This study presents the identification and classification of eight distinct petrophysical rock types in the GCA-1 well of the Chirag field using a comprehensive petrophysical integration workflow. The Petrophysical Integration Process Model (PIPM) was applied through two independent yet complementary approaches: (1) the Winland method, supported by capillary pressure data for pore throat radius characterization, and (2) a statistical clustering methodology, including elements from Heubeck and other prior works. Both approaches yielded consistent rock type classifications and leveraged permeability as the primary distinguishing parameter, given its variation across five orders of magnitude and its dominant control on fluid flow behavior. Pittman’s R20 methodology, which defines the pore throat radius at the 20th percentile mercury saturation, demonstrated the strongest correlation between pore throat size and permeability, making it the most effective tool for rock typing in this dataset. A reasonably strong correlation between porosity and permeability was also observed, providing additional confidence in the classification results. The identified rock types show a general correspondence with depositional lithofacies as defined by Reynolds and Nummedal; however, rock types often transcend individual lithofacies boundaries. This emphasizes the need for integrated petrophysical approaches that go beyond sedimentological classification alone. The integration of multiple datasets and methodologies provides a robust foundation for reservoir characterization and flow unit delineation within a geologically complex and tectonically active setting. The workflow and findings from this study deliver valuable insights for field development planning, reservoir modeling, and future petrophysical evaluations in similar depositional systems.

Keywords: Vychegda Trough; Domanic Formation; hydrocarbon potential; basin modeling; source rock; generation potential.

Date submitted: 17.12.25    Date accepted: 14.03.26

References

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The Vychegda Trough is one of the least studied structures in the northern part of the Volga-Ural Basin. In the meantime, the presence of Domanic Formation deposits with possessing geological and geochemical characteristics of source rocks in the Vychegda Trough area makes this territory promising. In this paper we have collected and summarized the results of studies of sediments of the Domanic Formation in the Vychegda Trough, and conducted lithological and geochemical studies of core material of the Domanic Formation in a well close to the territory under consideration. Kinetic spectra of kerogen degradation were obtained, basin analysis was performed, which allowed to study the spatial and temporal regularities of development of the hydrocarbon source kitchen, realization of the hydrocarbon potential, as well as to reveal modern catagenetic zonality of the Domanic Formation of the Vychegda Trough. It was established that the hydrocarbon potential of the Domanic Formation of the Vychegda Trough was formed in the time interval from the Early to the Late Triassic inclusive, and the main the hydrocarbon source kitchen developed within the boundaries of submerged areas, confined mainly to the northeastern and southeastern parts of the object under study. The paper also evaluates the prospects of hydrocarbon potential of the Domanic Formation in terms of generation possibilities.

Keywords: Vychegda Trough; Domanic Formation; hydrocarbon potential; basin modeling; source rock; generation potential.

Date submitted: 17.07.25    Date accepted: 14.01.26

References

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This study presents the results of an integrated study of the petrophysical and lithological properties of Jurassic and Triassic rocks in the Morskoye field and the Ogayskoye block, within the Caspian Basin. The research aims to refine reservoir evaluation parameters through detailed laboratory analyses of core samples with geophysical well log interpretation. Core material from 23 wells (1980 samples) was analyzed using mineralogical, granulometric, and petrophysical methods, with additional verification from seismic data and well test results. Mineralogical studies based on X-ray diffraction confirmed the predominance of quartz, carbonates, and clay minerals, while granulometric analysis revealed the dominance of fine-grained and pelitic fractions, explaining the generally low filtration capacity of the studied reservoirs. The laboratory experiments established robust empirical relationships between porosity, permeability, and saturation parameters. Strong statistical reliability was achieved, particularly for the K₁al–K₁nc stratigraphic intervals, where reservoir properties demonstrated stability and consistency. A clear linear correlation between bulk density and porosity was identified, allowing accurate determination of the matrix density (2.69 g/cm³) used in quantitative well log interpretation. Special attention was given to the recognition of thin coal interbeds within Jurassic deposits. These intervals showed distinctive geophysical responses, including abnormally high neutron porosity and low bulk density, and were systematically excluded from reservoir classification to avoid misinterpretation. Phase permeability tests demonstrated the significant influence of residual oil and water saturations on multiphase flow behavior, offering insights into displacement efficiency and fluid mobility within pore networks. The study also determined lithology- and depth-specific threshold values of porosity and permeability, which enhance the accuracy of identifying and delineating productive intervals. The results provide a reliable methodological foundation for improving reservoir characterization, refining hydrocarbon reserve estimation, and supporting exploration and development strategies in geologically complex settings.

