of the proposed methodology can significantly increase the economic efficiency of developing complex reservoirs at a late stage of operation due to the rational use of the existing well infrastructure and water resources.

In recent years, forest fires have demonstrated an increasing trend in Yakutia, associated with modern global warming and extensive activation of cryogenic processes. In Central Yakutia, an ice complex is widespread, confined to the inter-alas type of terrain. Thawing of the ice component of the soils leads to the development of thermokarst, which is observed in disturbed treeless areas. The general climatic conditions, lithological and geocryological characteristics of the areas for which numerical modeling of the thermal state of soils was performed are described. The thermal state of inter-alas soils in 8 areas after forest fires was modeled during vegetation restoration, taking into account the current trend of increasing air temperature by 0.02о /year. The models were compiled for key periods of change in surface conditions and vegetation: 3, 8, 10 and 25 years after forest fires. It was revealed that in the Pokrovsk, Borogontsy and Berdigestyakh areas, it is possible to reach the depth of thawing of the ice horizon, which is due to high mean annual air temperatures and the spread of sandy loam in the upper part of deposits. And if the vegetation is not restored within the first three years, then presumably cryogenic processes will occur in these areas. In other areas, according to the modeling results, thawing does not reach the ice complex; gradual self-restoration of vegetation should bring geocryological conditions to their original state within 20-25 years. Soil temperatures are expected to rise, which is related to the current general warming of the climate. If the warming trend continues, thawing and soil temperature increases will be more significant and noticeable.

Currently, about 45% of the population of the Republic of Sakha (Yakutia) lives in the valley of the middle reaches of the Lena River. The effects of climate change to varying degrees can have both negative and positive impacts on the lives of these people. The purpose of this article: to identify the features of changes in air temperature and precipitation regime in the study area. The paper uses methods of statistical analysis and scientific generalization. Meteorological series of three stations located in the valley of the middle reaches of the Lena River – Namtsy, Yakutsk and Pokrovsk – were analyzed. The air temperature is taken for the period 1961-2024, which covers the old base period 1961-1990 and the current climatic norm 1991-2020. The series of atmospheric precipitation were analyzed for the period 1966-2024. To simplify the task, the period from May to September was taken for the warm period, and the period from October to April for the cold period. Statistically significant trends in annual air temperature were revealed, the rate of change in Pokrovsk is 0.4 ° C/10 years, in Yakutsk and Namtsy 0.6 ° C/10 years. The sums of the daily temperatures of the warm period increased significantly. Analysis of precipitation did not find statistically significant trends; graphical visualization of their dynamics provides insight into significant year-to-year variability. At all stations since 2014, there has been a decrease in the amount of precipitation of the warm period, and in the last 5 years – an increase in the amount of precipitation of the cold period. The results obtained can be used when adopting plans for regional adaptation measures in the Republic of Sakha (Yakutia), in particular, for its central, most populated part.