Introduction. In the field of sampling and hydrodynamics of multiphase flows of reservoir fluids, there is a discrepancy between educational and regulatory approaches to the definition of terms and the actual practice of their application. This creates barriers to the perception of information by novice specialists and uncertainty in professional communication.

Goal. The purpose of this work is to develop a consistent terminological system for describing multiphase flows.

Materials and methods. The methods of expert questioning and thought experiment were used in the formation of the terminological system.

Results. A consistent terminological system is presented, which makes it possible to describe modern concepts of the hydrodynamics of multiphase flows.

Conclusion. It is recommended to use the proposals in the formation of normative and methodological documentation and training materials in the field of sampling and hydrodynamics of multiphase flows.

Introduction. Seismic inversion corresponds to ill-posed problems with multiple solutions, e.g. suitable geological models. To evaluate it, data regularization is required, i.e. adding more information in the input data to obtain evaluation criteria.

Aim. The main aim of project is testing & approbation of different regularization algorithms of more appropriate elastic properties evaluation & saturation forecast, depending on input seismic data as well as geological properties.

Materials and methods. Prior to regularization realization during inversion, an experiment based on synthetic model having different noise level and thicknesses & frequencies was provided in order to choose an appropriate regularization algorithm. To check the assumptions made on synthetic model, different regularization algorithms were tested on real data — case studies from Eastern Siberian and Northern Sea oil & gas fields.

Results. Upon the experiment a matrix of solutions was suggested in terms of appropriate regularization algorithm usage depending on input seismic & geology data. Qualitatively, porosity estimation accuracy upon regularization seems to be about 10-15% higher than base case inversion. Furthermore, regularization of simultaneous inversion results allows identification of possible hydrocarbon-saturated zones at more appropriate level.

Conclusion. Case studies from Eastern Siberian and Northern Sea oil & gas fields have shown that regularized inversion allows obtaining more geologically-justified trends in terms of porosity modeling as well as possible hydrocarbon-saturated zones identification by Poisson’s ratio anomalies. This fact leads to risks decrease during reserves estimation.

Introduction. The spectral decomposition technique and the associated RGB visualization algorithm are widely used in many projects for mapping geological objects.

Goal. The aim of the research is to create and test a new technology for automatic frequency selection for RGB blending of spectral decomposition results, as well as to develop a methodology for estimation the quality of the result.

Materials and methods. To test the proposed approach, real data from one of the deposits in Western Siberia were used. The algorithm development and performed using the Python programming language.

Results. As a result of the conducted research, a new approach to the selection of frequencies for the implementation of spectral decomposition and subsequent RGB visualization is proposed. The Shannon entropy estimation is proposed as a tool for estimation of the obtained result.

Conclusion. The developed algorithm has shown its effectiveness on real examples; the resulting color mixing maps are more informative compared to empirical selection.

The paper presents a summary of the experience of using geomechanical modeling to solve problems of field development in terms of studying and reproducing actual events at wells associated with early flooding of deposits due to the failure of the reservoir and shale breaks. The method of estimating changes in elasticstrength properties is considered on the core for various types of reservoirs in Western and Eastern Siberia when changing the saturating fluid to water. The developed modeling graph, taking into account the influence of changes in the elastic-strength properties of rocks from changes in saturation on the destruction of the reservoir and the appearance of highly conductive channels, is applied to gas and oil deposits. The results obtained indicate the relevance of conducting such studies to predict possible negative geomechanical effects on deposits prone to the formation of highly conductive channels from the aquifer or injection wells flooding.

The aim. Study of negative geomechanical effects associated with early flooding of producing wells due to the destruction of the reservoir and shale breaks. Materials and methods. Based on the analysis of available modeling approaches and standard data sets used for geomechanical modeling, calibration methods, an algorithm for reproducing geomechanical effects associated with changes in the elastic-strength properties of rocks from saturation has been developed and tested, which allows taking into account the effect of rock failure on permeability.

Results. According to the results of the conducted studies, it was possible to show the formation of negative geomechanical effects on wells (premature water breakthroughs and the waterflooding from the aquifer).

Conclusion. At different initial core base saturations, studies of changes in the elastic-strength properties of rocks with a change in saturation have been carried out. Studies have shown a significant (up to 10 times) weakening of strength properties in unconsolidated formations when changing natural saturation to water. The created methodology for studying filtration-significant geomechanical effects is used to confirm the actual events at wells associated with the formation of highly conductive channels.