Keywords: reservoir; filtration; saturation; core; porosity; permeability.

Date submitted: 15.05.25    Date accepted: 28.10.25

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Carbonate minerals within clastic sedimentary rocks exert a strong influence on reservoir storage capacity and fluid flow. The carbonate minerals form in two ways: 1) primary, via biogenic precipitation during the depositional phase; 2) secondary, via diagenetic processes. The primary carbonate cements generally preserve porosity uniformly, producing only minor effects on reservoir quality. The secondary carbonate cements influenced by fluid-rock interactions can drastically reduce reservoir properties. For example, pore-filling calcites are notorious for reducing porosity and permeability by effectively infilling pore spaces and isolating the interconnected pore network. The extent to which carbonate cement degrades the rock properties directly correlates with its concentration. Low contents exert minimal impact, whereas higher concentrations promote pore isolation. The carbonated sandstones can exhibit an inverse relationship between porosity and permeability. For example, the development of fractures can locally alter permeability, sometimes decoupling it from the primary porosity framework. This study integrates core data from Masazyr, Binagady, and Garadagh fields to assess carbonate controls on Oligocene–Miocene reservoir quality. Spontaneous Potential (SP) logs from Umbaki were used for shale volume (VSH) estimates to characterise sedimentary trends in Maykop III; coarsening-upward and fining-upward sequences defined depositional architecture. Carbonate content >35% reduces reservoir quality according to the results. Optimal targets as good reservoirs are sand-silt layers with low clay and carbonate (<20%) and high permeability (up to 12.4 × 10^–15 m²). High-porosity, low-permeability siltstones may also serve as a good reservoir. Despite weak carbonate-porosity-permeability trends, the results refine facies and reservoir models, improving quality prediction in carbonate-affected clastic systems.

Keywords: petrophysics; permeability; porosity; carbonate content; Miocene; Oligocene.

Date submitted: 14.02.25    Date accepted: 15.10.2025

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The Pakistan-Iran border region remains underexplored despite its strategic location within the hydrocarbon-rich Middle East. The Middle East holds 50% of proven oil reserves and 40% of world’s natural gas reserves in the world. There have been several myths of shared petroleum system between the two countries, without proper geological evidence. However, there has never been a comprehensive discussion of the geological setting and framework. Recently, there has been interest of several oil and gas companies in Pakistan to explore the Makran-Kharan area. This review investigates the geological characteristics and petroleum systems of the transboundary basins between Pakistan and Iran. The study synthesizes existing geological, geophysical, and geochemical data to assess hydrocarbon potential, highlighting key elements such as sedimentary basins, source rocks, reservoir formations, and trapping mechanisms. Although significant petroleum reserves are concentrated in western Iran, the southeastern region near the Pakistan border exhibits minimal exploration and discoveries. Key basins, include the Makran Offshore Basin, Kharan Forearc Basin, and Jaz Murian-Mashkel Forearc Basin. Furthermore, these basins show promising indicators such as oil seeps, structural traps, and seismic anomalies. This paper calls for increased collaboration between Pakistan and Iran, enhanced exploration efforts, and further geophysical surveys to unlock potential reserves. This will not only boast exploration efforts in Eastern Iran and Western Pakistan but also bring a positive changes in their economies. This study will be a landmark in understanding the sedimentary basins of the Middle East, South Asia, Southwest Asia, and the Caspian Sea region.

Keywords: proven oil reserves; gas reserves; geophysical and geochemical data; Makran-Kharan area; sedimentary basin.

