The article presents the results of geochemical studies of organic matter and hydrocarbon gases in bottom sediments of the northeastern sector of the Barents Sea. The areas with thermally mature hydrocarbon compounds discharging into the upper part of the sedimentary section are identified. This is evidenced by biomarker indicators of organic matter maturity that are not characteristic of syngenetic hydrocarbon compounds of sediments, as well as by the molecular composition of hydrocarbon pore gases and the isotopic composition of methane carbon. Based on the areal distribution of the detected thermally mature hydrocarbon compounds in bottom sediments, a model of fluid discharge in the sedimentary cover is proposed, taking into account the peculiarities of the geological structure of the region. According to the obtained model, the greatest prospects for oil and gas accumulation within the northern and northeastern sectors of the Barents Sea are associated with the flanks of the North Barents Super Depression.
This study proposes an optimization-based approach to determine the actual fluid composition of gas condensate reservoirs when obtaining representative samples are impossible. The method incorporates the well tests hydrodynamic modeling, laboratory analyses of non-representative lean samples, and field data, including the gas-condensate ratio (GCR). The reservoir composition is assumed to be a linear combination of lean gas and its equilibrium condensate. The proportionality (mixing) parameter is obtained by minimizing the discrepancy between observed and simulated GCR values obtained using tNavigator. Two variants are considered: 1) a scalar parameter, corresponding to mixing of equilibrium gas and condensate; 2) a vector-valued mixing parameter, permitting per-component adjustment for improved accuracy. For the vector mixing parameter, a check is performed for compliance with the gamma distribution of the obtained heavy component fractions relative to their molecular weight. The approach is verified for a synthetic case with a known reservoir composition. For a detailed 34-component “lean”’ sample model, the scalar parameter approach accurately reproduces key PVT properties such as the dew point pressure and condensate dropout curve from constant-volume depletion tests. Reduced-component fluid models require the vector-valued mixing parameter to achieve comparable accuracy. To evaluate robustness against field uncertainties, Gaussian noise is introduced into the actual GCR data. Numerical experiments confirm that the method remains reliable if the error in noisy data does not exceed 10% relative to actual GCR.
In 2024, the first stage of geological and geophysical research was completed within the framework of the Federal project “Geology: The legend revival” (2022–2024). The exploration areas are located in the zone of the junction of the three largest superorder elements: the Anabar anteclise, the Vilyuisk syneclise and the Priverkhoyansk trough. The purpose of this publication is to clarify the geological structure and oil and gas potential of this area.Within the Anabar anteclise, on the Munsky arch there is a shortened type of section, there are no deposits of the coastal-continental Permo-Triassic formation with the Triassic and Permian Play, which are the most promising both in the Vilyuisk syneclise (confirmed by the presence of deposits on the Khapchagai shaft) and in the Predverkhoyansk marginal trough. However, there are Lower-Middle Cambrian, Vendian terrigenous and Vendian carbonate Play.The presence of a large number of shallow wells in the Munskaya area made it possible to reliably map the erosive upper boundary of the Cambrian sediments in seismic sections and to clarify the position of the structural plan on the underlying horizons. The contours of the Munsky arch and the thickness of the sedimentary cover have been clarified. Structurally, the area under study is a monocline slope, plunging southward from the Munsky Arch into the Vilyui syneclise. During detailed analysis of the structure of deposits in the Munsky area, much attention was paid to the dynamic analysis of the seismic record in order to search for non-anticlinal prospects.As a result, structural-stratigraphic and structural-lithological perspective objects in the Vendian deposits were mapped, which are clearly on the seismic sections.