Introduction. This paper considers the issues of history matching process based on different conceptual geological reservoir models of the East-Messoyakhskoe field. The specific feature of considered deposits, associated with Srednemessoyakhskiy swell (graben area) is high well spacing density, and therefore, the different realizations of geological models are comparable with each other when using different modeling algorithms/approaches. The assessment of gas reserves in the gas cap based on well operation process differs significantly from the reserves in the geological model (in all realizations). The problem is complicated by small number of hydrodynamic studies.

Aim. It is necessary to improve the geological model relying on well log and production data sets.

Materials and methods. The history matching process is presented in iterative way. The iterative approach is based on the analysis of well sections, paleo-thickness maps, seismic attributes, facies analysis.

Results. The presence of lateral barriers (tectonic and lithological factors) was identified based on reservoir simulation results. The geological sections of the studied deposits associated with Early Cretaceous age (berriasian-valanginian) is represented not just by a series of bedding layers, but by an alteration of bodies of various scales, extensions with different poro-perm properties. The sand bodies can be differentiated by shale layers or layers with low net to gross ratio — so these zones will be disconnected. Based on the conducted research, the following studies were recommended: gas cap energy state monitoring using piezometric wells, pressure build up logging, reservoir pressure determination, performing pressure interference test.

Conclusion. With high well spacing density the different realizations of geological models are comparable with each other. However, despite of high degree of geological and geophysical knowledge, the history matching results indicate a more complex geological structure. This is a reason for revising the geological settings. There are disconnected zones that are partially visible on seismic data, but they can be confirmed by well testing data, reservoir energy state, different levels of gas-oil-water contacts and caused by sedimentary environment.

Introduction. The article discusses the results of actual operation of horizontal wells with multi-zone hydraulic fracturing (MSHF) in the Bazhenov formation. Drilling and commissioning of wells is carried out as part of a technological experiment to find the optimal technology for developing the Bazhenov formation. Materials justifying the choice of target stimulation technology are presented.

Aim. Development of optimal technology to ensure cost-effective production of hydrocarbons from the Bazhenov formation.

Materials and methods. Actual field data on the operation of wells in the Bazhenov formation were used, and methods of hydrodynamic and probabilistic modeling were considered.

Results. The target parameters of a horizontal well for the Bazhenov formation have been determined — length, proppant volume, amount of hydraulic fracturing, flow rate.

Conclusion. The materials were used in designing the development of the Bazhenov formation in the subsoil area under consideration.

Introduction. The paper is a description of the practical implementation of an approach to creating a geological model of the Jurassic strata of a deposit in Western Siberia in order to predict the structure in the undeveloped part of the license area. The authors relied on the previously accumulated experience of creating permanent geological and hydrodynamic models of the Vatinsky, Megionsky, Arigolsky, Yuzhno-Agansky deposits.

Aim. In order to implement the drilling of directional and horizontal wells for production and exploration, a permanent geological and hydrodynamic model is being created that reflects the main characteristics of the object and gives the best result when implemented according to the “predict -fact” principle.

Materials and methods. The authors analyzed previous implementations of geological models of the object and compared with actual experience. As a result, having formed a concept, performed a justification and implemented a geological model with a plicative structure of the OWC of J1(1).

Results. The change in the geological base of the geological and hydrodynamic model made it possible to improve the development model and improve the quality of adaptation, changed the estimate of the resource potential of the area upside, the model was tested for the implementation of a two-bottomhole pilot well, which confirmed the forecast of the model beyond the reservoir contour.

Conclusion. The best practical result made it possible to obtain a model based on alternative, non-classical theories, which indicates the need for further development of science for current production problems.

Background. For industrial oil production from shale oil formations, it is necessary to drill wells with an extended horizontal wellbore (HW) and multi-stage hydraulic fracturing (MHF). During the entire life of the well, the rate of decline in production rates is well described by Arps curves. During the first year of operation, the rate of decline in production varies from 60 to 80%, wells become low-flow and to effectively extract oil from them it is necessary to use artificial extraction methods. The most popular and effective method today is an electric centrifugal pump (ESP), which is used both when operating in continuous mode and when operating in periodic short-term activation mode (PSA), which allows oil to be extracted from wells at flow rates not exceeding several tons per hour. When the ESP operates in the PCA mode, the flow in the well is unsteady, and to optimize operating modes it is necessary to use specialized simulators for modeling multiphase unsteady flow.