Date submitted: 16.05.2025    Date accepted: 17.11.2025

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This work is focused on improving reserve development efficiency and increasing the oil recovery factor (ORF) at mature oil fields producing high-viscosity crude oil. This issue is of particular relevant for the Republic of Kazakhstan, where high-viscosity oil reserves exceed 900 million tons and are largely confined to long-developed fields with declining production performance. In such conditions, conventional chemical or thermal stimulation methods often fail to deliver sustainable results, necessitating the application of technological solutions. The study analyzes combined enhanced oil recovery approaches, with emphasis on thermal gas-chemical treatments based on the interaction of aluminum-based alloys with formation water. These reactions generate heat and gaseous products, forming a localized thermobaric effect in the bottomhole zone. As a result, oil viscosity is reduced, fluid mobility is improved, and filtration characteristics in the near-wellbore region are enhanced. The proposed technological concept involves the use of multicomponent alloys as an alternative in-situ energy source for thermochemical treatment. The application of such alloys is aimed at the destruction and removal of asphaltene-resin-paraffin deposits (ARPD), restoration of reservoir permeability, and mitigation of ARPD accumulation in tubing during long-term well operation. The research methodology includes laboratory studies of thermochemical processes occurring in the bottomhole. Implementation of the proposed technical solutions contributes to the development of enhanced oil recovery technologies and provides a basis for improving the efficiency and sustainability of high-viscosity oil production at mature fields.

Keywords: high-viscosity oils; thermal impact; oil recovery factor; water cut; modeling; reservoir pressure; development efficiency.

Date submitted: 30.10.2025    Date accepted: 09.02.2025

References

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The application of modern approaches to the selection of stimulation methods at the initial stage of field development is one of the serious factors influencing process efficiency. Stimulation methods to maintain the development rate and enhanced oil recovery were simulated based on the three-dimensional geological and hydrodynamic models of the productive horizons of the West Absheron field, and the efficiency of these methods was evaluated. On the basis of geological, geophysical, and production data, geological and hydrodynamic field models were developed, initial geological resources were evaluated, and the development history was restored within the hydrodynamic model. Selection of more efficient stimulation methods was investigated on the basis of the hydrodynamic model. The processes of water, polymer solution, hot water and steam injection into the formations were simulated. Following model completion, the optimal placement of new production and injection wells was defined. Field performance was forecast and compared according to various options. Based on a comprehensive analysis of geological, geophysical, and field data, detailed geological and hydrodynamic models of the West Absheron field were developed. Based on the results of analogous studies conducted at similar fields, the dependencies of phase permeabilities of gas-oil and water-oil ratios were developed for the productive horizons of West Absheron field and corrected in the process of restoring the development history. The hydrodynamic model was used to select the optimal formation stimulation method. Development parameters were predicted for six different options and the results were compared.

Keywords: field; horizon; well; development; model; stimulation technique; prediction.

Date submitted: 23.09.2025    Date accepted: 23.02.2026

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At present, most oil-producing countries are developing fields with hard-to-recover oil reserves. To achieve high technological and especially economic indicators, it is necessary to apply methods that influence oil-bearing formations. Enhanced Oil Recovery (EOR) methods are among the most relevant tasks of modern oil production, since they make it possible to increase the oil displacement coefficient in individual zones that were previously unaffected, as well as in the reservoir as a whole. In addition, they help improve the main parameters of oil mobility within the formation. Most physico-chemical methods for increasing oil recovery are based on the properties of oil droplet detachment from the pore surface. These properties include wettability, adhesion, interfacial tension, and capillary pressure. For this purpose, a methodological approach is required to determine an effective chemical agent. This involves conducting laboratory studies of the physicochemical properties of the proposed agent (in our case, an alkaline solution) and, based on these results, determining its optimal concentration. Laboratory studies of the properties of the agent and oil were carried out using the following instruments: a Contact Angle Meter SDC-100, the «Spinning Drop» method (rotating drop), and a stalagmometer for calculating capillary pressure. To verify the reliability of the obtained results, they were tested on a reservoir model. For this purpose, experimental studies of oil displacement from the formation using an alkaline solution with optimal concentration were carried out. The obtained results showed good efficiency of this technology. Moreover, the higher the concentration, the higher the oil displacement coefficient.

