The journal publishes materials based on the results of scientific and productive activity in the field of oil and gas complex in the following directions: Geology, exploration and geophysics of oil and gas fields Scientific and technical problems of petroleum engineering Materials, structures and equipment of petroleum complex facilities New solutions in modern equipment and technology
Study of parameters of fishing magnet systems
During the construction of oil and gas wells, metal debris accumulates at the bottomholes. It is not completely removed to the surface by the flow of drilling fluid but remains throughout the drilling process, causing accelerated wear of rock-destroying tools. To reduce accident rates and improve the technical and economic performance of drilling, it is necessary to clean the bottomhole from cuttings and metal particles. One of the most effective methods for cleaning the bottomhole from metal particles is the use of fishing magnets. An analysis of the operating conditions of fishing tools has shown that their performance is significantly influenced by design factors, including the dimensions of the magnetic system elements and their relative arrangement. The aim of the research is to study the influence of design characteristics on the efficiency of fishing magnets. The magnetic system was developed, taking into account the operating conditions of the tools in the well. To determine the optimal dimensions of permanent magnets and magnetic cores, theoretical studies of the systems’ magnetic characteristics were conducted. Three-dimensional models were developed, and calculations were performed in the ANSYS Electronics Desktop environment. As a result, the distribution of magnetic flux density on the surface and at the working gap of magnetic systems with different magnet lengths was obtained. It was found that varying the length of the permanent magnet from 6 mm to 10 mm has little effect on the magnetic flux density distribution, maintaining a similar field pattern and magnitude. Considering the efficient utilization of magnetic field energy, the most optimal configuration comprises a 6 mm magnet length and a 20 mm magnetic core length, with the cores operating close to the saturation limit of the soft magnetic material.
Copyright (c) 2025 Oil and Gas Power Engineering https://creativecommons.org/licenses/by-sa/4.0
Optimization of the operation of a multicyclone dust collector in the conditions of compressor and gas distribution stations based on cfd modelling
This article presents the results of a numerical model of the natural gas purification process in a GP-604 multi-cyclone dust collector, which is used at compressor stations on main gas pipelines to remove solid mechanical impurities before gas is supplied to turbocompressor units. Due to the complex structure of the internal flows and the interaction between the gas and solid phases, the study was conducted using computational fluid dynamics (CFD) methods within the ANSYS Fluent R18.1 software environment. Turbulence was described using the k–ε model, which allows for flow mixing and vortex structure formation. The motion of the dispersed phase was reproduced using a discrete phase model (DPM), which enabled the trajectories of particles in the flow to be determined and their deposition efficiency in different zones of the apparatus to be assessed. Regularities in the formation of rotating flows and recirculation zones, as well as their influence on the hydrodynamics inside the multicyclone, have been established. This is of great importance for increasing cleaning efficiency. The deposition efficiency as a function of particle size has been calculated: for diameters of 12–23 µm, it reaches 95–99%, whereas for particles smaller than 5 µm, it is approximately 87–90%. Additionally, an analysis of the influence of gas flow velocity, cyclone geometry and input flow distribution on device efficiency has been conducted, enabling more accurate prediction of its behaviour in different modes. The modelling results showed that cleaning efficiency largely depends on the uniformity of flow distribution between individual cyclones and the accuracy of the parameters used in the numerical model. The agreement between the obtained data and the operational characteristics of the device confirms the adequacy of the applied CFD models and their suitability for optimising dust collector designs in gas transportation systems. CFD is therefore a powerful tool for engineering analysis in the design, modernisation and maintenance of natural gas purification equipment. Further research could focus on studying the influence of the device's operating temperature and pressure conditions, analysing the behaviour of particles of different natures and densities, and optimising the geometric parameters of the multicyclone to maximise the removal of the smallest impurities. Additionally, these results could inform the development of new design solutions for dust collectors and provide recommendations for operating compressor stations under real industrial gas supply conditions.
Gasdynamic parameters of gas distribution networks after reconstruction using the technology of drawing of a polyethylene pipe into a steel gas pipeline
Gas distribution networks of Ukraine, which are constructed of steel pipes, are characterized by a long service life. An important condition for ensuring reliable gas supply is their reconstruction with the replacement of worn steel pipes with polyethylene ones. One of the progressive reconstruction technologies is the pulling of a polyethylene gas pipeline into a worn steel pipe. The implementation of such a reconstruction technology in the conditions of Ukraine will not only restore the functioning of the gas supply system, but also create conditions for reliable transportation of not only gas, but also gas-hydrogen mixtures. The reconstruction of the gas distribution network involves changing the diameters of sections, the roughness of the pipe surface and the properties of the transported medium, which significantly affects the operating modes. The purpose of the work is to establish the patterns of changes in the gas-dynamic energy consumption of gas distribution networks after reconstruction using the technology of pulling a polyethylene gas pipeline into a worn steel gas pipeline for the transportation of both natural gas and gas-hydrogen mixtures. The physical, thermodynamic and energy characteristics of natural gas and gas-hydrogen mixtures have been determined in accordance with the requirements of current standards. The patterns of change in the gas-dynamic energy consumption of an element of the gas supply system after replacing a steel gas pipeline with a polyethylene one at different degrees of its loading when transporting natural gas have been established. The need to change the operating pressure in a polyethylene gas pipeline after reconstruction from low to medium has been confirmed. The increased consumption of gas-hydrogen mixtures in a polyethylene gas pipeline has been determined to preserve the amount of energy that natural gas provided before the recon-struction of the network. Analytical dependences of the specific gas-dynamic energy consumption of polyethylene gas pipelines on the degree of their loading and the molar concentration of hydrogen in the gas-hydrogen mixture have been obtained for a number of cases recommended by the regulatory document for replacing steel pipes with polyethylene pipes.
