The Shaim oil and gas bearing region is situated in the central part of the Pre-Ural oil and gas province in the southwest of the Khanty-Mansi Autonomous Okrug and covers the Sovetsky and Kondinsky administrative districts. Oil exploration in the Shaim region began over than fifty years ago; however, studying the geological structure and hydrocarbon potential of this area remains important. Commercial productivity was confirmed in the Upper Jurassic, Middle Jurassic, and pre-Jurassic oil and gas complexes. The exploration of hydrocarbon potential in Pre-Jurassic deposits has a long history. While fields are actively tapping into these deposits, many unresolved and controversial issues persist, and the results of hydrocarbon exploration in Pre-Jurassic rocks are still modest. In the Shaim oil and gas bearing region, commercial reserves of oil and dissolved gas were identified in the upper part of Pre-Jurassic deposits at fourteen fields, including the Ubinskoye, Tolumskoye, Mortymya-Teterevskoye, Danilovskoye, Severo-Danilovskoye, Potanayskoye, Talnikovskoye, and others. This study analyzes core samples from wells that have penetrated productive intervals of the Pre-Jurassic section (Danilovskaya, Severo-Danilovskaya, Zapadno-Kayumovskaya, Srednemulyminskaya, Andreevskaya, Zapadno-Semividovskaya, Potanay-Kartopyinskaya, Mulyminskaya, and other areas).

In processes involved in geology and the development of oil and gas fields, specialists frequently deal with the water mixing of different origins and properties. The issue of how to analyze the water mixing in order to derive useful information for geological studies and field development has always been topical. One analytical tool for this is Ogilvie’s law, which posits that water components mix linearly in the absence of chemical or physicochemical processes in the system. The aim of this article is to explore the possibilities and limitations of applying Ogilvie’s law. One of the research methods was the use of Ogilvie’s law to assess the behavior of water components during their mixing with each other, as well as during the interaction between water components and reservoir rocks, and between water components and dissolved gases. Additional-ly, the author of this article analyzed the literature sources relating to the use of Ogilvie’s law. The results of this study show that the application of Ogilvie’s law allows to identify processes occur-ring within a geofluid system. Specifically, by analyzing the water mixing components, such as chloride— and in some cases, sodium — within reservoir rocks that do not contain halite, it is possible to determine the mixing proportions of the original waters based on their concentrations in the mixed sample. The limitations of using Ogilvie’s law are the similarity of the mixed waters in chemical composition and salinity, as well as low reservoir rocks permeability, since water mix-ing in such reservoirs has low intensity.

The need to study the salinity of reservoir water arose during the drilling of the first wells at the Raduzhny license area, particularly while interpreting the geophysical surveys of the geological section. Since this well is the first one drilled at Raduzhny, there is no existing database to establish the total mineralization of reservoir water along the vertical section. To address this issue, the author of this article used an integrated approach, taking into account data from neigh-boring fields. Geological and geophysical interpretation must consider the specific characteristics of the study area, where the section penetrated by the wells corresponds to a particular geological type. In this instance, the Tazovsky type of geological section includes the Raduzhnoye, Zapolyarnoye, Yamsoveyskoye, and Yaro-Yakhinskoye fields. The author performed an integrated interpretation across the entire section, from the PK1 reservoir to Ach (BT12). To obtain more complete information about the petrophysical properties of the mentioned reservoirs, the article analyzed the interpretation of geophysical data from fields located in close proximity to the Raduzhny area of the Tazovsky section type. The performed complex of geophysical surveys at these fields is consistent with regulatory documents for well drilling. The author selected a method for determining reservoir water salinity to assess the type of reservoir saturation. This method was subsequently applied in the operational interpretation of the first well drilled in the Raduzhny license area.

The article focuses on the critical issue of preserving reservoir properties of productive reservoir during drilling. One method to minimize the negative impact of drilling fluids on the eservoir is the use of colmatants. The study aimed to evaluate the effect of the colmatant of various fractional composition in a biopolymer potassium chloride mud, with a focus on the permeability of core samples from the BS101-2 productive reservoir in the Surgut group of fields. The test muds contained marble chips with varying fraction ratios, chosen based on the Abrams criteria, as well as fractions that were two times larger and two times smaller than the actual pore size of the core samples. The authors conducted experimental studies using a Vinci FDS-350 apparatus unit under conditions that closely resemble reservoir conditions, utilizing a column made up of three core samples. The researchers calculated the permeability recovery for each of the core sample as well as for the entire core column. The results demonstrated good blocking performance of the mud. The mud invasion depth did not exceed 3 cm, which allows recommending this mud for opening productive reservoir followed by hydraulic fracturing or acid treatment.