A positive Eu-anomaly, extremely rare for this mineral, has been found for zircon from the silicate marbles of the Khapchan terrane of the Anabar Shield and syenites of the Sukharninsky complex of granitoids of Chukotka. In the silicate marble sample, a positive Eu-anomaly was found for late generation of zircon with an increased content of non-formula elements and volatile components. The age of zircon at the upper intersection is 1954±17 Ma (granulite metamorphism), the lower intersection is 984±49 Ma (tectonothermal event). Zircon with a positive Eu-anomaly tends to the lower intersection of discordia, which indicates a connection with late exposure to fluids. Zircon from syenites is characterized by black high-uranium marginal zones with a positive Eu-anomaly and enrichment with trace elements. The entire zircon forms a cluster with a concordant age of about 105 Ma. It is likely that the occurrence of a positive Eu-anomaly in zircon from syenites occurred as a result of the evolution of a closed magmatic system, without the involvement of an outside fluid. Zircon from silicate marble appears to have recorded the evolution of fluid composition: 1) the early fluid was enriched in boron and was predominantly aqueous, probably mobilized from the primary sedimentary protolith of silicate marbles; 2) the subsequent one, presumably separated in time from granulite metamorphism, was enriched in halogens (fluorine and chlorine), which was reflected in the composition of the late zircon generations. The paper shows that the lower intersection of the discordia, based on individual zircon generations with special geochemical characteristics (the content and spectra of REE, the amplitude and sign of the Ce- and Eu-anomalies, the content of non-formula trace elements, Th/U ratio), is very likely related to a real geological event rather than an analytical artifact.
The structure of the Chernyshev Swell is one of the main mysteries of the structural geology of the Timan-Pechora Basin. This fold-thrust zone is characterized by a set of features, including the significant remoteness of the Ural orogen, a high degree of deformation of its constituent rocks, the divergence of thrusts on its flanks, lateral segmentation, and disproportionately widespread development of upper Ordovician-lower Silurian sediments on the surface. An interpretation of the structure of the Chernyshev Swell is proposed, the main element of which is the presence of longterm salt diapirs that were squeezed during collisional shortening. Compression led to the formation of large thrust overlaps due to the transformation of salt walls into mushroom-shaped diapirs and salt-detached thrust sheets. The largest salt-detached thrusts are found in the transition zone between the Chernyshev Swell and the Kosyu-Rogov Trough, where the horizontal overlap is 15 km or more. Various traps in the Upper Ordovician-Permian sediments are predicted under allochthonous salts. The proposed interpretation can be used as an a priori geological model for processing seismic data. This will provide additional geologically significant information that will reduce the uncertainty of geological structures and allow definition of new hydrocarbon leads.
This study presents a comprehensive experimental and numerical investigation of a promising enhanced oil recovery (EOR) technology based on hydrogen peroxide (H2O2) injection and the initiation of in-situ combustion (ISC). The key advantage of the proposed technology is the ability to initiate high-temperature oil oxidation without surface air injection, as the required oxygen is generated directly within the reservoir through the decomposition of the injected H2O2.The study included a comparative evaluation of the catalytic activity of iron oxide (Fe2O3) and manganese oxide (MnO2) nanoparticles, as well as an aqueous potassium permanganate (KMnO4) solution for initiating the peroxide decomposition reaction in the reservoir. It was found that under reservoir conditions, the aqueous KMnO4 solution undergoes reduction upon interaction with high-molecular-weight oil components, forming a solid MnO2 phase, thereby becoming immobilized in the pore space and preventing catalyst washout. As a result, the catalytically active layer forms predominantly in oil-saturated zones, localizing heat release during H2O2 decomposition and preventing non-target consumption of the reagent. In laboratory experiments, a maximum temperature of 336°C was achieved, and gas chromatography analysis confirmed the formation of components characteristic of complete oxidation processes, indicating successful ISC initiation. Numerical simulations performed using the CMG STARS software package confirmed the experimental findings, demonstrating that H2O2 decomposition initiates ISC through a sequence of processes: an exothermic peroxide decomposition reaction with significant oxygen release, followed by oil oxidation transitioning into a high-temperature regime with the formation of a stable combustion front. The model accurately reproduces the temperature profiles and gas composition dynamics, allowing the use of obtained kinetic parameters for predictive simulations and optimization of operational parameters.The implementation of a stable oxidation front driven by oxygen generated from H2O2 decomposition without air injection has been demonstrated. The investigated method represents a promising solution for initiating and maintaining ISC, eliminating the need for complex and costly surface equipment for air or oxygen injection into the reservoir.