Dynamics of changes in static secondary filtration of drilling muds depending on the content of acrylic reagents
The cause of hydration and swelling of clay minerals in rock mass most often is the filtrate of water-based drilling fluids. The volume of filtrate depends on the pressure drop in the well, the porosity and permeability of the rock. In such cases, there is a need to create a dense impermeable barrier on the walls of the well, and the filtration crust can serve as such a barrier if its permeability to filtrate is lower than the permeability of the rock mass. During the circulation of the drilling fluid, favourable conditions arise for the formation of a filtration screen, and to ensure its low hydrodynamic characteristics, reagents are added to the drilling fluid to reduce the filtration index. The article discusses the effect of acrylic polymer-based reagents that serve as flocculants, rheological parameter regulators, and stabilisers of filtration and thixotropic properties, in particular POLYPLUS, SYPAN, and POLYGUM. Laboratory studies were conducted to determine the dependence of the filtration index under static conditions and the thickness of the filtration crust on the content of these reagents, and it was found that SYPAN best reduces the filtration index at a concentration of 0.8–1.0% to 3 cm3/30 min, with the addition of POLYGUM at a concentration of 0.8–1.0% and POLYPLUS at a concentration of 0.07–0.1%, the filtration index decreased only to 4–7 cm3/30 min. To study the influence of the studied polymer chemical reagents on the formation of filtration crust properties, in particular, thickness, permeability, porosity, and density, experimental studies were carried out on models of fresh, mineralised, and salt-saturated drilling fluid filtrate, during which the effectiveness of the reagents was evaluated by the secondary filtration index of the crust. The addition of POLYPLUS contributed to a reduction in secondary filtration by approximately 1.5 times and, characteristically, for the salt-saturated solution model, this indicator is almost three times lower compared to the models of fresh and mineralised solutions. Similar laboratory studies of the effect of SYPAN and POLYGUM confirmed the regularity of the previous experiments. Based on the obtained values of secondary filtration, calculations of the permeability of the filtration crust were performed, which allow selecting a reagent that ensures the formation of its quality indicators and significantly reduces the intensity of the filtration process.
Investigation of the stress-deformed state of the well jet pump elements
The stress-deformed state of the well jet pumps is determined by their purpose and conditions of use. The main schemes for the use of ejection systems in the well are represented by the constructions of jet pumps intended for drilling, elimination of accidents in the process of drilling and operation of wells. By the nature of the impact of operating conditions on the mechanical characteristics, the components of the ejection system are grouped by the elements that are worn due to the hydraulic effect of the working environment and the body parts that perceive efforts from axial load, pressure and friction. The consumption of well jet pumps is complicated by the features of its workflow, which are the increased probability of its operation in the cavitation mode. In the process of analyzing the conditions of ex-platform of the wells of the surgery ejection systems, it is established that the annular stresses in the drilling process remain unchanged, and compression tension and tangent are observed asymmetrical hara. Unchanged stresses from the action of working fluid and axial loading and variable asymmetric stresses are characteristic of the body elements of the jet pump, which implements the process of purifying the hollow. During the elimination of the drilling column, the permanent stresses from the action of pressure and tensile at separate stages of the use of jumpers of the pump are transformed into asymmetrical extinct variable stresses. The cabinet elements of packer oil jet pumps are marked by the action of constant compression voltage, and two-pipe oil production systems are constantly stretched. Ring in the housing of the well ejection system and the density of the washing solution, the depth of the drill-wine, the flow rate of the working flow and the radius of the wall of the jet pump are associated with direct-proportional dependent. Increasing the diameter of the working nozzle and the column of lifting pipes causes a decrease in the value of the annular stress. The value of axial stresses and the radius and the thickness of the body wall are associated with a inverse pro-trial dependence.
