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The article examines the celebration of the 300th anniversary of the annexation of Siberia to Russia in the key East Siberian cities – Krasnoyarsk and Irkutsk – from the standpoint of communication science, local historical memory and historical politics, as a symbolic action designed to impose on local communities a certain set of narratives associated with the concepts of “Siberia”, “Russia” and “accession” as significant factors of local life. The purpose of the study is to analyze the significance for the local urban communities of Krasnoyarsk and Irkutsk of the 300th anniversary of the annexation of Siberia to Russia as an essential act of local historical memory and an element of local historical politics. The methodological basis of this study is the tools of communication science: the celebration of the 300th anniversary of the annexation of Siberia to Russia is seen as a symbolic act of local historical politics, which was intended to impose on local communities a certain narrative (the key concepts of which are “Siberia” and “joining Russia”), and by the effectiveness of the implementation of which one can judge the self-perception of the urban East Siberian population. The study was carried out on the basis of archival materials (some of which are introduced into scientific circulation for the first time), materials of personal origin, local journalism and media materials. It is concluded that despite the active attempts of the regionalists and the local business elite to organize the celebration and communicative design of the anniversary as a symbolic act of local historical memory, the 300th anniversary of the annexation of Siberia as a significant narrative was shared by a very limited number of the population. The budgets of the event turned out to be sharply scarce, the dates were unclear until the last moment, and the preparations were chaotic. Contrary to the traditional interpretation of this event of 1881–1882, the 300th anniversary of Siberia as an attempt to form a local symbol was unsuccessful, which did not prevent interested subjects of socio-political communications (regionals, part of local elites and government officials) from presenting this event as significant for local life, doing this in fact according to the classical canons of historical politics.

The article reconstructs individual characteristics of the subjects of the initial colonization of Siberia and the Far East and episodes of their advance to new lands. The main methodological approach of the research is the principle of historicism, as well as the principle of “activity constitutes”, widespread in psychological science, according to which identical activities and external conditions should give rise to similar worldview systems. On the basis of this premise, the possibility of judgments by analogy is substantiated in relation to the motives and goals of the first colonizers of Siberia based on the materials of the development of the Far East by the Russians. On the basis of materials of personal origin, the author examines the strategies of legitimizing individual actions of the pioneers through forcing the factor of external threat, as well as using the idea of “state good”. The colonialists use these arguments as a justification for their own actions in the east. At the same time, the acts of colonization undertaken by them have an adventurous connotation characterized by actions with a pronounced emotional component of the decisions made. The problems of relations with aborigines are considered separately. It is concluded that the idea of “peaceful peasant colonization”, which has a civilizing significance for the local population is untenable, as well as the conventionality of the transition of the aborigines under the authority of the Moscow government, which is fully realized by the pioneers.

Relevance. The need to determine a reliable pressure distribution field and fluid filtration velocity vectors inside the perforation hole and the reservoir rock surrounding it. Aim. On the basis of numerical finite element modeling of the fluid flow inside the perforation holes and its filtration in the surrounding reservoir rock, to reveal the patterns of pressure distribution and fluid filtration vectors in the perforation hole, on its walls and in the near-wellbore zone. Objects. Near-wellbore zone of a limestone reservoir of one of the oil fields in the south of the Perm Region, including perforations. Methods. Numerical finite element method for calculating the flow and filtration of liquid in the near-wellbore zone, taking into account the geometry of perforation holes. Results. The paper considers the main relationships used in numerical simulation of fluid flow and filtration in the ANSYS finite element modeling software package. The authors have developed the finite element scheme of the near-wellbore zone, including cumulative perforation holes and taking into account their geometric parameters, as well as the fact that inside the holes the fluid flow is modeled in open space using the Navier–Stokes equations, and in the surrounding reservoir rock based on the filtration equations and Darcy's law. Numerical calculations were carried out, on the basis of which the distribution of pressure, flow velocities and fluid filtration inside the holes and in the near-wellbore zone as a whole was obtained. Calculations were made with varying pressure in the well (or pressure drawdown), as well as for different values of reservoir permeability. The calculation results showed that for the actual drawdown values of 10 MPa and the reservoir permeability of 50 mD, the value of pressure change inside the perforation holes will not exceed 0.01 MPa, i.e. it can be assumed that it practically does not change inside the hole. It is noted that the maximum value of the filtration rate corresponds to the top of the perforation holes and then its value decreases as it approaches the borehole wall. It is concluded that in further modeling of the stress-strain state of the near-wellbore zone, taking into account the holes of cumulative perforation on the surface of the holes, it is permissible to set a constant pressure value equal to the pressure in the well, and not logarithmic or any other distribution of it.

