Results of applying acidic hydraulic fracturing with proppant in the Tournaisian-Famennian reserves at the Ozernoe field

The paper is devoted to the efficiency of acidic hydraulic fracturing – the most widespread method of well stimulation for the Tournaisian-Famennian carbonate reserves found in the Ozernoe field. All the operations performed may be divided in two groups: acidic hydraulic fracturing performed by the conventional technology when fracture openness is reached by wall profile following the reaction of acid with rock, and acidic hydraulic fracturing with proppant. At the site investigated 12 operations of proppant fracturing were performed. To assess the results, including comparison with the conventional acidic hydraulic fracturing, the well investigation data were obtained under nonsteady flow before and after the treatment. In doing so, pressure build up curves were processed by standard methods and that of Warren-Root to evaluate fracturing level. Two wells were chosen with similar production profile and formation flow characteristics prior to well intervention, which were explored twice afterwards. The reservoir was classified as porous for both wells in accordance with pressure build up curve. Following acidic hydraulic fracturing in both cases reservoir fracturing was observed with average fracture openness from 10 to 30 µm. However, nine months after the intervention no fracture were found in the well subjected to conventional acidic hydraulic fracturing, with the same formation flow and production characteristics as before the intervention. The well processed by proppant acidic hydraulic fracturing demonstrates fracturing immediately after the intervention and almost two years later, which testifies to the technology efficiency. The conclusions made were confirmed by field data

Development of probabilistic and statistical models for evaluation of the effectiveness of proppant hydraulic fracturing (on example of the Tl-Bb reservoir of the Batyrbayskoe field)

The main factors affecting the efficiency of proppant hydraulic fracturing of Tl-Bb clastic reservoir depending on various parameters are statistically studied. There are 36 hydraulic fracturing treatments pumped from 2008 to 2016 with an average increase in oil production rate of 8.6 tons per day. Probabilistic statistical models were built to determine the parameters that influence the effectiveness of hydraulic fracturing. The average annual increase in oil production is used as a dependent variable; geological, technological and technical parameters are used as independent variables. To determine the degree of impact of parameters wells are divided into two classes of effectiveness: Qo > 8 tons/day (class 1), Qo < 8 tons/day (class 2). For the first class of each parameter individual statistical models are built for prediction and its probability is calculated. For the combined use of individual models complex probability is calculated separately for geological technological and technical indicators. As a result, regression models are built using step-by-step regression analysis. The standard error of the model for geological and technological parameters is 2.0 tons/day and 2.2 tons/day for technical. The joint consideration of geological technological and technical parameters in the regression model reduces the standard error to 1.5 tons/day. It is concluded that a separate description of the processes of hydraulic fracturing allows evaluating the efficiency of hydraulic fracturing in specific geological and technological conditions at the design stage, based on the use of developed individual models. After the hydraulic fracturing performed using the developed models considering technical conditions it is possible to preliminary estimate the effectiveness of hydraulic fracturing. The developed methodology for predicting the efficiency of hydraulic fracturing, performed on the Tl-Bb reservoir, is recommended to be used at other reservoirs of the field after correction of the built models. On the other fields where information for building the probabilistic and statistical models is available, it is necessary to develop new probabilistic and statistical models

Study of oil recovery from reservoirs of different void types with use of multidimensional statistical analysis

Oil recovery laws that take into account distribution of reservoirs with different void types within the same accumulation. Carbonate field data of development of Tournaisian-Famennian oil accumulation was used. For comparison purposes data of development of the field with similar oil properties but reservoir of clastic grain rock and pore type were used. One injector and neighbor producers were used as components of applied production scheme. The type of reservoir within one development object was determined by several studies including pressure build-up curve processed by Warren-Root method. At the first stage correlation coefficients between injection and production of neighbor well were calculated. Calculation was done for different time and with assumption, according to which correlation coefficient is a quantitative measure of interactions between two wells. It is determined that use of correlation coefficient for pore reservoirs is significantly differ to the character of its behavior for fracture reservoir type. Multidimensional mathematical models that characterize flooding and allow determining producer’s rate were obtained with considered void type. Linear discriminant functions are built with considered void type of reservoir. Analysis of those functions determined that replacement of oil by water in clastic and carbonates porous rocks and carbonate naturally fractured reservoirs follow different scenarios