Keywords: oil; alkali; contact angle; adhesion; concentration; oil displacement factor.

Date submitted: 01.09.2025    Date accepted: 26.01.2026

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This study explores the use of unsupervised machine learning to optimize operational efficiency and reduce downtime in oil well production through clustering analysis. Using production data from a major Kazakhstani oil operator, the study applies K-means clustering to categorize oil wells based on output patterns. The dataset includes more than three million entries over a two-year period, capturing daily values for oil volume, liquid volume, and water cut percentage. Data preprocessing involved normalization, outlier handling, and correlation analysis to ensure robust clustering performance. The optimal number of clusters (K = 10) was selected using the Elbow method. Cluster interpretations revealed distinct operational profiles, including stable, declining, and volatile well behavior. In particular, more than 70% of wells remained in their assigned clusters over time, suggesting temporal stability and operational consistency. By identifying risk-prone and underperforming wells, the results support proactive maintenance, informed resource allocation, and long-term planning. The study demonstrates how unsupervised learning techniques can support data-driven decision-making in the petroleum industry without reliance on expensive sensor infrastructure. This research provides a replicable framework for oilfield analysis and highlights the value of behavioral clustering as a predictive tool for operational optimization. Our methodology integrates unsupervised learning, dimensionality reduction techniques, and visual analytics to provide interpretable cluster groupings. The enhanced predictive model demonstrates the potential to support data-driven decision-making and resource allocation in oilfield operations.

Keywords: machine learning; K-means clustering; predictive maintenance; oil well monitoring; statistical analysis.

Date submitted: 10.07.2025    Date accepted: 17.11.2025

References

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The continuing depletion of conventional oil fields leads to the need of looking for alternative sources of energy to meet the future demand for hydrocarbons. Since most of oil reserves in the world today are considered unconventional, it is important to understand their behavior in porous media better and to develop efficient methods of their extraction. This is also related to non-Newtonian oil reserves which form a significant part of unconventional reserves in the world today. The purpose of this work is to study the flow of non-Newtonian Herschel-Bulkley fluids in porous media under unsteady-state conditions using numerical simulation. A modified diffusivity equation is derived based on the continuity equation in porous media and the modified Darcy’s law for Herschel-Bulkley fluids. Then the logic of numerical simulation is described which is based on the finite difference method. Two different boundary conditions have been considered – constant flow rate in the wellbore and constant pressure in the wellbore. The numerical method is validated by comparing results with results of exact analytical solutions for simpler fluid models. Subsequently, numerical simulation was performed for the Herschel-Bulkley model for which no analytical solutions exist. The impact of non-Newtonian parameters as power-law index, initial pressure gradient and consistency index on reservoir development indicators such as pressure and oil recovery factor were analyzed. The results indicate that the most influential parameter is the power-law index which strongly affects both oil recovery factor and pressure, while the impact of other parameters is not significant.

Keywords: non-Newtonian fluids; Herschel-Bulkley model; unsteady-state flow in porous media; numerical simulation.

Date submitted: 16.08.2025    Date accepted: 15.01.2026

References

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This study develops an analytical framework for evaluating contact pressure and wear in the plunger–cylinder pair of sucker rod pumps operating under thermoelastic deformation. The motivation arises from the sensitivity of sealing performance to clearance growth, where leakage increases approximately with the cube of the gap, making wear control crucial for long-term pump efficiency. Several existing plunger concepts are reviewed, with emphasis on the adverse role of mechanical impurities (mainly sand) that degrade sealing and intensify hydroabrasive wear. To mitigate this effect, a modified plunger design is proposed in which the end heads contain variable-diameter annular projections. These elements promote rapid fragmentation of abrasive particles in the entrance zones of the pair, reducing the probability of damaging contact and facilitating the passage of fine particles through the clearance. The contact problem is formulated by incorporating the thermoelastic radial displacements of both the plunger and the barrel into the primary compatibility condition. The unknown contact pressure is expanded into trigonometric series and determined through algebraization, with reduced linear systems solved numerically. Using the obtained pressure field, the temperature distribution in the contact region and the radial (linear) wear function ℎ(θ, t) are calculated for different plunger velocities and surface roughness conditions. The results demonstrate pronounced non-uniformity at low contact pressures and a trend toward more uniform wear as contact intensifies. The proposed structural solution and the developed calculations provide practical guidance for improving the durability and operational efficiency of sucker rod pumps.