Various casing perforation methods are used to ensure a hydrodynamic reservoir-to-well connection. However, perforated wells often do not perform satisfactorily during production. This is largely due to a decrease in the permeability of the near-wellbore formation as a result of casing perforation work. Studies and analysis of existing casing perforation methods have shown the effectiveness of abrasive jet perforation. The paper presents the results of numerical modeling to optimize the layout of slot channels during the abrasive jet perforation (AJP) of terrigenous productive object. Geomechanics analysis of the influence the formation scheme and orientation of the slotted channels in the productive layer during abrasive jet perforation on the permeability of terrigenous reservoirs of the oil fields in the Perm Krai was performed. The disadvantages of widespread methods of exposing perforation are described and the advantages of abrasive jet perforation based on geomechanical modeling are revealed. The calculations carried out on the placement of slotted channels showed that the distance between the systems of slotted channels is not important, since they weakly interact with each other in height with standard schemes. It was established that the best placement scheme for jet slot channels is a system of four slot channels shifted along the length of the well to the height of the slot channel with a phasing of 90°. Comparative calculations of the reservoir permeability of the near-well zone for various perforation methods have been performed.

The article presents the results of analysing geological structure of the Famennian deposits (Devonian) in the Perm Region. Numerical modelling of the distribution of inhomogeneous stress field near the well was performed for the two considered types of perforation. With regard for the geometry of the forming perforation channels, numerical finite element models of near-wellbore zones were created considering slotted and cumulative perforation. It is ascertained that in the course of slotted perforation, conditions are created for a significant restoration of effective stresses and, as a result, restoration of reservoir rock permeability. Stress recovery area lies near the well within a radius equal to the length of the slots, and depends on the drawdown, with its increase, the area decreases. From the assessment of failure areas, it was found that in case of slotted perforation, the reservoir in near-wellbore zone remains stable, and failure zones can appear only at drawdowns of 10 MPa and more. The opposite situation was recorded for cumulative perforation; failure zones near the holes appear even at a drawdown of 2 MPa. In general, the analysis of results of numerical simulation of the stress state for two simulated types of perforation suggests that slotted perforation is more efficient than cumulative perforation. At the same time, the final conclusion could be drawn after determining the patterns of changes in permeability of the considered rocks under the influence of changing effective stresses and performing calculations of well flow rates after making the considered types of perforation channels.

The relevance of the research is caused by the need to take into account the effects of sandstone reservoir rocks deformations and changes in reservoir permeability for predicting oil wells productivity under conditions of varying values of reservoir and bottomhole pressures. The main aim of the research is based on the results of laboratory experiments, to identify relationships of changes in the sandstone reservoir core samples permeability with changes in reservoir and bottomhole pressures and to assess the degree of these effects influence on the oil well productivity. Objects: sandstone reservoir rocks of the oil fields located in the south of the Perm Region. Methods: laboratory research of the core samples permeability using the laboratory equipment at various values of pore pressure and sample compression pressure; numerical simulation of the near-wellbore zone by the finite element method using the basic relationships of the Biot theory of poroelasticity to determine the magnitude of effective stresses and their effect on the reservoir rocks permeability and oil well productivity. Results. The authors have obtained the analytical relationships that describe the change in permeability with a decrease and recover of reservoir and bottomhole pressure, which showed a decrease in the permeability of core samples by 20,6 % with a limiting decrease in pore pressure from 14,5 to 5 MPa. When the pressure is recovered to the initial value, the permeability is restored only by 84,5 %, which indicates a significant role of rocks irreversible plastic deformations. The results of numerical modeling of the effective stresses distribution in the near-wellbore zone showed that in case of creating the maximum bottomhole pressure drawdown of 9,5 MPa the productivity factor decreases by 10 %. If the drawdown is reduced and the bottomhole pressure is recovered, then the productivity factor recovers just to 92 % of the initial value, which again indicates the negative role of plastic deformations of the reservoir rock. If the reservoir pressure drops to 8,5 MPa, then the reducing in the productivity factor is 13 % compared to the maximum value.