Influence of natural factors on the intensity of stress corrosion of pipe steels during the operation of gas pipes
The paper examines the processes of influence of natural and technogenic factors on the intensity of emergency failures in the linear sections of main gas pipelines caused by corrosion cracking of pipe steel under mechanical stress. Particular attention is paid to the analysis of stress corrosion processes that occur during long-term operation of underground steel pipelines under variable climatic and soil conditions. The research is based on statistical information regarding the technical condition of the main gas pipelines “Bratstvo,” “Soyuz,” “Urengoy–Pomary–Uzhhorod,” and “Progress.” The analysis of the obtained data made it possible to establish the dynamics of changes in pipeline reliability depending on service life, design features, installation conditions, and the effectiveness of cathodic protection systems. Among the main factors determining the nature and rate of development of stress-corrosion damage, the following are considered: the operational lifetime of the gas pipeline, the magnitude of the electric potential of the cathodic protection system, seasonal fluctuations of soil temperature and moisture, as well as the type and physicochemical composition of the soil environment. It has been established that the combination of increased mechanical stress with an aggressive environment promotes the formation and propagation of microcracks, which over time lead to the development of deep corrosion defects and the destruction of pipe steel. Based on the conducted analysis, the regularities of the influence of these factors on the intensity of emergency failures caused by stress corrosion cracking have been determined. The obtained results have significant practical importance for predicting the durability of main gas pipelines, improving technical diagnostics methods, planning repair activities, and increasing the efficiency of electrochemical protection systems. The proposed approach makes it possible to develop a set of preventive measures aimed at reducing the risk of accidents, optimizing operating conditions, and enhancing the level of environmental and industrial safety during the transportation of natural gas
Evaluation of reservoir heterogeneity using well log curves
Each productive horizon, the subject of geo-logical and geophysical research, formed under unique conditions. Different types of rock facies can typically be grouped based on sediment accumulation environments (continental, deltaic or coastal-marine), the diagnostic features of these types and paleohydrodynamic sedimentation conditions. These groups share certain common geological and geophysical characteristics. However, these characteristics are generalised and de-scribe the reservoir as a whole without focusing on the details of its geological structure. Specifically, heterogeneities such as the presence of highly permeable layers within the formation, variability in filtration properties along the productive interval penetrated by the well, uneven distribution of fracturing or caverns and the nature of the cementing material are often overlooked. During the development of oil and gas fields, the geological features of reservoirs have a decisive impact on the efficiency of hydrocarbon recovery, often leading to premature water breakthrough or the formation of water coning. In the modern era, oil and gas field development projects are implemented using digital geological models as standard. These models are highly accurate due to the high level of detail of the reservoirs. This is achieved through a comprehensive set of geological, geophysical and production data, including core laboratory studies, well logging and trial and pilot pro-duction results, as well as modern mathematical and statistical processing methods. However, due to objective reasons, such datasets often lack either sufficient core material or data from the initial stages of reservoir development. Consequently, well logging curves remain the most readily available source of information. In our opinion, these curves offer extensive possibilities for assessing reservoir heterogeneities, many of which re-main unexplored by researchers. In this study, the authors propose a modified approach to using the Dakhnov–Archie formula, expressing it through the structur-al coefficient and utilising well logging data obtained through point-by-point interpretation for calculations. These calculated structural coefficients enable detailed assessment of the heterogeneity of the productive interval penetrated by the well, as well as prediction of fluid flow dynamics in different parts of the reservoir.
Forecast of hydrocarbon system parameters of the internal zone of the Precarpathian treatenant
A regional forecast of formation hydrocarbon systems for the gas fields of the Inner Zone of the Pre-Carpathian Depression has been produced. The company has conditionally allocated six areas, within which the individual fields and their structural blocks are located. The distribution of different types of hydrocarbon system has been modelled, enabling prediction at great depths in regions of high temperature and pressure in the initial stages of exploration. The peculiarity of establishing the forecast indicators lies in the fact that the thermobaric and physical parameters of the reservoir and reservoir oil are considered as combined average values within a single, integral Inner Tectonic Zone. Changes to each of these parameters were uniform and extended over the entire zone. The depths of fluid replacement were estimated by extrapolating the averaged G = f (H) curves. However, when such universal curves are used in practice, the reliability of finding the values of specific parameters is reduced to a certain extent. This is insufficient for the current stage of the fundamental study of the oil and gas potential of the Carpathian region. High reservoir temperatures only increase the intensity of the fluid separation process. Consequently, the recovery of conventional oils from deposits remains low and is very low in cases involving the development of transitional oils. Additionally, the issue of reservoir structure strength is important and currently poorly understood. When developing oil deposits in any mode (elastic or dissolved gas), reservoir pressure inevitably decreases. Graphs were built and the regression equations for the forecast parameters were derived. These are included in the formula for calculating hydrocarbon reserves by the volumetric method relative to the depths of the deposits. The regression equations for prediction in combination with laboratory studies of thermobaric conditions (pressure and temperature) with depth was derived, because information about them is needed to calculate individual parameters of hydrocarbon systems.