Keywords: sucker rod pump; thermoelastic deformation; plunger-cylinder pair; contact pressure; hydroabrasive wear.

Date submitted: 01.09.2025    Date accepted: 24.02.2026

References

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Reducing carbon dioxide (CO₂) emissions in the oil and gas industry is of strategic importance in terms of ensuring environmental sustainability and combating climate change. In this study, the role of layer resistance in a fixed-layer adsorber was investigated in order to increase the efficiency of CO₂ adsorption. The mathematical model was based on a two-stage mass transfer approach and was developed taking into account the diffusion, flow profile and resistance of the adsorbent layer. The models were solved in MATLAB, and the results were compared with the output concentration in real time. In the experimental part, experiments were carried out in a column with a fixed layer under various conditions of temperature (5-45 °C), flow rate (0.01–0.5 m/s) and co₂ concentration (0.5–2 % vol.), and the adsorption capacity and capture efficiency were calculated. The results showed that the adsorption capacity reached a maximum value of 62.8 mg g⁻¹ at low flow rates and moderate temperatures, whereas at higher flow rates, reduced contact time led to a significant increase in the CO₂ concentration in the exhaust gas. Research shows that taking into account the internal and external resistance in fixed-bed adsorbers makes it possible to accurately model the process and increase efficiency. This approach allows not only to reduce CO₂ emissions by oil and gas companies, but also to optimize their carbon footprint and ensure compliance with international environmental requirements.

Keywords: CO₂ adsorption; ecology; bed resistance; modeling; oil and gas industry.

Date submitted: 20.06.2025    Date accepted: 24.11.2025

References

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This article examines metallurgical defects responsible for uncontrolled and sudden failures of oil and gas pipelines. It is shown that fracture initiation originates from crack nucleation sites retained in the pipe steel microstructure due to deviations from proper metallurgical processing regimes. To verify this assumption, detailed macro - and microstructural analyses of pipe steel were conducted. The results reveal pronounced structural banding, characteristic distributions of sulfide inclusions, and delamination paths associated with crack development within the pipe wall. Within the banded structure oxide inclusions were also identified. Fractographic examination of defective pipe sections using scanning electron microscopy demonstrated that fracture preferentially occurs in regions with high concentrations of non-metallic inclusions. Fracture surface morphology was analyzed in specimens subjected to transverse and vertical impact loading. It was discovered that brittle cracks in vertically loaded specimens form in regions of the base metal lacking plastic deformation and are primarily associated with accumulations of sulfides and oxides. Microcracks within sulfide inclusions act as initiation sites for slip band formation and, under increasing stress, promote ductile crack propagation, while their coalescence along elongated sulfide inclusions accelerates crack growth. Mechanical properties measured in longitudinal and transverse directions coincided with a probability of 0.95. A strong correlation (0.94) was identified between the stress intensity factor (K₁c) and banding length. Fracture toughness tests indicate that steel failure may occur at stress levels below the yield strength in the presence of microscopic pores and non-metallic inclusions.

Keywords: pipelines; oil and gas industry; steel microstructure; non-metallic inclusions; sulfide compounds; banding; crack formation.

Date submitted: 13.05.2025    Date accepted: 22.10.2025

References

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In this study, a multi-step numerical method was suggested for solving the integral constitutive equation for hereditary creep, accounting for the nonlinear characteristics of instantaneous and time-dependent concrete deformations. Numerical verification demonstrates that the method exhibits high computational stability and accuracy, even for relatively large values of time increments in the solution of relaxation problem. By incorporating hereditary creep effects, the long-term loading response of reinforced concrete support structures is practically transferred into a series of incremental short-term static analyses performed at discrete time points. The structural model considers a cantilever circular reinforced concrete member subjected to axial compressive and transverse lateral loads applied at its free end. The proposed computational model enables the determination of the time evolution of the load-carrying capacity and stress–strain state from the initial loading stage to any specific load value. Parametric numerical calculations revealed that low transverse loadings alone caused a considerable loss in the load-carrying capacity. Moreover, through the formulation of a new creep coefficient function from a solution to the relaxation problem, the time-dependent stress–strain behavior and capacity loss were accurately captured using a series of equivalent short-term static analyses. The numerical investigations determined that this creep coefficient function had extremely low sensitivity to load amplitudes, which was predominantly a function of the loading duration. It was quantitatively verified that genetic creep can reduce the load capacity of structural members by a maximum of 30%.