This review examines the historical background and current state of enhanced oil recovery (EOR) using surfactant injection in depleted oil fields in Russia and around the world. Current trends and prospects for the development of this method are discussed. Historical accuracy is emphasized: not all surfactant flooding projects during the Soviet period were failures, as is commonly believed by modern researchers. Along with significant miscalculations, there were also some significant achievements. The review discusses the methodological foundations of surfactant screening, the scientific basis for selecting and optimizing surfactant compositions, and the role and mechanism of action of the main components. It also focuses on research related to the injection of surfactant compositions into oil reservoirs. Advances in the synthesis of surfactants used for EOR are described. Particular attention is given to the results of pilot tests and the effects achieved. It is shown that, given the current level of technological development in Russia and the current tax regime, the use of surfactant flooding is unprofitable. At the same time, the injection of surfactant rims and their combination with injection well slurries is successfully developing and is an effective tool for enhancing oil recovery in brownfield areas.
The problem of forecasting the results of geological exploration at various stages is very relevant in the development of licensed areas. According to the authors, it can be solved through the technology of probabilistic assessment of localized resources and reserves, taking into account the probabilities of the field existence. The purpose of the study is to increase the reliability of such estimates based on a geostatistical approach to interpreting data from modern methods of geological investigation. To achieve this goal, two scientific tasks were solved: the task of estimating the probability of the existence of a field (Pg) at the evaluation stage, and the task of estimating the probability of the existence of a field at the point of the exploration well (Pe) at the exploration stage. The article uses model data to show that the key components of Pg – the probabilities of the existence of a reservoir and a seal within the trap – can be estimated based on the results of their seismic prediction: final maps and maps of the standard deviation of the discrepancies. The probability of the existence of structural traps can be obtained from stochastic modeling of structural surfaces, and the probability of their filling – from basin modeling. The Pe components – the probability of a reservoir existence at the point of the exploration well and the probability of a reservoir top to be above the product-water contact also can be obtained from the results of seismic forecasting. The main advantage of the proposed approach is an objective quantitative assessment of the probability of the field’s existence, based on modern research technologies and the degree of study of objects. The main problem is the degree of reliability of the estimation of statistical parameters of the general population according to the sample data. Although the first results of its solution look encouraging, research in this direction needs to be continued.
This paper systematizes the results achieved by BelNIPIneft specialists in the application of digital core technologies to the study of reservoir rocks in the Pripyat Trough. It presents information on the equipment used, research methods, and verification of the obtained results, as well as practical experience in the application of tomographic research results and digital core models to reservoir formations at oil fields in the Republic of Belarus. The paper presents the developed method for digital core analysis, a data sheet, and the results of scaling the number of digital core models to expand the representative range of reservoir properties. The paper briefly describes the results of using digital rock models in hydrodynamic modeling of reservoir development represented by terrigenous sediments and studies to determine the distribution of residual oil saturation after waterflooding in carbonate reservoirs at oil fields in the Republic of Belarus.
The article examines the dynamics of primary energy production in the period from 1970 to 2024. The significance of various types of fuels and energy in this time period is also being assessed. Despite the growing production of alternative energy sources such as wind, solar, geothermal and biofuels, which accounted for 3.6% of the total global fuel and energy mix in 2024, fossil fuels still remain predominant. In the same year, its share was 88.8%. In recent years, there has been a steady increase in the production of alternative energy sources. If current trends continue, their share may increase significantly by 2036, reaching 13%. All types of fossil fuels are also showing steady growth in production. However, the most significant of them is oil, which in 2024 accounted for 35.1% of the total global fuel and energy balance. The US experience over the past 20 years clearly demonstrates that a reduction in conventional oil production can be significantly offset by shale oil and liquefied petroleum gases.