Identification of reservoir rocks in the geological section of the Visean deposits of the Lypovodolynske field
This paper focuses on identifying reservoir rocks within the Viséan deposits of the Lypovodolynske oil and gas condensate field, using an integrated analysis of well logging data (geophysical well surveys, GWS). The Viséan stage consists of lower and upper sublevels of terrigenous-carbonate sequences forming several prospective productive horizons. The study focuses on two types of reservoir rock: terrigenous rocks (such as sandstones and siltstones) and carbonate rocks (such as the limestones of the lower Viséan 'plate'), which differ in terms of their lithological composition, pore space structure and physical properties. Terrigenous reservoirs exhibit relatively uniform porosity and a clear response in geophysical fields, enabling them to be identified efficiently using traditional methods. In contrast, carbonate reservoirs are more difficult to recognise due to heterogeneous porosity, including secondary fracture and cavernous porosity, which affects the representation of geological parameters in GWS data. This work proposes a methodology that comprehensively correlates baseline and normalised (scaled) curves from various geophysical methods (gamma-ray logging, acoustic logging, lateral logging, neutron-gamma logging and pulsed neutron-neutron logging). This improves the accuracy with which reservoir layers can be identified. This approach identifies potential reservoir intervals when the normalised curve values exceed the baseline, enabling precise delineation of terrigenous and carbonate layers. Well No. 26-Lypovodolynska was used as a case study to construct a logging curve panel and determine reservoir intervals, with the results confirmed by actual oil and gas inflows. The study reveals that different combinations of logging curves yield slightly different reservoir intervals, indicating the presence of multiple porosity types within the geological section. Analysis of current international and Ukrainian research indicates that combining different GWS methods with mathematical models and machine learning techniques is the most effective way to enhance reservoir identification in complex carbonate formations. The results confirm the practical effectiveness and applicability of the proposed methodology in geological modelling, resource assessment and field development planning in oil and gas condensate fields with similar geological conditions. The study also emphasises the need to further develop integrated GWS data interpretation techniques adapted to the local features of reservoir rocks, in order to improve the accuracy with which they can be identified within the geological sections of wells.
Using neural networks to assess porosity and permeability of mountain rocks
The advent of artificial intelligence (AI) and its application in various industries has made it possible to automate and optimise many processes, including those in geophysics. Using AI in geophysical well surveys could transform the way data is collected, processed and interpreted. AI is expected to become a key tool in the oil and gas industry, advancing data modelling and analysis and offering significant benefits in terms of accuracy and efficiency. This paper presents an approach to estimating the porosity and permeability of rocks based on geophysical survey results, using a neural network as the primary tool. Porosity and permeability are key characteristics of reservoir formations and important parameters for design calculations and the development of productive horizons in oil and gas fields. The main difficulty in determining these parameters is that they are dependent on many other factors. Emerging information technologies offer opportunities to identify complex relationships between diverse geological and geophysical parameters. An artificial neural network model has been developed to predict the porosity and permeability coefficients of rocks, based on an in-depth analysis of geophysical data. This approach enables hidden relationships between parameters to be identified that would go unnoticed when applying traditional analytical methods. The study achieved high accuracy in predicting porosity and permeability values, as confirmed by their alignment with the results of laboratory experiments. This demonstrates the effectiveness of using machine learning to automate the analysis of geophysical data, and the proposed approach has significant advantages in terms of speed and accuracy of analysis. This is especially important in situations where laboratory research is impossible or limited.The use of neural networks contributes to a deeper understanding of the impact of various factors on rock porosity and permeability, which is important for decision-making in the process of reservoir development.The novelty of this work is the creation of an integrated approach that combines classical geophysical methods with innovative machine learning algorithms. This combination provides fast and efficient determination of rock porosity and permeability, opening up new opportunities for optimising the processes of field exploration and development.
Evaluation of physicochemical properties and combustion performance of linseed oil-dee mixtures for diesel engines
This study focuses on the physicochemical and combustion properties of linseed oil (LO) blended with diethyl ether (DEE) and investigates its potential for application in diesel engines. While similar research exists for rapeseed oil (RO) and DEE blends, a detailed analysis of LO-DEE mixtures has been lacking. Linseed oil, a colourless to yellowish edible oil extracted from flax seeds, is notable for its high content of polyunsaturated fatty acids, especially α-linoleic acid. These properties make it suitable for multiple applications, including the chemical, biomedical, and fuel industries. However, LO's unique chemical composition presents opportunities and challenges for its use as a biofuel. Experimental results demonstrate a significant linear relationship between DEE concentration and the physicochemical properties of LO-DEE blends. For instance, density and surface tension decreased with increasing DEE content, leading to improved spray characteristics and atomization during fuel injection. The LHV of the blends was slightly reduced compared to diesel fuel (DF) but remained comparable to rapeseed oil-DEE mixtures. While LO's viscosity is lower than many vegetable oils, it remains higher than that of conventional diesel fuel, which can impact spray angle and atomization efficiency. The addition of DEE effectively reduced viscosity, enhancing the combustion process. Combustion analysis revealed that LO has a longer ignition delay compared to DF, primarily due to its high polyunsaturated fatty acid content. Blending with DEE significantly reduced the ignition delay, narrowing the gap between LO blends and DF, especially at higher engine speeds. Additionally, the high unsaturated fatty acid content contributes to increased NOx emissions and potential deposition issues on engine components. Preheating and engine modifications may help address these challenges but require further research. Statistical analysis using linear regression models confirmed the significance of the observed trends, with confidence intervals validating the reliability of the experimental data. The study emphasizes the importance of understanding the interplay between fuel properties, combustion behaviour, and engine performance to optimize the use of LO-DEE blends as a renewable alternative to diesel fuel.