Keywords: concrete; reinforcement; hereditary creep; creep coefficient function; load-carrying capacity.

Date submitted: 05.08.2025    Date accepted: 16.11.2025

References

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Visbreaking, despite its technological simplicity, enables the production of furnace fuel of the required quality without using light fuel fractions, allows residual fractions to be converted into distillate fractions, and provides additional recovery of medium and light fuel fractions. The incorporation of visbreaking in the scheme of oil refineries is especially important due to the need for deep processing of heavy residues and the increasing demand for distillate products. In this study, the aquavisbreaking of fuel oil and its mixtures with 5–10 wt.% water using magnetite as catalysts was investigated. It was found that, compared with conventional visbreaking, the addition of 5–10 wt.% water and magnetite increased the yield of the gasoline fraction by 2.9% and the light gasoil fraction by 4.6%, while the coke yield decreased by 5.1%. The hydrogen yield in the gas phase increased by a factor of 2.8–4.75. In gasoline and diesel fractions, there is a decrease in the amount of olefins and aromatic hydrocarbons with a simultaneous increase in the content of paraffin and naphthenic hydrocarbons. The results demonstrate that the use of magnetite in the aquavisbreaking of fuel oil improves the yield of light fractions, reduces the formation of coke, and significantly increases hydrogen production, alters the composition of the hydrocarbon fractions obtained, enhances their quality, and improves overall process efficiency.

Keywords: hydrocarbon feedstock; aquavisbreaking; heavy oil; magnetite.

Date submitted: 10.04.2025    Date accepted: 05.11.2025

References

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This article presents a comprehensive review and systematization of scientific studies on the synthesis of mono- and diesters of aliphatic, alicyclic, and aromatic carboxylic acids with mono- and polyhydric alcohols using homogeneous (HCl, H₂SO₄, HClO₄) and heterogeneous catalysts such as naphthenates, metal oxides, and micro-/nano-sized TiO₂ and ZnO. The influence of catalyst type and dosage, reaction temperature, and reactant molar ratio on esterification efficiency is analyzed to determine optimal reaction conditions, and probable reaction mechanisms are proposed. A one-step, cost-effective, and environmentally friendly esterification approach is highlighted, eliminating intermediate stages such as neutralization, washing, and drying. The synthesized esters are characterized by their physicochemical properties, and their structures are elucidated using modern analytical techniques. Special attention is given to the practical applications of carboxylic acid esters. These compounds are widely used as plasticizers in polymeric materials and cellulose derivatives, as antioxidant-depressant additives in diesel fuels, as lubricant additives, and in cosmetics and agriculture. Synthetic polymer resins occupy a special place among industrial organic chemistry products due to the diversity and scale of their production and processing fields. Currently, plastics rank first in the petrochemical industry in terms of production volume and capital investment, where plasticizers are essential components. Materials such as nitrocellulose, polyvinyl chloride, and polyamides cannot be efficiently utilized without suitable plasticizers. Therefore, this review emphasizes the role of ester compounds in improving the flexibility, durability, and processability of polymers and highlights their applications in the production of plastic pipes, electrical and mechanical engineering materials, fuel and lubricant formulations, cosmetics, agriculture, and the leather industry.

Keywords: carboxylic acids; mono- and polyhydric alcohols; esterification; catalyst; plasticizer; antioxidant.

