Intensive development of the Tyumen region, where the largest West Siberian megabasin is located (the Tyumen groundwater deposit is the largest in Russia), violates the natural state of ecosystems, in particular groundwater, which is the basis of an ecosystem vital to the health of the planet. Currently, the significance of groundwater is often underestimated. Professor Robert Reinecke from Johannes Gutenberg University Mainz emphasizes that groundwater should be considered as a crucial ecosystem. This is because groundwater is a major ecosystem itself, also it plays a critical role in the earth surface. So what is the hydrogeological uniqueness of the groundwater of the Cherkashinsky area in the Tobolsk district of the Tyumen region?

Mineral and thermal groundwater, historically termed "medicinal water," are essential. In the early 20th century, "mineral water" was synonymous with "medicinal water." Today, groundwater is utilized not only as a mineral resource for extracting valuable components like bromine and iodine but also as technical water. Technical water have special requirements. This is due to the need to assess the geochemical compatibility of formation fluids and injected fluids, because forecasting equilibrium can help prevent problems of salt deposition in oil fields. The difficult procedure for determining the compatibility of injected water and formation water complicates the operational use of hydrochemical data, in especially in monitoring calcite precipitate.

The aim of this article is to present the groundwater composition and evaluate the geochemical compatibility of formation fluids and injected fluids in the Cherkashinsky area. Studying this science topic, we mostly used method of atomic-absorption analysis and the geochemical compatibility of formation fluids and injected fluids. This study examines the value of concentration and potential accumulation of micro-components (bromine and iodine) in groundwater, defined by the geological and hydrogeological conditions of this area. Additionally, we have identified a computational method of compatibility of mixed waters based on calcite and gypsum. Also, we showed the dependency of calcium salt solubility in a multi-component mixture on temperature, pressure, and the partial pressure of carbon dioxide.

The aim of this study is to provide a comprehensive description of the underground hydrosphere of the Megionsky oil field. The field is located within the well-studied West Siberian megabasin. According to V. M. Matushevich's classification (1986), the stratigraphy of the Megionsky field is divided into three overlapping hydrogeological basins (Cenozoic, Mesozoic, and Paleozoic). The results of the analysis of the variation in water mineralization, formation pressures, and geothermal gradients with depth have justified the classification of the Megion oil field as a water-bearing system of the elision-type geodynamic origin. The aquifers and water-bearing complexes in the study area extensively utilized for drinking, domestic, and industrial water supply. Additionally, the Aptian-Albian-Cenomanian hydrogeological complex of the Mesozoic basin is also targeted for the disposal of excess associated water. These factors indicate a significant anthropogenic impact on hydrogeological systems. Understanding the hydrogeological features of the underground hydrosphere provides a foundation for designing measures to protect fresh and mineralized groundwater from contamination and depletion.

Interest in the industrial exploitation of hard-to-recover reserves is growing due to the depletion of the major sources of the country's resource base. These resources are presented by long-developed and multi-layered fields. In most cases oil flow rate from wells in these fields do not exceed five tons daily. This situation affects both extraction costs and the operational performance of the deposits. Currently, under the existing technical and economic conditions, further development of these reserves is becoming unprofitable. This is due to the necessity of planning, designing, and implementing complex geological and technological measures, along with interpreting the extensive data obtained from geophysical surveys.

The aim of this study is to optimize oil extraction processes by injecting flow-diverging compositions in the development of complex and low-yield deposits in the West Siberian oil and gas province associated with the Tyumen suite.

To achieve this aim, we summarized experiences from the studied field and similar fields with comparable geological conditions. We also studied the history of operations involving flowdiverging systems in various tectonic and stratigraphic units. Additionally, we conducted a basic interpretation of geophysical study results from similar fields to identify analogues for creating isolation screens By analyzing existing geological and field data, we verified criteria to perform processing by flow-diverging compositions in the studied field.

Based on the analysis of measures for the implementation of physical and chemical methods to increase oil recovery, we defined a list of recommended basic compositions for initial implementation of this method in the geological conditions under consideration. Taking into account the geological and technological parameters of well operation, we developed a targeted program for injecting flow-diverging compositions. This program will help exploit remaining liquid hydrocarbon reserves and establish primary criteria for selecting candidate wells. We concluded that the results obtained can be replicated in similar fields to optimize the development of low-yield deposits of the Tyumen suite.