Use of application software for calculations of thermal hydraulic characteristics of oil flow
The results of modelling non-isothermal oil movement in a section of the main oil pipeline are presented. It is emphasised that finding effective oil transportation methods through the pipeline system is a topical issue related to establishing rational pumping modes. The feasibility of using modern mathematical programming methods and application software is determined; however, the latter requires direct participation from programmer users with an understanding of the development area. To study the thermal and hydraulic characteristics of oil flow in an oil pipeline, it is necessary to consider many factors and select the correct determinants. The main stages of the modelling process are presented: construction of the oil pipeline geometry in the Fusion360 programme; compilation of a physical and chemical oil model in the PVTSim Nova programme; and modelling of heat transfer and hydrodynamics in the COMSOL Multiphysics programme. An example of the calculation of the transportation of heated viscous oil is given, in which the oil enters the main oil pipeline at a temperature of 50 °C. The pipeline is a shallow-laid underground pipeline at a depth of 0.9 m. The change in oil temperature along the cross-section and length of the channel was studied, taking into account losses to the environment. It has been proven that a decrease in soil temperature is accompanied by a decrease in oil temperature. This corresponds to the physical process of cooling a moving fluid in a pipeline. The temperature changes across the cross-section in accordance with physical laws, indicating the feasibility of using the selected program for thermal calculations. According to the modelling results, data on oil velocity and pressure changes along the length of the pipeline were obtained. The presented data on pressure changes takes into account costs along the length of the oil pipeline; however, it would also be possible to include the difference in geodetic heights and costs at local supports in the program.
Research on existing gps monitoring systems in motor vehicles
Transportation of cargos by vehicles accounts for the majority of the entire flow of goods. Starting from the transportation of raw materials and semi-finished products to factories and ending with the delivery of finished products to shops and directly to customers, vehicles are used. Against this background, the issue of monitoring vehicles arises, which is necessary for both safety and financial control reasons. After considering various options, GPS monitoring proved to be the most effective. A GPS monitoring system is a satellite system for tracking the location and status of any moving objects. GPS monitoring should not be viewed as a way to determine the position of a vehicle in space, but in a much broader sense. First of all, it is necessary to obtain data on the speed of delivery of goods by different routes. For companies that regularly deliver to the same cities, reducing the route by just a few kilometres and reducing delivery time by a few hours translates into significant savings on an annual basis. Satellite monitoring of motor vehicles is an effective solution that provides companies with real-time operational control. This tool allows you to monitor the work of drivers, prevent the misuse of vehicles and eliminate financial fraud, particularly related to fuel. The introduction of such control significantly saves time in the transportation of goods and solves typical problems inherent in modern vehicle fleets of any industry. A comprehensive freight transport monitoring system allows you to: exclude the misuse of wheeled vehicles and other machines; minimize the risk of fuel overconsumption; assess the qualifications of drivers and dispatchers; reduce downtime by calculating the delivery time for loading or unloading. All this leads to a decrease in the cost per ton-kilometer of delivered cargo. In conditions of fierce competition in the freight transportation market, this is a strong argument that will allow a transport company that wants not only to maintain its position in the market, but also to expand its presence.
Improvement of methods for researching the elemental composition of biofuels and raw materials for their production
Lignocellulosic biomass is a reliable source of renewable energy and important chemicals for industrial use. Its popularity is due to its high prevalence, limited environmental impact and relatively low price. One of the most promising methods for converting this type of raw material into biofuel is thermal treatment. Thermal treatment allows for the formation of a wide range of useful gaseous, liquid, and solid products depending on the reaction conditions. The main and most important factor determining the efficiency of processing is the elemental composition of the initial biomass, its change during processing, and the composition of the finished products. Rapid and reliable elemental analysis of biomass and its processing products is important for commercialising production. The paper discusses the main methods for determining the composition of biomass, in particular, classical, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray fluorescence analysis. The features of each method are analysed. The classical method used to determine the elemental composition of biomass is highly accurate but, at the same time, labour-intensive, expensive and requires the use of hazardous chemicals that generate large amounts of waste. The Fourier transform infrared spectroscopy (FTIR) method is quite effective for a faster assessment of the elemental composition of biomass, but it is considered insufficiently sensitive. X-ray photoelectron spectroscopy (XPS) is a surface-sensitive method and useful for studying the carbon, oxygen and nitrogen content in various organic materials, but to obtain accurate experimental data when using this method to determine the elemental composition of biomass, mathematical dependencies are required to calibrate the measuring instruments using the classical method. The use of X-ray fluorescence (XRF) to determine the chemical composition of biomass basically confirms the effectiveness of the method. The experimental data obtained have deviations in the range from ±10% to ±20%, which seems quite satisfactory for many applications. At the same time, for some elements, systematic errors (deviations) can be quite pronounced and amount to 50–100%. Therefore, in our opinion, this direction is at an early stage of development and needs improvement. The research conducted in this work gives grounds to conclude that non-destructive control methods that can be carried out on site are promising for determining the elemental composition of biomass during processing. This approach contributes to the commercialisation of biofuel production processes and trade in both raw materials and finished products.