Aim. This work is devoted to the analysis and modeling of operating modes of low-flow wells with an extended HW and MHF during artificial lift with an electric submersible pump (ESP). The article provides a comprehensive analysis of the operating modes of wells in the Bazhenov formation with HW and MHF, operating with an ESP. Complications during the operation of ESPs in such wells are shown, associated both with the removal of proppant and with a constant decrease in productivity and an increase in the gas factor, and data on the operation of various types of ESPs in wells of complex design are provided.

Materials and methods. One of the main achievements of the work is the methodology for creating a model of multiphase unsteady flow in a well with an ESP operating in the PSA mode using specialized so` ware. To accurately describe the physical processes, various approaches were used to numerically simulate unsteady multiphase flows in a well with an ESP with a downhole separator. Difficulties that may arise during well operation were considered through the analysis of field data and the results of numerical modeling.

Results. The article demonstrates the process of tuning the unsteady operating modes of two wells with ESP in PSA mode using specialized so` ware based on real field data (multiphase flow meter, pressure gauges, etc.) taking into account the well design, ESP characteristics, additional equipment (valves, separator and etc.) and formation parameters. The model was tuned to actual data, and possible ways to optimize the operating mode were shown. In addition, the work provides an analysis of the sensitivity of fluid properties and well parameters to unsteady flow in the well.

Conclusion. The work analyzed the operation of more than 40 low-flow wells with HW and MHF with ESP in PSA mode. According to the results of the analysis, ESPs in PSA mode can effectively reduce bottomhole pressure to minimum values of 20–30 bar, provided there is a stable fluid level in the annulus. To select the optimal operating mode of the ESP in PSA mode for low-flow wells, it is recommended to use mathematical models of unsteady multiphase flow in wells.

The aim. High hydraulic friction in the tubing can cause premature shutdown of the hydraulic fracturing operation and costly repairs. Sudden changes in hydraulic friction of the fluid may indicate a failure of cross-linker, breaker or other additives, being an important diagnostic factor. Hydraulic fracturing modeling always includes the calculation of friction in the tubing using existing friction maps, which require constant updating. This paper presents the methodology and its implementation in a new engineering tool for friction analysis in “RN-GRID” fracturing simulation software, which makes it possible to reconstruct friction maps from actual hydraulic fracturing data.

Materials and methods. The proposed friction analysis technique requires actual data on flow rate and bottomhole and wellhead pressures. The entire interval of data has to be split into separate intervals of different fracturing fluids and proppants. The solution of the inverse friction model parameters problem yields friction maps of fluids, displacing one another in the wellbore. Each friction map is identified as a power-law dependence on the flow rate.

Results. The method was implemented as a new engineering analysis tool in “RN-GRID” fracturing simulation software. The method was tested on a number of fracturing jobs on vertical and horizontal wells. It successfully restores the parameters of the power-law friction model, returning the expected and reproducible results on 10 and 18 injections in two horizontal wells. The paper also provides limitations of the method and describes how injection plan can be altered to extract more information on hydraulic friction.

Conclusion. A new method of friction analysis makes it possible to identify friction maps of fluids involved in hydraulic fracturing without additional lab research, even while they replace each other in the wellbore during the injection. The friction correction model for the proppant can also be identified. The tool is intended for engineers’ use to update the friction maps of fracturing fluids.

Introduction. The idea that downhole samples can only be taken in anhydrous wells often creates an unfavorable situation when wells with watered products are not even considered candidates for work. Meanwhile, modern equipment and technology of geophysical research and work in wells (GIRS) presents many possibilities for improving the qualitative study of the reservoir by taking downhole samples.

Purpose. The purpose of this work is to review and systematize the technical means available on the market to solve this problem.

Methods. The developed classification is based on the analysis of open sources and expert surveys.

Results. A classification of modern methods and approaches to deep sampling in flooded streams is presented. Specific technical solutions and directions of design thought are analyzed.

Conclusion. It is recommended to use the proposed classification for the selection of technical solutions when performing tasks for sampling reservoir fluids and well testing.

Background. Problems, described in this paper, related to narrow equivalent circulation density (ECD) window which associated with problems such as formation fluid influx, drilling fluid losses, hole stability issues and etc. Another problem could be related to undrillable well conditions. Conventional drilling through undrillable zone in most cases will lead to simultaneous well control and losses. To overcome such well conditions at Severo-Danilovskoe field operator performs several well control operations and cement bridge installations, but in 90% cases it’s unsuccessful.