Date submitted: 21.07.2025    Date accepted: 30.01.2026

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This study develops a dynamic programming model for optimal resource allocation in energy production, focusing on oil, gas, and renewable energy sources. Efficient management of energy resources has become increasingly important due to growing global energy demand, market uncertainty, and environmental sustainability challenges. In this context, the rational distribution of limited energy resources requires analytically grounded and economically efficient decision-making mechanisms. The primary objective of the research is to construct a multi-period optimization framework that determines the optimal allocation strategy while balancing profitability and environmental considerations. The proposed model applies dynamic programming techniques to evaluate intertemporal resource distribution under changing production capacities, cost structures, and ecological constraints. The analytical structure integrates mathematical formulations, scenario-based simulations, and comparative assessments to examine alternative development pathways in the energy sector. A central contribution of the study is the introduction of a time-dependent optimal balance mechanism that incorporates both conventional energy resources and renewable alternatives within a unified optimization system. The findings indicate that dynamically optimized allocation improves overall efficiency, enhances economic performance, and supports a gradual transition toward sustainable energy systems. The proposed framework offers policymakers and energy planners a flexible and scientifically grounded tool for long-term strategic planning and for the formulation of balanced, economically viable, and environmentally responsible energy policies.

Keywords: dynamic programming; energy resource allocation; oil and gas industry; renewable energy systems; mathematical optimization; sustainable energy management; multi-period modeling; energy policy planning.

Date submitted: 22.07.2025    Date accepted: 24.02.2026

References

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The process of drilling wells is accompanied by the formation of drilling waste with varying degrees of environmental hazard. During drilling, the primary environmental contaminants are underground waters (geological environment), hydrosphere, and lithosphere (open water bodies, waterbed areas, soil-plant cover). Pollution sources arise from the drilling process itself. These are generally classified into two groups: permanent and temporary. It is noteworthy that technological drilling waste, which accumulates and is stored directly at the drilling site, poses the greatest danger to the natural environment. With the increase in drilling depths and the expansion of the range of drilling fluids and reagents used, emissions into the ecosystem have also increased. As a result, the danger posed by drilling waste, which contains various pollutants, is growing. Therefore, studying the composition, comparative analysis in relation to the maximum allowable concentrations, the degree of danger, and the impact of these concentrations on water and soil environments remain critical issues today. The article presented focuses on analyzing the composition of drilling waste, determining the concentrations of harmful substances, comparing them with maximum allowable concentrations, and assessing ecological risks. A correlation between actual and maximum allowable concentrations of heavy metals in drilling waste was established. A relationship was found between the frequency of exceeding actual heavy metal concentrations relative to their maximum allowable concentrations and the consequences for the first two danger classes. The ecological risk assessment due to the harmful effects of heavy metals in drilling sludge is also provided.

Keywords: environment; drilling waste; ecological risk; maximum allowable concentration.

Date submitted: 18.07.2025    Date accepted: 26.11.2025

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Effective monitoring of oil spills is critical for environmental protection and operational safety in offshore oil and gas production areas. This study presents an automated oil spill detection system for the offshore environment using satellite imagery and advanced deep learning techniques. A key challenge in deploying AI-based detection systems is the scarcity of annotated training data, as manual pixel-level labeling of oil spill imagery is both time-consuming and costly, particularly in large-scale maritime settings. To address this limitation, we propose a domain adaptation methodology that combines synthetically generated training data with unsupervised domain adaptation techniques, significantly reducing annotation requirements while improving generalization across diverse environmental conditions. Our approach integrates temporal fusion of multi-temporal satellite imagery, Discrete Cosine Transform (DCT) frequency domain processing, and adversarial domain adaptation to effectively bridge the distributional gap between synthetic and real satellite imagery. Experimental results demonstrate that the proposed SegFormer-B3 architecture achieves 71.3% Intersection over Union (IoU) for oil spill detection, representing a 73% relative improvement over baseline methods trained only on automatically annotated data. The system efficiently processes periodic satellite coverage within operational timeframes, enabling automated first-line screening with human oversight for timely and informed response. This methodology addresses a critical need in offshore operations, providing a cost-effective and scalable solution for environmental monitoring that substantially reduces manual annotation effort while maintaining high detection accuracy across varying sea surface conditions.

Keywords: semantic segmentation; computer vision; satellite imagery; domain adaptation; discrete cosine transform.