Innovative and technological directions for improving the secondary energy use of decommissioned oil wells
The article explores comprehensive innovative and technological solutions aimed at intensifying the geothermal reutilization of depleted oil and gas wells. The purpose of the study is to verify technological approaches to the repurposing of well infrastructure in order to mobilize its geothermal potential and integrate it into low-carbon energy systems. The methodological framework is based on a synthesis of structural-functional analysis of modern well-modernization technologies with numerical modelling of thermohydrodynamic processes that determine the mechanisms of energy extraction. Additionally, a comparative assessment of the efficiency of alternative heat-exchange configurations, Organic Rankine Cycle (ORC) units, and underground thermal storage systems is conducted. The results demonstrate that the implementation of closed-loop geothermal systems combined with optimized heat-exchanger architectures significantly increases the stability and intensity of heat flow without risking geological degradation. It is established that the integration of low-temperature ORC modules enables efficient conversion of thermal energy from bottom-hole zones into electrical power, expanding the operational range for wells with limited temperature conditions. Modelling of interseasonal thermal storage systems (BTES/ATES) confirms their ability to ensure long-term energy retention, forming the foundation for autonomous energy microsystems based on decommissioned wells. The practical significance of the study lies in the development of scientifically grounded technological solutions that optimize the costs of well decommissioning by transforming these structures into elements of renewable energy infrastructure, achieving both economic and environmental benefits. The proposed technological approaches are applicable in industrial-site redevelopment and in shaping regional energy strategies. Prospects for further research include improving predictive models of thermal performance based on machine-intelligence algorithms.
Technical aspects of effective centering of casing strings
The article is devoted to the study of factors that determine the effective centering of casing strings in wells which include: the type of well, the geometric parameters of well, the casing string running depth and the length of casing centering interval; the intensity of the well deviation. The parameters of casing string should also be taken into account: the diameter of casing, the wall thickness; length of the casing string and grade of casing, and parameters of fluids in the well: density of drilling and cementing fluids, friction coefficient, consestivity of solids (abrasive) particles in the drilling fluid, thixotropic properties of fluid. The casing running process is significantly affected by the casing running speed, and the degree of replacement of drilling fluid with cement fluid is affected by the rotation and axial movement of casing string. It is necessary to take into account the data of the caliper log and inclination log, the graduation of hole temperature, the intervals of formations containing aggressive environments, and the interaction of the «centralizer device-rocks» system. Notice that centralizers must meet strict complexity of the requirements. Considered their design features, advantages and disadvantages of various types of centralizers: bow-spring, rigid, semi-rigid, mold-on and their purpose. The number of centralizersand their installiation sections should be justified based on the minimum number of casing sag points in the well ortheir complete absence. Nowadays is a trend in the manufacture of centralizers towards improving their design and using new, innovative combinations of materials and alloys with a low friction coefficient, which improves their functionality. The written work proposes a method for calculating the resistance force created by the strength bars of centralizer and calculation value for various types of rigid centralizers: RC 114/146-165-1; RC 146/222-251-1; RC 194/245-270-1; RC 351/445-490-1. The several important conclusions were made based on the results of calculations: increasing the size of centralizer leads to increasing the drag force; the resistance force depends on the geometric parameters of rigid bars and their number; increasing the friction coefficient (μ) from 0.2 to 0.3 leads to a significant increase in the resistance force for each centralizer (increase to ~25%).