The aim. To optimize the process of drilling in complex geological conditions at Severo-Danilovskoe field a dynamic pressure drilling technology was introduced. It included specialized equipment, software, and adaptive engineering approach for ECD optimization in narrow mud weight window environment as well as for drilling through undrillable zones.

Materials and methods. An adaptive approach for flexible transition for one DPM technique to another was developed for expected well complexity. For drilling in narrow mud weight window managed pressure drilling (MPD) technique was applied, and for drilling without window — pressurized mud cap drilling technique (PMCD). To overcome unexpected conditions that were met while drilling (abnormal drilling fluid foaming, wellbore ballooning) unconventional well testing performed in order to examine well behavior at different overbalance/ underbalanced conditions.

Results. Application of dynamic pressure control technology and the development of unconventional procedures made it possible to successfully drill a well with undrillable conditions. The implemented set of well tests using DPM equipment made it possible to design the optimal methodology for killing the well and carrying out tripping operations with the drilling BHA and casing string.

Conclusions. Successful experience of application of DPM technology, as well as methods and procedures developed within this project objectives, could be used to simplify the well construction in difficult environment. This approach could reduce the cost of wells with naturally fractured carbonate reservoirs where presented a high risk of conditions together with abnormal foaming of the drilling fluid and wellbore ballooning.

Introduction. Despite the widespread use of automation, digitalization, remote control and monitoring systems, including video monitoring, at various stages of oil and gas projects, technologies from the second half of the last century are still used in some drilling operations. First of all, this applies to the system for monitoring the technological parameters of drilling fluids. In the article, the authors present the main results of the technological project “Flow”, the implementation of which makes it possible to automate this process.

Aim. The purpose of the project is to develop the equipment for continuous monitoring of drilling mud parameters. It will help to reduce drilling risks such as: gas oil and water inflow, unsatisfactory cleaning of the well, contamination of drilling mud and others.

Materials and methods. Analysis of commercial products presented on the market shows, that most of the devices have limited list of registered parameters of drilling mud. Therefore, it cannot fully provide the necessary level of drilling mud control and makes impossible of use remote monitoring mode. In addition, the supply of foreign high-tech products is limited by the sanctions regime.

Results. As part of the project, a significant amount of research was carried out. Scientist hypotheses were verified. The list of measured characteristics is determined and the basic physical principles of measurements, methods and sampling mechanism are experimentally confirmed. The R&D work accepted successfully. Conclusion. Experimental work carried out in operational conditions at drilling rig proves the performance of technology. Mass implementation of this equipment in the Gazprom neft will start in 2024.

Background. The authors highlight two aspects of automation of conceptual facilities design. The technological aspect. The specificity of probabilistic geological and economic evaluations is the high degree of uncertainty of geological and development parameters, which leads to a large number of combinations and is the reason for the generation of more than 10 thousand variants of fluid production profiles. This set is the initial information for performing technological and cost calculations. The probabilistic formulation of the problem eliminates the possibility of manual labor by an engineer for each individual option. Software that implements the technological aspect in the probabilistic formulation of the problem must methodically correspond to the approaches to the early stages of conceptual design, cover all fundamental technological processes and calculations — gathering, treatment and external transport of oil, gas, condensate, calculation of the gas/energy balance. It is also important to ensure high speed of calculations; it should not exceed several seconds per option. There are no ready-made solutions on the global software market, except for the “Arrangment” module developed by the authors of this study [1, 2].

Expert aspect. For the first time, the authors set the task of creating an expert support system for an engineer as a variant of the implementation of artificial intelligence. The target result is that the expert system, based on limited initial data, automatically generates variants of the arrangement concept and generates a calculation task in the technological and cost module “Arrangement”.

Aim. Development of an expert system for automating the conceptual facilities design in express evaluations (screening) and in probabilistic geological and economic evaluations.

Materials and methods. The process of conceptual facilities design is supplemented by the participation of an expert system. The authors have formed an ontological knowledge base sufficient for automatic decisionmaking about the technical rationality/irrationality of options for development concepts — scenarios. In this case, an expert system is a way to implement artificial intelligence, based on modeling the logical decision-making process, with the ability to demonstrate the progress of “thinking” — cause-and-effect relationships leading to making a specific decision

Results. The functionality of the author’s prototype is demonstrated on a model oil case.

