The results of the studies of geochemical and zoning features of water-dissolved gases in the Mesozoic sediments of the junction between the Yenisei-Khatanga and the West Siberian basins are reported. The stage of industrial oil and gas content is more than 3 km thick and involves the depth range from 750 to 4000 m. Waters occurring in the region contain methane, their total gas saturation is 0.3 to 4.6 dm³ /dm³ , and CH₄ content in 88.9 to 95.4 vol. % on average. An increase in the concentrations of carbon dioxide and methane homologues is observed with an increase in the depth, which is accompanied by a regular decrease in the concentrations of methane and nitrogen. In general, waterdissolved gases from the Neocomian and Jurassic reservoirs have similar compositions (С₁ > N₂ > C₂ > C₃ > n-C₄ > i-C₄ > CO₂ > i-C₅ > n-C₅ ). The water-dissolved gases of the AptianAlbian-Cenomanian sediments are distinguished by lower concentrations of methane homologues (С₁ > N₂ > C₂ > CO₂ > C₃ > i-C₄ > n-C₄ > i-C₅ > n-C₅ ), with the total content of heavy hydrocarbons (HHC) equal to 1.44 vol. %. Vertical zoning of the composition of water-dissolved gases is determined by the distribution of hydrocarbon pools in the Jurassic-Cretaceous section. A regular increase in the average values of the factor of enrichment with hydrocarbons (HC) (from 37 to 154) was established, along with a decrease in the ratio of CH₄ /ƩHHC (from 130 to 7), C₂ H₆ /C₃ H₈ (from 41 to 2) and i-C₄ H₁₀/nC₄ H₁₀ (from 2.6 to 0.6) from the Aptian-Albian-Cenomanian reservoirs to the Jurassic ones. The zone with anomalous He concentrations within the range of 0.4–0.9 vol. % was detected in the Neocomian and Middle Jurassic sediments. This zone is localized at the north-western slope of the Messoyakh inclined ridge (the Anomalnaya, Turkovskaya, Pelyatkinskaya and Sredne-Yarovskaya areas). The nature of this anomaly needs further studies.

Currently, the techniques applied for extraction and study of conodonts from siliceous rocks are associated with a number of problems. This makes it difficult to solve many problems in the areas of development of the volcanic and volcanic-sedimentary rocks, where cherts, jaspers, and phtanites are the only sedimentary formations for dating these deposits.
On X-ray computed microtomography it is possible to avoid some problems to obtain not only excellent 3-D images of conodonts, but sections in any direction too, as well as in video formats. It is shown that similar results are successful under the hollows after the dissolution of the conodonts.
There is no problem in application of X-ray microcomputed tomography when conodonts have been already found on the surface or inside of the sample, or if the content of conodonts in the rock is obviously high. In such a case the scanning without preliminary search is ensured. In cases when conodonts are rare and not obvious, it is proposed the following technique of their discovery.
The rock sample is cut into plates. The conodonts are search for on the surface of the plates, moistened with a mixture of glycerin and water under a binocular microscope. If it is necessary (when the rock is opaque), the result is checked by a chemical reaction: 5–10 % hydrochloric acid plus 1–2 crystals of ammonium molybdate are put on the surface of the sample. The appearance of a yellow sediment means the presence of phosphorus, to indicate the probability the detected object to be a conodont. Next, the sample should be washed from acid, its size should be decreased. Then the microtomographic study should be performed.

The article is devoted to the generation and accumulation systems in the territory of the Crimean-Caucasian segment of the Alpine folded system. An area of prolonged and stable sagging in the Mesozoic and Cenozoic – the Azov-Kuban Trough, which is a typical foreland basin – is distinguished within this segment. According to the results of geological and geochemical studies and modelling, depocentres are identified in this area, consolisated in four generative and accumulative hydrocarbon systems: Triassic-Jurassic, Cretaceous, Eocene and Maikop. Chemical-bitumenological, pyrolytic and coal petrology analysis of rock samples were carried out to assess geochemical conditions of oil and gas content in Meso-Cenozoic sediments. The modelling results made it possible to study and model the elements and processes of hydrocarbon systems in the Meso-Cenozoic in the Western Crimean-Caucasian region. It has been established that the extended catagenetic zoning is typical for these areas, which is caused by high rates of sedimentation and sagging, and large thicknesses of oil-bearing sediments in the source of oil formation, accordingly. The degree of organic matter depletion characterized the residual potential of the oil and gas source strata, was investigated. It is important for predicting and assessing the possibility of hydrocarbon generation.

The article presents studies devoted to the practical application of computer X-ray microtomography (micro-CT) in oilfield geology. In particular, the authors give results of using the method for sample defectoscopy before petrophysical studies in order to improve the quality of analyzes. The paper includes an example of assessing the depth of core plugging with drilling fluid; assessing the mineral composition by micro-CT; experimental core studies when modeling the thermal effect on the oil source rocks of the Bazhenov formation. The authors also examine the current state of research in the field of digital petrophysics or digital core. The study is aimed at introducing the micro-CT method into the oilfield process.

