In hydrocarbon reserves evaluation, reservoir rocks are commonly distinguished according to their fluid saturation using a threshold value of reservoir water resistivity. This parameter is usually derived from the chemical composition of formation water recalculated to an equivalent NaCl concentration. However, the existing method introduces significant errors when reservoir water contain elevated concentrations of hydrocarbonate ions (HCO₃⁻). Accordingly, this method cannot be used for hydrocarbon fields in the northern part of the West Siberian Basin, where groundwater often contains high levels of dissolved hydrocarbonate. To study the influence of reservoir water chemical composition on value of electrical resistivity, the authors of this article consider the results of determining the resistivity of reservoir water done in laboratory conditions obtained from 127 water models that closely replicate the composition of natural reservoir water under different temperatures from 20 to 100 °C. As a result of studies, the authors found that to obtain the values of the resistivity of reservoir water at any content of hydrocarbonate ion, it is expedient to use a formula that takes into account mineralization obtained from the dry residue in laboratory conditions. When the hydrocarbon content is below 10% for determining standard method also produces reliable results.

Accurate initial penetration of the top of the stratigraphic of target formation during drilling of tangent section in wells is a key to the successful drilling of the horizontal wellbore section. Based on the analysis of geological features of Cretaceous and Jurassic system, formations can be conditionally divided into two groups: laterally continuous layers and heterogeneous intervals containing pinch-outs or interbedded units. These features affect both the total formation thickness and the absolute depth of underlying boundaries. An important objective during top penetration in horizontal well drilling is not only the correct identification of the formation boundary under limited data availability, but also the prediction of the reservoir top relative to the stratigraphic top. It is important to note that during drilling of the tangent section of horizontal well, only gamma-ray data, inclination measurements, and geological and technical studies data are available in real time. Entering and transmitting of full suites of wellbores geophysical studies become available only during drilling of the horizontal section. Forecast of the penetration of the formation top and updating of the 3D geological model based on results of the penetration of the formation top are performed during drilling services of a tangent section by geological and geophysical methods. Initial penetration with a tangent section of the Vasyuganskaya suite top is challenging due to stratigraphic uncertainty in interwell space, caused by the overlying Georgievskaya and Bazhenov suites. The objective of drilling services in tangent sections is to accurately forecast the stratigraphic of the Vasyuganskaya suite top. This work examines specific cases of J1(1) formation top penetration that can be used as a basis for developing a methodology for forecast stratigraphic tops under conditions of limited geological and geophysical information. Analyzing and preparing recommendation the author considered gamma-ray data, sludge data, results of three-dimensional geological modeling, interpretations of wellbore geological and geophysical studies, and the results of seismicgeological modeling.

During exploratory well drilling in the territory of the Yamalo-Nenets Autonomous Okrug, gas saturation of the lower sub-suite of the Berezovskaya suite (reservoir NB1) was found. This discovery was identified due to gas manifestations during the reservoirs drilling in the upper part of the section. The lithological characteristics of these sediments are represented by opoka, clayey opoka, opoka-like clays. These rocks differ significantly in their terms of textural and structural characteristics from the rocks of the immediate surroundings (Cenomanian sediments). These sediments can be found in a number of fields in the Yamalo-Nenets Autonomous Okrug: Komsomolskoye, Gubkinskoye, Severo-Gubkinskoye, Yety-Purovskoye and others. In this article, the supra-Cenomanian sediments of the Lower Berezovskaya subsuite of the Upper Cretaceous are the object of study. Interest in studying the reservoir during the operational interpretation of geophysical research materials is caused by the fact that gas inflow was obtained in well 431 of the Komsomolskoye field in the interval of 786-803 meters. For express assessment of the saturation character of the NB1 reservoir, the author of this article develops some methodical techniques for identifying this reservoir using GIS methods with a forecast of the saturation character. For this aim, the author considers a number of wells of the Komsomolskoye and Gubkinskoye fields.

This article provides a systematic review of modern technologies for the demetallization of heavy oil raw materials. High concentrations of vanadium, nickel, and calcium in the form of stable metalloporphyrin complexes poses a critical challenge for the refining industry. This challenge causes rapid and irreversible deactivation of hydrotreating and cracking catalysts by pore blockage and poisoning active sites. The authors of this work conduct a critical analysis the established industrial method of hydrodemetallization and pointed out its inherent drawbacks (high energy intensity, hydrogen consumption, and catalyst decay). The researchers also analyze a wide spectrum of innovative alternative approaches. These approaches include advanced sorption and chelation techniques using functionalized silica and polymeric materials, such as the APEAA–HEA–MA terpolymer, as well as electrochemical, microwave-assisted, supercritical-fluid, and emerging bioengineering methods. A comparative analysis highlights the high efficiency of these methods, with removal rates reaching 96% for V, 91% for Ni l, and 98% for Ca. Furthermore, the article discusses technologies for recovering valuable metals from processing residues, such as spent catalysts and ash. The authors conclude that the future of the industry is linked to developing integrated hybrid systems, which combine the strengths of various methods within a circular economy framework to achieve optimal technical, economic, and environmental performance in heavy oil upgrading.