The development challenges of carbonate reservoirs in the Volga-Ural petroleum province are associated with their geological features (presence of fracturing, high formation water salinity, high oil viscosity, hydrophobic rock surface properties). While global practice employs well-established gas and physicochemical methods, Russia practically doesn’t apply conventional EOR techniques in carbonate reservoirs. The article emphasizes that the main methods of carbonate formation stimulation in the Volga-Ural petroleum province include: injection profile conformance technologies (small-scale EOR) as well as production well stimulation through acid treatments. A comparative analysis of literature is provided, reflecting the main types of implemented geological and technical measures. The authors describe in detail their developed individual elements of systemic technology adapted for carbonate reservoirs, optimized for each type of impact based on the industry’s achieved technical level – thereby demonstrating that all geological and technical measures for carbonate reservoirs have been refined and their effectiveness proven. The systematic approach to injection and production well treatments requires multiple expansions and replication, which should lead to profitable reserve recovery in carbonate reservoirs when applying best practices of geological and technical operations.
The article examines a methology for calculating the volume of territories with dredge tailings formed as a result of alluvial deposits mining in the Russian Far East, using remote sensing data. The study considers the application of digital elevation models SRTM, ASTER, ALOS, Copernicus, FABDEM and GEDTM. The modified algorithm of Voronoi diagram construction was used for segmentation of territories with dredge dumps, which allows to increase the accuracy of calculations in conditions of considerable length and heterogeneity of relief. A comparative analysis of the result of volume calculation was conducted for two sites – near the village of Briakan (Khabarovsk Krai) and Dzhalinda River (Amur Oblast) – with and without taking into account the height of vegetation cover was carried out.The study identifies limitations of application of different digital elevation models and ways to improve the accuracy of estimation of the volume of territories with dredge tailings were proposed, which is important both for the assessment of environmental impact and for planning of potential recycling of anthropogenic formations.
Organic-rich Devonian–Carboniferous deposits from the axial and marginal zones of the Kama–Kinel Trough System were investigated. Conodont data place the upper Famennian interval in the expansa Zone and the lower Tournaisian interval in the duplicata and quadruplicata Zones. Six biofacies were identified, described and illustrated, representing anoxic, dysoxic and relatively oxygenated settings. These biofacies differ in organic-matter content, the abundance and diversity of skeletal remains, the character of microbial buildups, and rock textures, including ichnotextures. The studied sections show frequent alternations of biofacies, from metre-scale to centimetre-scale intervals, with the finest alternation recorded on the trough slope. Three depositional scenarios are proposed, corresponding to three basin states: a fully anoxic basin affected by hydrogen sulphide, a stratified basin with separate oxic and anoxic water layers, and a basin with relatively high oxygen content throughout the water column.
For the first time in the world practice, we have proposed transmitter-receiver systems with toroidal coils for evaluating the electrical resistivity of a cylindrical sample during core drilling. Two locations of the toroidal coils are considered: either in an insulating fiberglass pipe or in a highly conductive non-magnetic metal pipe, both inside a ferromagnetic steel outer core barrel. We have elaborated an algorithm for two-dimensional finite-difference modeling of electrical and magnetic signals from an external circular magnetic harmonic current equivalent to a toroidal coil, with regard to the magnetic permeability of the outer core barrel. Two-dimensional numerical modeling of the real (in-phase) and imaginary (quadrature) parts of the electric field vertical component and the magnetic field tangential component is conducted for typical terrigenous core resistivities. Subsequent to the numerical modeling results, the optimal lengths of the logging-while-coring systems, as well as the operating frequencies and measured signal types have been chosen when the coils are located either in the fiberglass or in non-magnetic metal pipe. Further, we come up with transforms of the measured signals into apparent resistivity values for vertically-variable core samples. Finally, we have worked out criteria for the consistency between the signals measured in thin-layered and equivalent electrically macroanisotropic cores while varying the resistivity contrast and interlayer thickness.