Filtration of oil in low-permeable reservoirs is considered. The experimental data of dependence of filtration velocity on pressure gradient are analysed. It is shown that the filtration law in low-permeability reservoirs differs from the linear Darcy’s law and from the non-linear law with an initial pressure gradient. The power law of filtration in low-permeability reservoirs is experimentally substantiated. Models of nonlinear filtration influence on flow rate are proposed. The analysis of influence of nonlinear filtration parameters on flow rate in technogenically modified near-wellbore zone is carried out.

The relationship between the various human activities and seismic activity has become more evident in the last several decades. One of the important domains where such a relationship manifests itself is hydrocarbon fields’ development. South East Tatarstan (Russia) is a region where the link between seismicity and the development of the giant Romashkino hydrocarbon field has been established. The goal of the current study is to conduct the causative analysis between the seismic activity and the development of the Romashkino hydrocarbon field’s Almetyevskaya area which is located in the most seismically active zone of the southeastern Tatarstan.

The paper discusses the influence of wave action on the process of detachment and transport of particles from a porous body by a two-phase filtration flow. When modeling this process, the problem of the influence of the wave field on the force under the action of which the particles are detached from the pore walls is solved. For the first time, a pore-size distribution function is used for its solution. An expression for the critical flow velocity under wave action has been obtained. Critical frequency value of wave action depends on the capillary radius and the smaller the capillary radius is, the higher frequency is needed to enhance the effect of the action. At higher frequency of oscillation the peak of maximum change in the thickness of the sedimentary layer is shifted towards the pores of small radius. To maintain the influence of the wave field on the filtration parameters of the porous medium, the wave action should be carried out at a dynamically changing frequency range to increase the coverage of the effect of as many pores as possible. It is shown that particle transport during wave action increases due to the action of inertial forces, which reduce the influence of forces holding the particles on the pore surface.

This study introduces results of lithological, petrophysical and geochemical investigation of Lower Cretaceous (K₁ ) and Middle Jurassic (J₂ a-b) rocks of East Pre-Caucasian basin.
According to pyrolytic and bituminological studies method of separate determination of kerogen and bitumen concentration been developed. In accordance with this method differentiation of organic matter components in different lithotypes of rocks been described. Also relationship between bitumen and kerogen concentrations been revealed.
The majority of samples have poor to fair organic richness and poor source potential. Kerogen type is commonly presented by type III and stages of maturity characterized by stages PC₃ to MC₃ . Bitumen compounds have low concentrations of asphaltenes and aromatic hydrocarbons and mainly contains light and heavy resins.
Based on petrophysical and geochemical studies a close relationship between the concentration of organic carbon and the weight concentration of potassium nuclides was obtained. This relationship indicates that kerogen in the sediments under consideration is associated with clay minerals, which is also confirmed by the mineral composition of the rocks.

In the southeast of Western Siberia, the most studied are the Upper Jurassic deposits, most of the oil and gas fields being confined to them. However, the probability of discovering new hydrocarbon deposits in the Upper Jurassic horizons is extremely small. Therefore, of great importance is finding new hydrocarbon deposits in less studied deep-lying complexes.
The article considers the development of a criterion for determining the saturation type of the terrigenous reservoirs in the Hettangian-Aalenian deposits in the southeast of the West Siberian sedimentary basin. We use the example of the UstTym megadepression, a large depression located in the central part of the Tomsk region. The Lower and Middle Jurassic sections are represented by the Urman and Togur formations, Salat formation (Peshkov formation is its isochronous analogue) and Tyumen formation, and characterized by the alternation of predominantly sandy (potential reservoirs) and argillaceous-carbonaceous (seals) sequences. In the studied interval, tests were carried out in just a few wells, for which reason the identification of deposits and promising objects is complicated. Determining the type of reservoir saturation will significantly improve the assessment of oil and gas potential.
As a result of interpreting lateral logging sounding data, the geoelectric parameters of the invasion zone and undisturbed formation were reconstructed for the Lower Jurassic and Aalenian deposits. Based on the well logging data interpretation by means of numerical inversion, we obtained the criterion for the saturation type of the reservoirs (Ju11-17) in the Hettangian-Aalenian complex. The boundary resistivity values for the oil-saturated reservoirs vary from 8 to 20 ohm∙m, while for the water-saturated ones they do not exceed 5 ohm∙m.

The article provides materials on the analysis of the chemical composition of silicates and aluminosilicates that make up the differentiated body of the Misaelga complex, which made it possible by calculation methods to restore the thermobaric parameters of crystallization of the melt in the intermediate chamber
The presence of high-temperature (1472 ºC) intratelluric olivine crystals characterizing the process of magma generation in the mantle and olivine crystallizing under the conditions of the intermediate chamber (1050–1183 ºC) has been established. The calculated crystallization temperature of pyroxenes indicates that they crystallized together with olivine from the bulk of the rocks, and the established variations in the P–T parameters (T = 950–1045 ºC, P = 4.0–7.4 kbar) for plagioclase and amphibole complete the quantitative characteristics of high-temperature melt crystallization processes.
It is shown that the calculated Р–Т parameters of the crystallization of the melt that formed the intrusive massif make it possible to classify its ultrabasic horizon as picrite complexes of the second type that we identified earlier.
Modeling of the crystallization process carried out using two models – according to the algorithm of H.D. Nathan and K.K. Van Kirk and the software product KOMAGMAT – made it possible to establish that the most probable mechanism for the formation of a differentiated body of the Misaelga complex was directional crystallization with gravitational deposition of olivine at the initial stages of the formation of the massif.