Predicting dynamic formation pressure using artificial intelligence methods

Determining formation pressure in the well extraction zones is a key task in monitoring the development of hydrocarbon fields. Direct measurements of formation pressure require prolonged well shutdowns, resulting in underproduction and the possibility of technical problems with the subsequent start-up of wells. The impossibility of simultaneous shutdown of all wells of the pool makes it difficult to assess the real energy state of the deposit. This article presents research aimed at developing an indirect method for determining the formation pressure without shutting down the wells for investigation, which enables to determine its value at any time. As a mathematical basis, two artificial intelligence methods are used – multidimensional regression analysis and a neural network. The technique based on the construction of multiple regression equations shows sufficient performance, but high sensitivity to the input data. This technique enables to study the process of formation pressure establishment during different periods of deposit development. Its application is expedient in case of regular actual determinations of indicators used as input data. The technique based on the artificial neural network enables to reliably determine formation pressure even with a minimal set of input data and is implemented as a specially designed software product. The relevant task of continuing the research is to evaluate promising prognostic features of artificial intelligence methods for assessing the energy state of deposits in hydrocarbon extraction zones

Development of the methodology for evaluation of possibilities to determine reservoir types based on pressure build-up curves, geological and reservoir properties of the formation (case study of famen deposits of Ozernoe field)

One of the features of geological structure of Famen deposits of Ozernoe field is naturally fractured reservoir zones. Results of hydrodynamic study of wells on unsteady regime that were processed by Warren-Root model show that naturally fractured zones are oriented North-East. In order to prove existence of zones with different reservoirs statistical analysis was performed. Wherein geological and physical reservoir parameters (absolute elevation, thickness, permeability), several parameters of well performance (initial rate, productivity index) and litho-facial analysis (on cores and seismic) were additionally involved. In this paper interval probabilities that belong to naturally fractured and pore types are determined. Average values of varying intervals compared with interval probabilities. Based on that data pair correlation coefficients calculated and regression equations are built taking into account all studying parameters. Correlation between probability values and addition values are shown on graph. Graphs show probability of naturally fractured reservoir existence for different values of geological and technological parameters. To build the optimal forecast model using individual probability generalized probability were calculated. Scheme that reflect its change on the area of the deposit is built. Analysis show that wells belong to cavitation type determined base on pressure build-up curves in accordance with Warren-Root model is proved by obtained reservoir characteristics. The methodology for reservoir type determination has several advantages, can be implemented on the other fields that are similar in terms of geological structure and Oil and Gas province

Reproduction of reservoir pressure by machine learning methods and study of its influence on the cracks formation process in hydraulic fracturing

Hydraulic fracturing is an effective way to stimulate oil production, which is currently widely used in various conditions, including complex carbonate reservoirs. In the conditions of the considered field, hydraulic fracturing leads to a significant differentiation of technological efficiency indicators, which makes it expedient to study in detail the crack formation patterns. For all affected wells, the assessment of the resulting fractures spatial orientation was performed using the developed indirect technique, the reliability of which was confirmed by geophysical methods. In the course of the analysis, it was found that in all cases the fracture is oriented in the direction of the development system element area, which is characterized by the maximum reservoir pressure. At the same time, reservoir pressure values for all wells were determined at one point in time (at the beginning of hydraulic fracturing) using machine learning methods. The reliability of the used machine learning methods is confirmed by high convergence with the actual (historical) reservoir pressures obtained during hydrodynamic studies of wells. The obtained conclusion about the influence of the formation pressure on the patterns of fracturing should be taken into account when planning hydraulic fracturing in the considered conditions

STUDY OF THE FORMATION OF A WELL BOREHOLE ZONE WHEN OPENING CARBONATE RESERVOIRS TAKING INTO ACCOUNT THEIR MINERAL COMPOSITION