Conclusion. Further development of the expert system will allow the engineer to move from the role of a concept developer to the role of an expert reviewing an automatically generated concept.

Introduction. Modeling of sand production process is one of the priority directions in the field of exploitation of well stock complicated by mechanical impurities recovery. Due to the constant shift of the drainage zone in the direction of the drill sump, as well as a significant number of well stock located in the conditions of terrigenous rocks, the problem of mechanical impurities recovery is constantly increasing its relevance. The solution to this problem requires not only the development of a comprehensive strategy for the protection of downhole pumping equipment (DPE), but also effective prediction of the process of mechanical impurities recovery from the reservoir.

Purpose. The purpose of this paper is to review the technologies available in the world experience in predicting the process of mechanical impurities precipitation, as well as a review of ways to protect DPE from this type of complications.

Materials and methods. The materials considered in the article are: the results of modeling of the processes of fluid movement from the reservoir with joint removal of rock debris; the results of bench tests; the results of field data on the operation of the designated well stock.

Results. The world and domestic experience in the field of prediction and protection in the direction of mechanical impurities recovery from the formation was reviewed.

Conclusion. In the process of well operation, in order to improve the quality of the well stock complicated by the recovery of mechanical impurities, it is necessary to carry out timely effective prediction of rock destruction processes, as well as to build a strategy for protection of the DPE, ensuring the integrity of all units.

Introduction. The peculiarities of the construction and operation of energy facilities in the permafrost zone contributed to the development and creation of entire scientific directions in the field of low-temperature metal science. At the stage of field development, a significant number of piles is used in the construction of foundations. Justification of the application and confirmation of the possibility of using electric welded pile pipes without heat treatment in the construction of foundations on permafrost soils will reduce the costs of enterprises.

Aim. The goal of the work was to study changes in the structure and properties in the weld of steel 09G2S of borehole piles during heat treatment after welding with high frequency currents.

Materials and methods. To conduct full-scale tests of mock-ups of tubular piles, 6 tubular metal piles made of 09G2C steel with HT (heat treatment) and without HT were mounted on an open test site. After exposure, the piles were dismantled and measurements of residual stresses, microstresses, tests for determining impact strength at negative temperatures and microstructure analysis were performed.

Results. Studies have shown that there are no significant differences in the distributions of residual stresses, values of microstresses, in the mechanical properties of pipes during uniaxial tensile tests of pipes with and without heat treatment. The difference in the results on the impact strength of the superheating section of the HAZ, pipes with and without heat treatment, may be due to the release brittleness of the first kind. The microstructure of the base metal of the pipe with and without HT is a ferrite-pearlite structure.

Conclusion. It has been established that the heat treatment of pipes after welding has no positive effect on the microstructure and mechanical properties. It is shown that the microstructure of the HAZ weld of steel 09G2C is unstable to embrittlement at negative temperatures of -60 °C. It is necessary to optimize the welding mode with high frequency currents to reduce the effect of embrittlement of the weld metal.

Introduction. During the experimental program setup with natural rock specimen collection, operating company has to face with particular difficulties and technology limitations associated both with equipment and intrinsic rock properties. The necessity of the application of multiscale approach in pore-scale digital simulations of the natural processes is governed by the key objective — provide a representative digital twin of the natural sample of the particular rock class in the context of the hydrocarbon reserves estimation and the investigation of dynamic of the reservoir properties during its development.

Objective. In this research work the main objective is to provide a systematic approach for obtaining adequate and reliable results of rock properties using digital models supplied with appropriate cases. Also perform the research of and pinpoint the nuances of the multiphase hydrodynamics problems solution for the oil-water system using digital simulations and provide sufficient comparison with lab data.

Materials and methods. In this work the modern methods and equipment is applied for data acquisition — computerized micro-CT of the core miniplugs, steady-state core flood tests for two-phase problem, radiography for interfacial tension measurement.

Results. In this work the multiscale digital rock models (MDRM) were constructed based on micro-CT data. In the article the results of the model calibration to experimental data are presented. The results of simulation versus laboratory data are discoursed in multiple problems statement: hydrodynamics of the single-phase and the two-phase flow, as well as the electric field simulation of water saturated rock samples.

Conclusions. Finally, the conclusions drawn about the future outlook of the Digital Core Analysis technology in the context of modern cutting-edge trends applied to the problems of hydrocarbon reserves and recovery factor estimation.