The evaluation (according to structural and geochemical rock properties ) of the quartzites from the East Sayan quartzite-bearing area as a potential source of quartz raw material for crystalline silicon and optical glass manufacturing can significantly expand the forecast resources of this type of raw materials. The geological structure of the Irkut Formation, productive of highpurity quartzites is specified within the Oka-Urik, Urengenur and Urdagargan quartz-bearing areas; geological, mineralogicalpetrographic and geochemical characteristics of the main quartzite types are given, the main morphological features of productive high-purity quartzite bodies are specified to predict their occurrence at depth. The major factors in the formation of high-purity quartzite bodies include: 1) quartzites are accumulated in the siliceouscarbonate sequence of the Middle Riphean Irkut Formation within a broad but isolated basin; 2) high-purity quartzite bodies are produced as a result of dynamic recrystallization due to the deformation of primary microquartzites resulting from the collision of the Dunzhugar island arc with the Gargan microcontinent margin. Within the western part of the East-Sayan quartz-bearing area, quartzite reserves as a potential source for silicon metallurgy and production of optical glass were estimated as 134 mln tons.

Studies have been carried out to assess the qualitative features of fluids, aimed at identifying the regularities in the differentiation of the properties of naphthides during the formation of hydrocarbon deposits outside anticlinal structures. Due to the exhaustion of hydrocarbon reserves associated with anticlinal traps, the main attention is paid to the composition of fluids confined specifically to non-anticlinal structures – to traps of a combined structure. Physicochemical properties, trace element (TE) composition, phase states of naphthides in deposits affected by hypergenetic or catagenetic processes have been analyzed using specific examples; in regions with a possible additional inflow of hydrocarbons (Romashkino group of fields in the Republic of Tatarstan); in the crystalline basement of sedimentary basins. The results of the analysis make it possible to predict the characteristic features of fluids in traps of various types at certain levels of the processes of oil formation, secondary transformation and destruction of accumulations, mainly due to the tectonic regime of the sedimentary basin. With prolonged lateral migration, at great depths with good isolation from surface weathering agents, light oils, depleted in TE, more often of nickel specialization, are found in lithologically and stratigraphically screened traps, and gas condensate accumulations are possible. At shallow depths with poor regional or local seals, heavy, highly viscous hypergene-transformed oils, natural bitumens with high concentrations of industrially significant metals V, Ni, Co, Mo Cd, U were found in traps of pinch-out zones and various types of trap screening. tectonically-screened traps) with a multiphase filling of traps and, at the same time, the influence and inflow of deep ones, i.e. more catagenically transformed fluids, it is possible to detect light oils of the nickel type or gas condensates enriched with elements of “magmatic emanations” – As, Hg, Al, B, rare earth elements. Oils filling combined traps in the crystalline basement within platform oil and gas basins, as a rule, do not differ in their compositional peculiarities in comparison with oils in overlying or adjacent parts of the sedimentary section.

It is known that one of the main nowadays problems of subsoil use is the depletion of reserves. Every year many researchers pay attention on mining waste as a source of replenishment of the resource base. Disputes on the prospects of processing technogenic raw materials are relevant. The object of research is the technogenic neoplasms, which were the result of dredging and hydraulic processing of placer gold. The paper presents the results of assessing the prospects and places of application of information technologies, in particular, the analysis of Earth remote sensing data in the design and organization of work to involve technogenic placers in operation. It is shown that these technologies are able to increase the efficiency of work and reduce labor costs at the stage of preliminary study of potential development targets.
Possibilities of detailing the infrastructure facilities of the mining and processing complex are considered. It is proposed to use the vegetation index at a non-traditional time for vegetation research in order to isolate coniferous trees on the formed secondary phytocenoses. An area assessment of the technogenic raw materials of the Kerba gold-placer cluster has been carried out. The analysis of the methodological approach based on remote sensing data is carried out. Aspects of natural vegetation restoration in the post-exploitation period are covered. Optimal combinations of raster data channel combinations for the study of the territory within the boundaries of the object under study are proposed.

The study of the influence of technogenesis on the state of surface waters in urbanized areas is one of the most urgent ecological and social problems. For processing and analysis of hydrochemical indicators of surface water bodies of Kazan for the period 2014–2020 the generally accepted stasticial indicators, as well as the methods of multivariate statistics were used. Hydrochemical models were built using the ArcGisMap software package. The data were grouped using the cluster analysis method separately for each hydrological season with the allocation of 6 groups of hydrochemical components in relation to the maximum permissible values. It has been revealed that the minimum technogenic load on the surface waters of the city falls on the spring period. Based on the analysis of the results obtained, an ecological and hydrological assessment of the state of surface waters was carried out. It was showed that the water bodies of Kazan are classified as unfavorable water bodies.