Link for citation: Popov S.N., Chernyshov S.E., Krivoshchekov S.N. Comparative analysis of the analytical and numerical methods for calculating the stress-strain state of the near-wellbore zone based on the elastic model taking into account the main structural elements of the well. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 5, рр.94-102. In Rus. The relevance of the research is caused by the scientific interest in calculating the near-wellbore zone stress-strain state to improve the development of oil and gas fields, to predict the casing stability and the safety of the cement stone. The main aim: based on a comparative analysis of the methods of analytical and numerical simulation of stress calculation near a vertical well using an elastic model, determine the distribution of radial and tangential stresses, compare the accuracy of their calculation by different methods and identify the advantages and disadvantages of each of them. Objects: near-wellbore zone of the terrigenous reservoir of the Achimov deposits of one of the fields of the Khanty-Mansiysk autonomous region. Methods: analytical and numerical finite element methods for stress-strain state calculating of the near-wellbore zone, taking into account the main structural elements of the well and using a linear elastic model. Results. The paper considers the analytical relationships used to calculate the radial and tangential stresses in the casing, cement stone and reservoir rock, as well as the equations used in numerical finite element modeling of stresses near a vertical well. The authors have developed a finite element scheme of the near-wellbore zone, including its main structural elements. The paper introduces the results of calculation of the main components of the stress tensor in the structural elements of the well depending on the radial coordinate for the bottom hole pressure of 20, 40 and 60 MPa. The authors carried out the comparative analysis of the stress calculations results by the methods used. It is shown that the largest discrepancy between the analytical and numerical methods was 2 % that corresponds to radial stresses for the calculation option with a bottom hole pressure of 20 MPa. On average, the discrepancies were: for radial stresses – 0,04 %, for tangential stresses – 0,72 %. It is concluded that when using the model of a linearly elastic medium and under boundary conditions in the form of fixing the model in the upper and lower parts along the normal to the surface, and also without taking into account the pressure distribution in the depression funnel of the model, it is sufficient to use the analytical method of calculation. If it is supposed to use combined boundary conditions, a poroelastic model, taking into account viscoplastic deformations, then it is most preferable to use the numerical simulation method.

Introduction/purpose: The development of elastomeric materials based on synthetic polyisoprene (IR) with high green strength is a rather urgent task, because it allows to replace, completely or partially, the main ingredient - natural rubber in responsible rubber products. The aim of the work was an additional increase in the green strength values of IR and rubber mixtures based on it by its modification with high-density polyethylene of PND 277-73. Methods: The main methods of the research of the technological, physicalmechanical and operational properties were used. All tests conformed to ASTM or ISO standards. Rubber compounds were made in the Haake PolyLab rubber mixer. In parallel with the effects of modification, the influence of the mixing temperature on the main properties of IR and NR based elastomeric materials was investigated. Results: It is shown that the increase in the mixing temperature of NR and IR for 20ºC leads to significant changes in the technological properties of rubber compounds (primarily green strength), as well as the physicalmechanical and operational properties of cured rubber. It has been established that a significant increase in the green strength of the rubber compound is achieved by combining IR with 7 mass. % HDPE. Conclusion: The developed polymer composition based on IR and HDPE has a level of green strength of the rubber compound 2 times higher than that of natural rubber, while maintaining the physical-mechanical and operational characteristics of cured rubbers at the level of natural rubber. The polymer composition IR/HDPE 93/7 can be recommended for use in the manufacture of products whose manufacturing technology requires increased green strength of rubber compounds, including largesized and all-metal tires.