The relevance of the research is caused by the significant influence of the permeability of bottomhole zones of productive formations on well productivity. In practice, a decrease in reservoir permeability in bottomhole zones is often caused by the effects accompanying the interaction of the filtrate of process fluids used in the construction and workover of wells. In turn, the study of the features of the interaction of various process fluids and rocks will allow you to effectively plan operations for the construction and repair of wells. The main aim of the research is to study the features of the interaction of process fluids and rocks based on the integrated use of modern laboratory studies of core and field data. Object: bottomhole zones of wells operating a carbonate object of oil field development. The methods: hydrodynamic studies of wells, processed in the KAPPA Workstation software (Saphir module), using the methods of tangential and deterministic pressure moments with an assessment of the state of bottomhole zones; modern methods of laboratory core research, including electron microscopy, X-ray phase analysis, micro-X-ray tomography. The results. When processing the materials of hydrodynamic studies, it was found that the state of the bottomhole zone in 70 % of the wells of the fund is characterized as degraded, and in some wells – to a large extent, which is not typical for carbonate reservoirs. Water-based drilling fluid was used in all wells during formation opening. Studies of core samples from this deposit (at the micro level) made it possible to establish the complex structure of the void space, including the presence of cracks partially healed by clay material. The interaction of clay material with the water base of the drilling fluid is one of the common reasons for the decrease in the permeability of the reservoir in the zone of its contact with the drilling fluid. Similar studies performed in another field with no clay material in the voids demonstrated the effectiveness of the same water-based drilling fluids, which is confirmed by the almost unchanged state of the bottomhole zone after the wells were put into production

Developing features of the near-bottomhole zones in productive formations at fields with high gas saturation of formation oil

The article studies the formation features of the bottomhole zones in productive formations during operation of production wells in the north of the Perm Territory. Their distinctive feature is the high gas saturation of formation oil. The most widely used parameter in Russian and world practice – the skin factor was used as a criterion characterizing the state of the bottomhole zone. Analysis of scientific publications has shown that one of the main problems of applying the skin factor to assess the state of bottomhole zones is the ambiguity of interpretations of its physical meaning and the impossibility of identifying the prevailing factors that form its value. The paper proposes an approach to identifying such factors in the conditions of the fields under consideration, based on multivariate correlation-regression analysis. Choice of this tool is due to the complexity of the processes occurring in the “formation – bottomhole zone – well” system. When describing complex multifactorial processes, the chosen method demonstrates a high degree of reliability. For a large number of wells in the region, significant material was collected and summarized, including the results of determining the skin factor (1102 values) during hydrodynamic investigations, as well as data on the values ​​of various geological and technological indicators, which can probably be statistically related to the value of the skin factor. A series of multidimensional mathematical models has been built; the skin factor was used as a predicted parameter, and data on the values ​​of geological and technological indicators were used as independent indicators. Analysis of the constructed models is a key stage of this study. Set of parameters included in the multidimensional models, sequence of their inclusion and contribution to the total value of the achieved determination coefficient as the main indicator for the performance of the constructed models were studied. It has been established that the main factor influencing the state of the bottomhole zone is oil degassing. Significant differences in the formation features of the skin factor in the terrigenous and carbonate sediments at the fields under consideration have been determined

FEATURES OF DETERMINING FILTRATION PARAMETERS OF COMPLEX CARBONATE RESERVOIRS AT THEIR OPERATION BY HORIZONTAL WELLS

Link for citation: Salnikova O.L., Chernykh I.A., Martyushev D.A., Ponomareva I.N. Features of determining filtration parameters of complex carbonate reservoirs at their operation by horizontal wells. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 5, рр.137-147 In Rus. The relevance of the research is caused by the fact that in the conditions of continuous deterioration in the structure of hydrocarbon reserves, complex technologies for their development are being implemented, based, among other things, on the use of wells of complex design (horizontal wells). The increase in the share of horizontal wells in the total operating stock determines the relevance of the scientific and methodological justification of research technologies that comprehensively take into account the structural features of the reservoir and the geometry of the fluid flow. The most complete volume of geological and field information can be obtained by combining two main types of research – geophysical and hydrodynamic. The problem of data, in fact, of the indirect research methods, should be considered the need to assess the reliability of their results and the lack of approaches to reduce interpretation uncertainties, which is especially important in the conditions of the impossibility of coring in horizontal wells. This article proposes possible directions for solving these problems. The main aim of the study is the scientific substantiation of approaches to research and interpretation of their results, allowing reliably determining the filtration parameters of productive formations during their operation with horizontal wells. Object: complex Tournaisian-Famenian carbonate reservoirs in Perm region, operated by horizontal wells. Methods: geophysical and hydrodynamic studies of wells, laboratory core studies, multivariate statistical modeling. Results. It has been established that geophysical studies (interpretation was made in accordance with the algorithms for vertical wells) do not allow reliably estimating the length of the horizontal section of the wellbore and the filtration properties of the reservoir. It is recommended to determine the filtration properties when interpreting the data of hydrodynamic studies of wells. Algorithms of modern methods of interpretation of hydrodynamic studies, implemented in common software products, allow you to determine a large amount of geological and field data, including a number of parameters specific to horizontal wells. However, this procedure is accompanied by uncertainties, for example, in terms of the choice of interpretation models. The performed multivariate statistical modeling made it possible to substantiate the methodology for reliably determining the filtration properties of the reservoirs under consideration and the approach to reduce uncertainties when choosing interpretation models