There is a unique situation for past decades with Western Siberia Tithonian-Barremian deposit’s regional schemes: the clinoform model of their structure is generally accepted in regional oil exploring organizations, and at the same time, there exists inconsistency between this model and scientific interpretations of current biofacilitie’s complex.

Main goal of this work is initialization of public scientific discussion.

Superstitious biots. The Bazhenov bituminous formation is an integral clinoform model part — central basin deep fine-grained sediments (fondothem by Rich). It is proposed to take clinoform strata structure as conceptual basement of paleobiotic analysis to overcome existing discrepancies. West Siberian paleobasin lateral filling led to a constant replacement of its paleogeographic and environmental condition zones. Superstite (endemic) biotic complexes could be controled by ecological niches, sliding in age along with lithological boundaries. The ecological niche for ammonoids could be poorly ventilated normal salinity waters underlying the brackish waters of the halocline protruding beyond the shelf edge. Absolute age criterion. There is a regionally consistent marker — a tufite layer — at the Upper Bazhenov subformation bottom part. Microanalysis of its zircon grains estimated U‒Pb age as 140.2–141.11 million years, which is in good agreement with the clinoform model.

The biofacilities revision might be operated looking for posible coexisting endemic superstite and panboreal (cosmopolitan) ammonites and other stratifying organisms.

The currently accumulated complex of biostratigraphic data does not directly contradict the clinoform model. A working regional scheme of West Siberian Tithonian-Barremian deposits with a developed agreed upon correlation part and with a general biostratigraphic part’s intermediate version might be submitted for consideration of Russin Interdepartmental Stratigraphic Committee.

The main task in the modern development of the oil industry in in each area is creating a rational strategy for the exploration and hydrocarbon production. This strategy ensures an optimal balance between the required production level and explored reserves. In this regard, oil and gas geophysics requirements are constantly increasing. Geological exploration is being reoriented to search for complex oil and gas traps. Importance of the issues related to the uneven lateral distribution of reservoir properties — primarily porosity and permeability of rocks — is increasing. Standard methodological techniques used in seismic studies no longer provide reliable solutions of geological tasks.

This article focuses on testing technology of fracture zone prediction in geological sections and assessing conductivity for fluids of tectonic disturbances at oil and gas fields. The solution of this task will significantly increase the efficiency of pools development concerning oil and gas fields characterized by complicated geological structure. Typically, evaluation of faults and fractures conductivity is accomplished on the basis of geological and production data. Fault conductivity and fracture zone data in explicit form is not used neither in geological modeling nor in hydrodynamic modeling. This study presents an attempt to apply the diffuse seismic wave field to predict fracture zones in the geological environment and the properties of faults at a real site. Modelling was carried out to assess the potential of this approach, confirming the technology's viability. Further, real data was processed and compared with field data. Real data was processed and compared with field data.

Seismic monitoring (4D seismic survey) of developed oil fields is a new direction in seismic survey. It is designed to solve the main task of field development – maintaining production rates while enhancing the oil recovery factor. Seismic monitoring of reservoir systems is series of 3D seismic surveys, spaced in time in order to receive the dynamic image of processes within the reservoir.

This article focuses on this promising direction and based on a real practical example. In 2008, 3D seismic surveys were conducted in aquatorial part of oil and gas condensate field, using the standard methodologies available then. This data formed the basis for the geological and hydrodynamic models of the field. Today, this field is in the stage of deep development of reserves. To assess, forecast, and involvement in development of new promising reservoirs in deeper intervals, a repeated 3D survey with improved observation system parameters was carried out in 2017.

As a result, two sets of data were collected for the same area, nine years apart. This created the prerequisite for evaluating 4D effects on the reservoirs that had been in operation throughout this period. To isolate the expected effects, 2D seismic-geological modeling was performed, and the seismic data were processed using a unified processing schedule. This article presents the results of data processing and analysis. The potential of using repeated 3D seismic surveys in aquatory for field development monitoring is demonstrated.