Date submitted: 07.12.2025    Date accepted: 02.03.2026

References

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With the beginning of the economic reconstruction of Azerbaijan’s Karabakh region in 2020, there is a possibility for the development of a new tool for the revitalization of the region – renewable energy. This study focuses on the economic aspects of the development of renewable energy in Karabakh, with special emphasis on their contribution to regional revitalization, energy security, and economic diversification. The Karabakh region has tremendous potential for solar, wind, and hydro energy use, and therefore it is possible to integrate the system of renewable energy into newly constructed infrastructure in a cost-efficient and technically advanced way. The development of renewable energy sources would also add to capital investments, create jobs, and build up associated sectors such as construction, services, and grids. Finally, the creation of «green energy zones» in Karabakh is likely to attract investments through policies and cooperation with private sectors. From an economic point of view, the development of renewable energy sources will reduce the cost of energy in the long term, make the country less dependent on fossil fuels, and contribute to the security of energy supply. The paper also points out the most important economic challenges in this sector, such as high start-up costs, infrastructure, and the need for highly qualified personnel. Despite these factors, the development of renewable energy in Karabakh is an important economic opportunity for Azerbaijan.

Keywords: green energy zone; solar and wind power; Karabakh region; Azerbaijan; renewable energy; and economic development.

Date submitted: 07.12.2025    Date accepted: 02.03.2026

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The problem of synthesizing optimal stabilization of oil production is formulated within the framework of a linear-quadratic optimization problem using a mathematical model of the gas-lift process. This formulation captures the essential dynamics of the interaction between injected gas and produced fluids, allowing for a systematic analysis of the gas-liquid mixture (GLM) flow behavior. It is shown that the construction of optimal controllers can be reduced to the problem of partial periodic optimal stabilization of the GLM flow in the gas-lift process. The problem is considered in a time-averaged linear-quadratic approximation, where the control variable is restricted to the initial value, namely the injected gas. Under this assumption, it is demonstrated that the solution of the control problem reduces to solving a periodic matrix Riccati equation. Furthermore, this periodic problem can be transformed into an equivalent matrix algebraic Riccati equation, whose positive definite solution ensures system stability and optimality. Since the gas-lift process aims at maximizing the extraction of the GLM formed at the bottom of the well, particularly the mixture accumulated at the lift shoe, it is reasonable to impose a periodicity condition in this region. Additionally, a periodicity condition is introduced at the midpoint of the interval, corresponding to the rising phase of the GLM. It is also shown that, in certain cases, the matrix algebraic Riccati equation reduces to a matrix Lyapunov equation.

Keywords: synthesis problem; optimal stabilization; gas lift method; Euler-Lagrange equations; matrix algebraic Riccati equation.

Date submitted: 24.09.2025    Date accepted: 22.01.2026

References

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It is known that oil compounds are capable of rotating the plane of polarization of light by a certain angle of rotation, thereby forming the optical activity of oil. The value of the specific angle of rotation for oils is usually within 1-47 degrees with a positive value. However, it is also known that biomarkers, phytosterols, sterols and other relict compounds contained in oils are capable of rotating the plane of polarization of light to the left, i.e. exhibiting a negative angle of rotation. This tendency is observed in equatorial oils, in particular, oils from Java, Argentina, Borneo, and these oils have a negative angle of rotation. Further studies led scientists to the conclusion that the optical activity of oil is directly related to the fractional composition of oil, namely, with an increase in the boiling point of oil, the value of its optical activity increases. In light oil fractions, optical activity is practically not observed. The significance of optical activity of oil is as follows: The purpose of this study was to study the optical activity of some Azerbaijani oils, namely oil from the Zagly, Jafarly and Naftalan fields. The task was to compare the optical activity of these oils, as well as to identify the correlation between the fractional composition of these oils and their optical activity. The results obtained as a result of the studies showed that Azerbaijani oils have moderate optical activity, and the optical activity of Naftalan oil is higher than that of other studied Azerbaijani oils.

Keywords: optical activity; Azerbaijani oils; biomarkers; phytosterols; hopanes; steranes; oleananans.

Date submitted: 24.09.2025    Date accepted: 22.01.2026

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