The Institutional Foundations of the Digital Economy in the 21st Century/ Elena G. Popkova, Artem Krivtsov, Aleksei V. Bogoviz.

In English.The development of the Digital Economy has been a landmark breakthrough for economic systems in the 21st century, as it opens up opportunities for the full-scale implementation of new digital technologies and the optimization of economic activities. While the conceptual essence and specific features of the digital economy are described in detail in the existing literature, the practical foundations of its formation are poorly studied. In this book, the digital economy is studied from the perspective of neo-institutional economic theory. This allows for the tracking of the process of formation (institutionalization) of the digital economy, determining the basic institutions that are necessary for its formation and that exist in modern economic practice, and analyzing scenarios for the future development of the digital economy in the 21st century.Frontmatter -- Contents -- Digital Economy in the 21 Century: An Introduction to the Institutional Approach -- Part I: The Scientific Concept of the Digital Economy in the 21st Century -- 1 Digital Economy as a Modern Type of Economic System -- 2 “Digitalization”- Overcoming Institutional Barriers -- 3 Development of the Information Technologies Sector in Latvia under Globalization -- 4 The Principles of Functioning and Priorities of Development of the Digital Economy -- 5 Classification of Breakthrough Digital Technologies and the Perspectives of Their Application in Economy -- Part II: The Process of Digital Economy Institutionalization in the 21st Century -- 6 The Essence and Logic of the Process of Sectorial Markets' Digital Transformation -- 7 The Current Tendencies of Economy Digitalization in Developed and Developing Countries -- 8 The Main Stages of the Digital Modernization of Economy -- 9 Implementation of Cluster Initiatives in the Digital Sphere as a Tool of Digital Entrepreneurship's Institutionalization -- 10 Institutions of Support for Digital Entrepreneurship: Special Economic Zones, Innovative Networks and Technological Parks -- Part III: Meso-Level Institutions of the Digital Economy in the 21st Century -- 11 Digitalization of Regional Economy: Problems and Perspectives -- 12 The Institutional Model of the Digital Economy Creation in a Modern Region -- 13 Managing a Modern Region Based on Digital Technologies -- Part IV: Macro-Level Institutions of the Digital Economy in the 21st Century -- 14 State Institutional Regulation of Economy Digital Modernization -- 15 The Role of Financial Institutions in Supporting the Digital Economy -- 16 Digital Economy of the 21st Century: A View from the Positions of Developed and Developing Countries -- Part V: The Global Institutions of the Digital Economy in the 21st Century -- 17 International Trade in the Digital Sphere: Barriers and Prospects for Development -- 18 The Existing and Perspective International Institutions for Supporting Digital Transformation of Economy -- 19 The Scientific and Methodological Approach to Provision and Evaluation of the Digital Economy's Global Competitiveness -- 20 The Strategy of Optimal Development of the Digital Economy: A View from the Positions of Game Theory -- 21 The Institutional Model of Well-Balanced and Sustainable Digital Economy -- 22 The Institutional Mechanism of Managing the Digital Economy's Development -- Part VI: Case Studies of Institutions of the Digital Economy in the 21st Century -- 23 Problems and Prospects of Economic Cooperation Between Russia and Mexico -- 24 Innovative Critical Success Factors for Public - Private Partnerships (PPP) in Infrastructure Projects of Developing Countries. A Case of Zambia -- 25 Prediction Mechanism of the Territorial Socio-Economic Processes in Formation of the Information Systems -- 26 Specific Economic Security Regulations in the Context of Pathological Crises of Digital Transformation of Agricultural Organizations -- Conclusion: Institutional Perspectives of the Digital Economy's Development in the 21st Century -- List of Figures -- List of Tables -- Index.1 online resource (XI, 258 p.)