Water-induced fractures created during water injection can connect injection and production wells. However, the fraction of produced water often increases significantly only after an initially moderate response following breakthrough. We hypothesize that this delayed acceleration is due to time-dependent leakoff through the fracture walls. Suspended solids are deposited and form a filter cake, gradually reducing wall permeability that increases the fraction of injected water delivered to the producing well. Modern leakoff models explicitly relate leakoff to growth of filter cake and the dynamic effects of transverse flow. We formulate a reduced one-dimensional model for an extant fracture that connecting two wells. Poiseuille law describes flow along the fracture for a slot taken into account distributed leakoff proportional to the pressure difference between the fracture and the formation. We introduce fouling as a time-increasing resistance to leakoff, consistent with filter cake and skin formation concepts widely used in fluid losses modeling. The reduced form yields an explicit expression for the fraction of injected water that enters the producing well. This explicit directly correlates to the predicted water-cut at a constant liquid rate. An example for a West Siberian field reproduces a common observation: the water-cut rises from ~30% at breakthrough to >90% within ~3 months without changes in well operating conditions. We also discuss why producing wells act as attractors for the trajectories of slowly propagating injectioninduced fractures due to poroelastic stress perturbations, and why a wellbore can arrest a fracture after intersection. This behavior agrees with fracture – well interaction in the framework of "stophole" fracture mechanics

This article analyzes the utilization of associated petroleum gas at oil fields in Eastern Siberia, which are characterized by complex carbonate cavernous-fractured reservoirs. The importance of this study arises from the fact that many oil fields operate under technological schemes that do not adequately reflect the geological structure of heterogeneous productive reservoirs. As a result, oil reserves are depleted prematurely and water cut increases rapidly. Additionally, the rational utilization of associated gas often receives insufficient attention, particularly in scenarios where there is a lack of gas transportation or processing infrastructure, low matrix permeability, and natural fracturing. The study aims to develop scientifically grounded recommendations for the efficient utilization of APG at Eastern Siberian fields that operate under depletion drive without waterflooding systems due to the complex structure of the void space and the filtration-capacitance properties of carbonate reservoirs of oil and gas deposits. The study shows that current APG utilization methods exhibit limited efficiency in carbonate reservoirs. By examining the geological and physical properties of these reservoirs, the authors were able to justify potential technological solutions. To optimize the APG utilization system, the work evaluated gas reinjection as a means of pressure maintenance agent, taking into account the characteristics of the pore space. This approach can help APG flaring and improve both economic and environmental performance of field development. In conclusion, the article offers recommendations for the placement of injector well placement based on reservoir characteristics, illustrated by an example of Field X. 

The article discusses the potential of using composite materials in the construction of the beam-balanced pumping unit. Traditionally, these constructions are made from steel with high strength and reliability. However, modern requirements for energy efficiency and cost reduction encourage to active search for alternative solutions. One such solution is the use of composite materials with several significant advantages: low density, high specific strength, corrosion resistance, and the ability to withstand aggressive environments. As an optimal solution, the authors of this article suggest hybrid elements — traverse, connecting rod, and beam. These elements are made from composite profiles with metal inserts in the fastening zones and connected using bonded-bolted joints. Use of hybrid elements ensures both reliable connections and the material's opportunity to interact with different physical and mechanical properties. The article particularly focuses on construction features of metal-composite joints and their potential resistance to bending and tensile loads. The authors further enumerate limitations to the use of composites: high cost, sensitivity to temperature effects, and complexity of repairs. Nevertheless, they consider the combination of composite and metal components as a promising line of development that may enhance the efficiency and durability of equipment in the oil production industry. The article serves as a review of the design phase without a detailed calculation section. 

The article examines issues of design justification for engineering solutions related to mechanical safety requirements for a vertical steel tank planned for construction in an area with karst and suffosion hazards. The object of the study is the "base-foundation-tank" system, whose stress–strain state the authors analyzes under local formation of a karst sinkhole. The article performed finite element calculations using SCAD and LIRA-SOFT software for two potential locations of the karst collapse. The study methodology relies on numerical modelling of the stressstrain state of the object, considering the engineering and geological conditions at the construction site, as well as on comparative analysis of results obtained in independent calculation environments. The study found that the stress-strain parameters remain within allowable limits, confirming compliance with bearing capacity and deformation requirements. Differences in results from the alternative software packages vary by up to 3.27% for deformations and up to 13.6% for internal forces. However, these discrepancies do not significantly affect the actual structural behavior. The article proposes criteria for acceptable discrepancies and advocates for the use of at least two independent software packages when justifying designs for structures with a high level of responsibility. 

Corrosion of metal structures represents one of the most serious problems in the oil and gas industry. Its impact is profound. First, corrosion processes cause direct losses, as they often lead to sudden equipment failure. Second, corrosion results in additional economic costs related to repair, equipment replacement, and forced downtime. With increasing requirements for oil production and transportation, corrosion control has become even more critical. This dictates the need to develop new protective materials for metal structures and the application technologies of them. This study focuses on an in-depth analysis of modern developments in protective materials and application technologies for metal structures operating in aggressive environments and under conditions of intensive abrasive wear. The authors of this article identify the most vulnerable components of oil production equipment that are subject to the highest wear rates. The researchers also determines key negative factors, such as high temperature, exposure to hydrogen sulfide, salts, moisture, mechanical friction, and abrasion. The most effective protective materials include tungsten carbide, nitrides and borides of transition metals, particularly titanium. The article pays special attention to application methods of ceramic coating. Methods as high-velocity oxygen fuel spraying (HVOF), physical vapor deposition (PVD), magnetron sputtering, and related processes demonstrate the greatest potential. These methods offer high efficiency, allow precise control of coating properties, and ensure strong adhesion to the substrate.