The aim of this work is to characterize rare earth fluorocarbonates, first discovered in carbonaceous shales of the Ishlya graben, and to develop an acceptable genetic model of their formation. Riftogenic formations are represented by interbedding of terrigenous rocks (carbonaceous shales, siltstones, siltstones) with a volcano-plutonic association (gabbrodolerites, basic effusives with a small amount of pyroclastic material). All rocks are metamorphosed under epidote-amphibolite facies conditions (T = similar to 390-490 degrees C, P = similar to 2.5-10 kbar). Bastnaesite-(Ce), hydroxylbastnaesite-(Ce), parisite-(Ce) and synchysite-(Ce) were found in carbonaceous shales, morphologically represented by single xenomorphic segregations, veinlets of various morphologies, microgranular masses in selvages of carbonate and quartz-carbonate veinlets, aggregates filling voids in pyrite crystals and spherulites composed of long-prismatic, needle-shaped crystals. It is shown that the genesis of rare-earth fluorocarbonates is caused by hydrothermal metamorphism with a change in the chemical composition of the fluid (CaCl2 + NaCl -> FeCl2). In this case, the source of CO2 was the oxidation of organic matter in carbonaceous shales, and Ca2+ was the albitization of plagioclase. Based on the analysis of indicator ratios of rare earth elements in fluorocarbonates from different regions of the world, it has been established that the chemistry of the mineral formation environment and the scale of the substance redistribution processes are of great importance during their formation (in the case of their locality, greater diversity in the chemical composition of the resulting rare earth fluorocarbonates should be expected).
Studies were conducted on the morphology of the void space, structural-textural characteristics, composition, and mineral formation conditions of Upper Cretaceous (Turonian– Santonian stages) carbonate-clay-siliceous zeolite-bearing rocks exploited at the Tatarsko-Shatrashanskoye deposit. The deposit is located in the northern part of the Ulyanovsk-Saratov Depression. The objects of study were zeolite-bearing siliceous marls from the first bed (t-1) of the productive sequence. A total of 40 samples represented by calcined and uncalcined coarsegrained fractions (0.5–1 mm) were examined.The research was performed using X-ray microtomography (micro-CT) and scanning electron microscopy with energydispersive spectroscopy.The samples are represented by intergrowths of mineral aggregates and detritus, forming medium-, fine-, and very fine-grained, biogenic, scaly, and lepispheric microstructures. The microcomponent composition includes: a paragenesis of authigenic minerals (Opal-CT, the clinoptilolite-Ca – heulandite-Ca isomorphous series, glauconite, clay minerals, volcanic glasses), defined as “camouflaged pyroclastics”; allothigenic minerals (manganoilmenite, zircon); and fossilized remains of calcareous and siliceous biota (foraminifera, coccolithophores, rhabdoliths, diatoms, stomatocysts).Calcined and uncalcined samples exhibit similarity in all characteristics, except for secondary cracks and a rounded surface in calcined samples. The morphology of the primary void space is represented by rounded and elongated biovoids (>1 µm) and tortuous intergranular pores (<1 µm), of open and closed types. By size, pore types are divided into mesopores (<25 nm) and macropores (>25 nm), with the latter predominating.The basis for the unique sorption properties of the zeolitebearing rocks exploited at the Tatarsko-Shatrashanskoye deposit, used in various economic sectors, is their mineral composition in combination with macro- and mesoporosity, and the isomorphism within the clinoptilolite-Ca – heulanditeCa series, which enhances bioorganic sorption.The formation of the zeolite-bearing rocks is the result of the interaction of endogenous and exogenous processes under the conditions of a stable shelf basin with a developed carbonate buffer system.
This study examines the impact of formation water mineralization-a key determinant of wettability boundary conditions-on oil recovery efficiency in natural terrigenous reservoir rocks exhibiting diverse filtration and storage properties. The investigation focuses on sandstone samples obtained from three hydrocarbon fields (Ashalchinskoye, Vostochno-Birlinskoye, and Zuyevskoye) located in the Republic of Tatarstan and Ulyanovsk region, employing advanced digital rock physics techniques through X-ray microtomography-based reconstruction of pore-scale models. The research establishes that the incremental oil recovery achieved through rock hydrophilization via controlled water salinity modification demonstrates strong dependence on the sample's filtration characteristics, with enhanced permeability correlating directly with more pronounced positive effects from wettability alteration. A distinct linear relationship emerges between the magnitude of oil recovery improvement and the permeability coefficient, revealing that reservoirs with superior flow capacity exhibit greater responsiveness to salinity-engineered wettability modification. These findings provide critical quantitative insights for optimizing waterflooding performance in terrigenous reservoirs through strategic manipulation of injection water chemistry, particularly for the studied fields in the Volga-Urals petroleum province, while establishing a fundamental relationship between petrophysical properties and recovery enhancement potential through salinity-controlled wettability alteration.