Modelling the properties of gas-water mixtures for forecasting leakage parameters from distribution networks
Simple engineering mathematical models have been developed and validated to determine the key thermodynamic properties that form the basis for improving the accuracy of predicting leakage parameters of hydrogen-natural gas mixtures under the conditions of gas distribution networks. To create a reliable benchmark database for model development, a comprehensive array of values was generated in the PVTsim Nova software package using the fundamental GERG-2008 equation of state. The study encompassed fifty base component compositions of natural gas, reflecting the variability of its quality in the real networks of Ukraine. The modeling was performed for absolute pressures from 0.1 to 1.3 MPa and temperatures from 243.15 to 323.15 K, which fully covers the operating range of distribution networks. The molar content of hydrogen in the gas mixture varied from 0 to 20%. Based on the obtained data, power-law regression equations were developed to calculate the compressibility factor, adiabatic index, and speed of sound as functions of pressure, temperature, the relative density of the mixture with respect to air, and the molar concentration of hydrogen. Validation of the developed models was conducted by comparison with the benchmark data, establishing the high accuracy and adequacy of the proposed equations throughout the entire investigated range. It was determined that for the compressibility factor model, the maximum absolute relative error is 0.44%, and the coefficient of determination is 0.995. For the adiabatic index, the corresponding values are 0.93% and 0.914; for the speed of sound – 1.5% and 0.998. An analysis of the error distribution confirmed the stability of the models and revealed only minor systematic biases for the adiabatic index and speed of sound, which depend on the hydrogen content. The proposed mathematical models have a simple analytical structure and do not require iterative procedures, allowing for their direct implementation into engineering methodologies for the rapid calculation of leakage parameters and production-technological expenditures and losses of gas in distribution networks.
Systems for automatic supply of surfactants as a tool for stabilizing production
The article describes the study of the efficiency of automatic surfactant supply systems to substantiate the technological parameters of their use and optimise the operation of wells with high water cut. The objective of the study is to develop scientifically sound approaches to the selection and implementation of effective methods for removing fluid from the wellbore, taking into account their technical and operational parameters. The purpose of the study is to optimize technological parameters and select effective solutions for stable and uninterrupted supply of surfactants, which ensure increased productivity and reduced well operating costs. Calculations were performed to determine the minimum required gas flow rate, which showed that for none of the wells the condition of continuous fluid removal from the bottom is met. The minimum required gas flow rates, which are significantly higher than the actual flow rates, and the Froude parameters for gas and liquid flows, indicate this. Using the nomogram to select effective methods for intensifying fluid flow to the surface, it was concluded that the most optimal and effective method to counteract well watering would be an automatic surfactant supply system to the bottomhole zone. Further, laboratory tests of surfactant foaming agents of various modifications and concentrations were carried out. Namely: studying the solubility (compatibility) of surfactants in the formation fluid; comparative studies of the recovery capacity of the formation fluid with ‘SE’ type surfactants. The reservoir fluid from well M 226-Rudki was used as a sample. Studies on the selection of surfactants for the formation of foam with high foaming characteristics and the study of their recovery capacity were carried out on a reduced model well. The process of optimising the surfactant supply parameters includes the selection of such characteristics as flow rate, reagent consumption and surfactant concentration. The initial calculation was based on the actual gas velocity, which ranges from 0.89 to 1.29 m/s, and the minimum required gas velocity for stable operation and prevention of fluid accumulation in the wellbore, which ranges from 5.29 to 5.91 m/s. Based on laboratory studies of reservoir fluid and tests of the surfactant SE-235-A-S-30, the expediency of its use to increase the gas flow rate, which helps to stabilise well operations, has been substantiated. The industrial experience of well 226 at the Rudkivske gas field has shown that after the introduction of the technology for fluid recovery from the wellbore using an automatic surfactant supply system, the well began to operate stably. This ensures the complete removal of water from the wellbore and increases the well's flow rate by 22%.
Study of the impact of formation opening and depression in wells on the development of gas reservoirs with bottom water
The key features of gas reservoir development with bottom water are presented. The regularities of the formation process of cones of bottom water under production wells during reservoir development and watering are characterized. The results of modern national and international studies on the impact of the reservoir and well design's relative opening and anisotropy are analyzed. Using the Petrel&Eclipse program, the complex effect of the relative opening of the gas-bearing formation and the depression on the formation in the well (i.e. the gas withdrawal rate) on the cone formation process and the reservoir gas recovery factor during the waterless period of well operation was studied for a hypothetical square-shaped gas reservoir with a central production well. During the initial reservoir development period, the well was operated with a constant reservoir depression. After reducing the wellhead pressure to the established value (1.0 MPa), the well was switched to a constant wellhead pressure technological mode. Reservoir development ceased when the reservoir pressure decreased to 10% of the initial pressure or the water cone reached the lower holes of the perforation interval. Variants with reservoir pressures of 1.25 MPa (5% of the initial pressure) and 2.5 MPa (10% of the initial pressure), as well as different values of relative formation opening (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9), were studied. The research results are presented in two tables and in graphical form, showing the relationship between the final reservoir pressure and the gas recovery factor at the time when reservoir development ceases, and the relative formation opening. At a reservoir depression of 1.25 MPa, intervals with a relative formation opening of between 0.1 and 0.6 are not flooded by the end of the development period. With a relative pay of 0.6, the final gas recovery factor is 88.53%, and the duration of reservoir development is 17 years and 3 months. At a reservoir depression of 2.5 MPa, intervals with a relative pay of between 0.1 and 0.4 are not watered at the end of development. With a relative formation opening of 0.4, the final gas recovery factor is 90.46%, and the duration of reservoir development is 14 years and 2 months. Within the range of changes in reservoir depression from 1.25 to 2.5 MPa, the optimal value of relative pay is approximately 0.4 to 0.6. The critical value of the relative formation opening at which water breaks through to the wellbore is 0.64 at a formation pressure of 1.25 MPa, and 0.45 at a formation pressure of |2.5 MPa.