The hydrogeochemical characterization of groundwater is a crucial aspect of studying the spatial and temporal variations in groundwater resources, which is crucial for water resource utilization and environmental protection. This article presents the hydrogeochemical profile of interpermafrost groundwater of the Middle-Upper Cambrian horizon local aquifer, based on a case study from a deposit in the Sakha Republic (Yakutia). Also, this study analyzes the impact of both natural and anthropogenic factors on the chemical composition of the groundwater

An analysis of the current conditions of development of unique natural gas fields in Western Siberia reveals that these resources are entering the final development phase. This phase is characterized by critically low pressures insufficient to transport gas to the wellhead. At present time, the share of low-pressure gas reserves increases, but techniques and technologies do not provide efficient and cost effective production. The aim of this study is to develop a universal decision to enhance the extraction process of low-pressure natural gas from the depleted Cenomanian production horizon based on commercial introduction a gas ejector. A gas ejector is device in which the total pressure of the gas flow boosts through turbulent mixing with a higher-pressure flow. This necessitates an analysis of three installation options for the ejector: in the production gas well, at the wellhead, and in the gas collection network. A comprehensive analysis has determined the optimal geometric parameters and operating characteristics of the ejector based on numerical calculations. Modelling of the ejector operation process in hydrodynamic simulator was performed and technological indicators of object development were calculated. Additionally, a technical and economic justification for the design solution has been provided, and the most effective placement of the gas ejector in low-pressure gas fields has been selected.

Western Siberia, in addition to its significant oil and gas reserves, also has huge resources of sapropel and peat, which are estimated at 40 % of the world's total. In world practice, there is a positive experience with using drilling and plugging fluids that incorporate sapropel additives in well construction.

The aim of this article is to investigate the impact of sapropel on the properties of drilling and plugging fluids.

To achieve this goal, we conducted laboratory studies using experimental methods to examine the effects of sapropel on the properties of drilling and plugging fluids. Our results indicate that sapropel can serve various roles in drilling fluids. These roles are weighting agent, thickener, corrosion inhibitor, biocide, clay stabilizer, and lubricating additive. We calculated the density of the developed sapropel drilling fluids, plastic viscosity, and fluid loss. Also, we assessed the prospects for using sapropel in production.

The authors believe that the research of sapropels in drilling and well repair in Western Siberia has been studied extremely poorly. This is the reason for the need for further exploration in this area. Based on the the scientific works reviewed and laboratory research, we have developed an effective method for constructing wells under abnormally low reservoir pressure. This method should help to optimize drilling technology in Western Siberia. This is the importance of the practical significance of our article.

The article considers the problem of determining the stress-strain state of the tank wall in the area where it connects with receiving and dispensing pipes (PRP). One of the significant factors influencing the overall stress-strain state of the tank wall, which is a thin shell according to fundamental laws of structural mechanics, is the presence or absence of settlement of the bases and foundations of the structural elements of the tank.

The article uses both classical structural mechanics methods, and existing analytical solutions. In addition to applying numerical methods, particularly the finite element method (FEM), implemented through the ANSYS software package The developed numerical model of the RVSP-20000 tank using the finite element method in ANSYS PC allowed to determine the displacements, deformations, and stresses in the structures in the junction area of the receiving and dispensing pipe and the RVSP tank wall. The numerical calculations revealed. As the numerical calculation in this article using the FEM complex has shown, the PRP, which has a connection with the reservoir at the level of maximum radial displacements of the wall from the hydrostatic pressure of the stored liquid, creates a significantly altered and potentially hazardous stress-strain state in the contact zone. This highlights the necessity of monitoring potential incompatible deformations in the foundations of both the PRP and the reservoir itself, and, if needed, implementing appropriate engineering measures.

At present, it has been established that the ageing process of pipe steel is multistage. The first stage is characterized by the release of carbon atoms from the metal grains. The second stage is determined by the removal of inter-nodal atoms to the grain boundaries. This removal mechanism is related to the diffusion of carbon through the inter-domain space, facilitated by point defects such as vacancies. The most optimistic estimates give an unrealistically long time of the ageing process of steel. Thus the diffusion mechanism remains unclear.

The aim of this study is to construct a mechanism that would adequately describes this phenomenon. The authors believe such a mechanism should be related to point defects (vacancies). The leading method used in this research is theoretical analysis, which has led to the proposal of an effective way of influence of point defects in intergranular corrosion failure of steel is proposed.Under conditions of uphill diffusion in the linear approximation, mass transfer develops slowly and cannot enrich the adjacent grain boundary layers with impurities. The presence of defects makes the diffusion nonlinear.This study considers thermodefects generated by a temperature gradient. Based on changes in the magnetic properties of the samples, conclusions about the formation of the structure with the participation of carbon impurities displaced in the process of hydrogen introduction were made.

The results of this study can be used in the development of methods of increase of service life of pipe steels.