The development and operation of multilayer oil deposits are often accompanied by complications in the production of well products. The most characteristic of these include complications caused by high viscosity, gas content, waterlogging, paraffinic hydrocarbons, inorganic salts, aggressive components of water media, etc., leading to increased loads on well equipment, reduced pumping supply and maintenance period. Crude oil production from multilayer deposits involves the creation of complex underground well equipment designs for independent production and measurement from each layer. To accurately measure oil well production under these conditions, it is necessary to develop and implement innovative tools that have passed state certification and have low measurement error for product parameters within a wide range of variation. Control over the development of oil and gas fields and the depletion of their reserves, in accordance with the "Rules for Preparing Projects for the Development of Hydrocarbon Fields, approved by Order No. 639 of the Ministry of Natural Resources and Environment of the Russian Federation dated September 20, 2019," involves conducting relevant field studies and measurements. The largest volume of them is aimed at measuring the mass flow rate of crude oil, the water content of the well fluid, the density of oil and associated water, the volume content of free and dissolved gas in oil, followed by calculation of the current gas factor of oil, as well as the content of mechanical impurities in the liquid (TVP – solid suspended particles). The aim of developing the descriptions of new means and methods of measuring well products below is to provide subsoil users with an innovative tool that meets the requirements of import substitution, reliability and service life, low cost, as well as the speed and short time of measurements on wells. They are designed to measure 3-phase products of oil wells with high viscosity and gas content.

Gear drives are a key link for transmitting torque in most machines. Improving the loadbearing characteristics of gear drives is an actual scientific problem. Solving it will enable reducing the mass and dimensional parameters of gear drives. A promising approach to improving loadbearing capacity of gear drives is the use of arched-tooth gears. These gears provide smoother meshing, increase durability, and improve vibrational properties. However, installation and maintenance of gear transmission with arch gearing require high accuracy. This problem can be solved by using arched-tooth gears with self-aligning gears. This study aims to develop a mathematical framework for analyzing the dynamics of adaptive cylindrical gear drives with arched teeth with self-aligning wheels. The work applies analytical methods of mechanics. The authors of this article received mathematical expressions describing the motion of such gear systems, including possible oscillatory behavior of self-aligning gears. Researchers also determine the parameters of a damping device required to stabilize the system dynamics.

West Siberia is the largest hydrocarbon production region in Russia. At present, production from conventional reserves has significantly declined, which has led to increased development of hard-to-recover resources. These resources have high oil viscosity and density, as well as very low reservoir permeability. Most of these deposits are associated with complex clinoform systems of the Lower Cretaceous. These deposits show strong vertical and lateral heterogeneity. Such heterogeneity reduces the efficiency of conventional development methods. Consequently, there is a high demand for finding alternative solutions for additional reserves recovery, distinct from depletion-drive systems. The article considers modern methods for optimizing the development of lowpermeability reservoirs in the Achimov sequence. The authors analyze solution approaches aimed at increasing recoverable reserves and highlight their positive and negative aspects. Also, the researchers identify the main provisions of the methodology, the shortcomings of the applied technologies and different solution approaches. The article demonstrates the effectiveness of waterflooding in Achimov sediments when using low-mineralized water.

The article deals with the important problem of gas hydrate formation in gascondensate fields of the Yamal-Nenets Autonomous Okrug, which significantly affects production reliability and efficiency. This study aims to evaluate the conditions of gas hydrate formation and to select optimal inhibitors to prevent hydrate plug formation. In this work, the author uses thermobaric modeling in the HYSYS software environment to identify hydrate formation risk zones within the production gathering system. The results enable to find dangerous hydrate zones in the production gathering system. The experimental studies carried out using the RC5 setup confirm the high efficiency of kinetic inhibitors at very low dosages, providing long-term prevention of hydrate formation. Furthermore, the author conducted a comparative analysis of thermodynamic and kinetic inhibitors, which shows that kinetic inhibitors significantly reduce operating costs compared to traditional methanol injection. The key results of this study demonstrate the practical feasibility of implementing kinetic inhibitors to enhance both safety and economic efficiency in the operation of Yamal-Nenets gas-condensate fields.

In field pipeline construction for oil and gas fields located in permafrost conditions, above-ground pipeline installation on supports is predominantly used. A critical parameter in this case is the span between supports, which must be selected to avoid resonance conditions associated with vortex-induced vibrations caused by wind loading. This work aims to determine the span length between supports of pipe laid, and this value may be adjusted based on the assessment of wind-induced resonance. For this aim, the author of this article need to know the natural frequencies of the pipeline spans. To access the influence of the initial stress state of the pipeline on natural frequencies, researchers use a previously developed mathematical model based on the equation of transverse beam vibrations with axial force effects. The study shows that axial loads have the strongest impact: natural frequencies increase with the magnitude of axial force, regardless of whether the stress state is tensile or compressive. Transverse loads have a minor impact, but they should still be included for accurate frequency estimation.