An analysis of the transformation of the production structure and current recoverable oil and gas reserves in the Khanty-Mansi Autonomous Okrug-Yugra and the Yamalo-Nenets Autonomous Okrug over the tenyear period of the Oil and Combustible Gas Reserves and Resources Classification (Russia, 2013) was conducted. The initial data were based on the State balance of mineral reserves of the Russian Federation as of January 1, 2025. The article provides a detailed examination of reserve dynamics by categories A, B1, B2, C1, and C2, broken down by the main stratigraphic complexes, separately for giant fields and the remaining reserves. It was established that the main oil and gas complexes (the Neocomian in the Khanty-Mansi Autonomous Okrug-Yugra and the Cenomanian in the Yamalo-Nenets Autonomous Okrug) have entered a phase of irreversible depletion: the decline in production is not offset by an increase in production drilling. An increase in the highest category A reserves was identified, while annual production declined, indicating the accumulation of "non-production" reserves due to high water cut and low flow rates. The development of hard-to-recover reserves in the Achimov formation and Middle-Lower Jurassic deposits does not compensate for the loss in volumes. It is proposed to improve the classification by dividing category A into subcategories Ap (operating) and Ap (non-production) to more accurately account for the status of wells.
Seismic instrumentation is becoming increasingly diverse. A major milestone has been the emergence of fiber-optic recording systems based on the capability to measure the time-varying strain of an optical fiber cable. The technology is now well developed and available as commercial solutions. The broad class of fiberoptic recorders referred to as DAS (Distributed Acoustic Sensor (Sensing)) includes several operating principles for working with optical fiber, and not all of them can be applied effectively in seismic exploration. In some cases, it is difficult to identify the technical type of the equipment, especially for new developments. In this paper, we demonstrate an example of equipment testing on a physical laboratory bench that could indicate whether the instrument is suitable; however, field tests reveal that the hardware solution is not appropriate for seismic exploration tasks. We emphasize the importance of field validation of equipment prior to deployment and demonstrate the inapplicability of “amplitude” DAS for seismic exploration applications.
The article presents the results of a study of the material composition of psammite sediments located near the Thoroughbred creek on Askold Island (the Great Peter Bay, Sea of Japan). The sediments are stacked (in wt.%) quartz 58, microcline 14, orthoclase 9, albite 10, kaolinite 5 and amphiboles (actinolite, hornblende) 2, which is close to the composition of the bedrock (biotite-hornblende granites and plagiogranites). The bedrock located next to the sediments. The different granulation of the grains (for example, quartz) indicates a mixed genesis of the sands (alluvial-deluvial). And the partial development of these sediments for gold allows them to be classified as technogenic. The material composition of psammite sediments corresponds to arkose sands. The nature of the behavior of rare earth and trace elements in them indicates the weathering of granites in a humid environment with the formation of a small number of new stable minerals in the form of kaolinite. There is also an enrichment of Ti, U, Pb, Zr and Hf in arkose sands, compared with granites. The presence of ilmenite, zircon and metaothenite control the enrichment of the above elements. Arkose sands are characterized as essentially quartz lithogenic rocks formed in the passive margin. The heavy fraction is about 4 wt.% psammite material. It contains hematite, magnetite, ilmenite, titanite, zircon, monazite, xenotime, metaothenite and gold. The main share is accounted for by iron and titanium minerals. Conditioned contents were found only for gold (0.5 g/t), elevated contents ‒ for silver (0.5 g/ t) and titanium oxide (0.9 wt.%). Gold is present only in its native form. The maximum particle size reaches 750 microns. The particles contain impurities of silver, iron, copper and tantalum. The content of gold itself in the particles varies from 82.7 to 100 wt.%. The studied sediments may be of interest to the construction industry (in addition to raw materials for gold), since the sediments contain a lot of silica (more than 80 wt.%) and few harmful impurities.