A review of studies on the phenomenon of bottom-water coning in oil and gas wells
Review articles play an important role in scientific research, summarising existing knowledge on a particular topic, assessing its relevance and identifying areas for further research. This paper analyses the results of theoretical and experimental studies on the influence of geological, physical and technological factors on the process of water ingress into production wells during the development of deposits with bottomhole water. The analysis covers a wide range of issues, including forecasting the development of the bottomhole water cone in vertical and horizontal wells, assessing critical water-free oil and gas flow rates, and the influence of formation anisotropy on the rise and fall of the water cone. Particular attention is paid to the effectiveness of various methods of combating water flooding, including limiting pressure depression on the formation, using water-proofing screens, joint extraction of oil or gas together with water, and periodic well operation technology to control the subsidence of the bottomhole water cone. Classic cone formation models, the results of mathematical calculations and their comparative analysis are considered. Particular emphasis is placed on how thoroughly the authors of the studies covered the topic, how critically they approached the evaluation of the research results, and whether they managed to formulate an objective and structured picture of the subject of the study. Based on the results of the analysis, the strengths and weaknesses of existing methods for predicting and combating cone formation of bottom water are identified, as well as their practical significance and prospects for further research in the field of managing the development of oil and gas fields underlain by bottom water. An important aspect of the work is the emphasis on the need for additional research on the patterns of rise and fall of the bottomhole cone during the development of gas and gas condensate deposits. The presented results may be useful both for scientists studying cone formation processes and for engineers working on optimising the development of deposits under water pressure conditions
Research on the energy efficiency of gas transport systems in combination with underground gas storage facilities
The problem of calculating a complex gas transportation system is considered, comprising gas pipelines forming a linear section, compressor stations, and an underground gas storage facility. These elements represent serially and parallelly connected links, and the throughput depends on their characteristics. The characteristics of the linear part and compressor stations are calculated and constructed in analytical form. A mathematical model for forecasting and optimising stationary modes is based on the characteristics of linear sections and compressor stations. By excluding intermediate pressures, a dependence is obtained to determine system performance. The model also includes pressure restrictions. Following implementation of the model, it was shown that the perfor-mance of the gas transportation system could be regulated by including or excluding the underground gas storage facility from the operating mode. The degree to which the CS operating parameters influence the system operating mode is also established. The proposed mathematical model is recommended for forecasting the operation of gas transportation systems in combination with underground gas storage facilities. The strategy for the rational use of underground gas storage facilities in pipeline transport, with a view to minimising energy consumption, is based on a study of the impact of such facilities on the regime of the gas transportation system and the amount of energy consumed. The aim is to analyse the dependence of energy consumption for gas transportation on the parameters of underground gas storage facility operation. The principle of using underground gas storage facilities to level out uneven gas consumption in long-distance gas transportation systems is that, first of all, underground gas storage facilities with the maximum volume of active gas and those closest to consumers should be used.
Research on how the form of vibration affects the efficiency of the axial oscillation tool
The paper evaluates the effectiveness of using axial vibration generators in drill strings with different forms of excitation force. The relevance of the study is due to the need to overcome significant friction forces and increase the mechanical drilling speed of inclined and horizontal wells. The research was conducted on the basis of numerical modelling using a simulation model of the drill string developed in the Modelica environment. The drill string is represented as a composite rod with parameters distributed along its length, with an axial vibration generator installed in an inclined well filled with flushing fluid. A simplified (soft-string) model of the drill string was used for modelling. The viscous interaction between the string and the flushing fluid is taken into account, and contact with the wellbore walls is described using the Stribeck friction model. Six types of vibration shapes were considered: harmonic, triangular, trapezoidal, the sum of two synchronous harmonic components, as well as modified triangular and trapezoidal. The selected forms correspond to the typical operating characteristics of existing axial vibration generators or, according to the literature review, should provide increased efficiency in overcoming friction forces and can be technologically implemented. All variants were modelled at the same excitation force frequency. The signal amplitudes were selected so that the root mean square value was the same for all shapes, corresponding to equal energy costs for creating vibrations. The results of modelling for a section of the drill string located in an inclined well with an azimuth angle of 39° showed that the trapezoidal shape of the vibrations is the most effective. In general, a comparative analysis shows that the efficiency of the axial vibration generator increases with an increase in the RMS of the normalised function describing the vibration shape. Therefore, the most effective vibration shapes are those that are flatter (less pointed) and more energy-intensive, which contributes to better transmission of axial load and reduction of friction forces.