Actual field data from the Kuakbashskaya area of the Romashkinskoye oil field are used in this paper for analysis of lost circulation problems during well drilling typical of high permeability carbonate reservoirs confined to Upper Frasnian-Lower Famennian and Okskian-Serpukhovian sediments. Lost circulation control treatments are associated with considerable material loss as well as with significant unaccountable losses in oil production due to formation damage, poor quality of casing cementing in difficult wells, and delayed well bringing into operation. In light of the above, improvements in lost circulation control technologies and implementation of innovative cost-beneficial technologies and materials become of utmost importance. Understanding of the conditions that cause circulation losses enables optimization of these processes. The paper presents different conditions resulting in drilling mud losses. In the north-north-eastern part of the Kuakbashskaya area presence of lost circulation zones in Upper Frasnian-Lower Famennian and Okskian-Serpukhovian sediments is attributable to irregular tectonic compartmentalization of the rocks following the plane of fault system in the crystalline basement and associated troughs in the sedimentary cover. An indirect evidence of the above is the presence of calcium-chloride brines in Okskian-Serpukhovian aquifers, which is peculiar to underlying aquifers. Good transmissibility of the structures in this region is also confirmed by prevalence of nitrogen in the composition of water-dissolved gas. Other conditions favorable for development of fracture system are typical of central and southern parts of the Kuakbashskaya area. Here, domination of neotectonic fracturing associated with lithogenesis processes and neotectonic activity is observed. References 1. Problema treshchinnykh kollektorov nefti i gaza i metody ikh izucheniya (The problem of fractured reservoirs of oil and gas and methods for their study): edited by Smekhov E.M., Leningrad: Nedra Publ., 1968, 179 p. 2. Mingazov M.N., Ibragimov R.L., Karimov M.Zh. et al., Specification of geological structure of Kuakbashskiy bank on the basis of a complex of searches (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2007, no. 1, pp. 25–29. 3. Sulin V.A., Gidrogeologiya neftyanykh mestorozhdeniy (Hydrogeology of oil fields), Leningrad: Gostoptekhizdat Publ., 1948, 339 p. 4. Shalin P.A., Mingazov M.N., Khvoronova T.N., Akhmetov N.Z., Analysis of the results of drilling and operating horizontal wells, taking into account the allocation of decompression zones (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2001, no. 2, pp. 44–46.

Currently, Tatneft devotes special attention to studies of unconventional hydrocarbon sources that contain hard-to-recover reserves. Unconventional sources of hard-to-recover reserves comprise cost-intensive and poorly accessible hydrocarbon-bearing formations. In the Republic of Tatarstan, these are Frasnian-Famennian productive Domanic sediments exhibiting low-quality reservoir properties. Domanic sediments are represented by siliceous-argillaceous-carbonate varieties enriched with organic matter and other dissipated oil components. Domanic deposits of Sargaevskian, Semilukskian-Mendymskian, Eletskian, Dankovo-Lebedyanskian, and Zavolzhskian horizons were proved to be oil-bearing. Petroleum potential of Sargaevskian sediments was confirmed within particular areas in the Southeast of the Republic of Tatarstan. The most promising exploration targets within the Sargaevskian horizon are confined to Saraylinskoye, Bondyzhskoye, Pervomaiskoye, Baskrykskoye, and Zychebashskoye fields. The article continues the publication series related to study of petroleum potential of the Domanic sediments of the Volga-Ural petroleum province. The authors consider the issues of identification and extraction of hydrocarbons from potentially oil-bearing intervals of the Sargaevskian horizon associated with Frasnian-Famennian carbonate complex; selection of candidate wells and test intervals; and highlights well stimulation technologies: particularly, hydraulic fracturing and massive acid fracturing. Attempts to investigate Sargaevskian oil genesis in the territory of Tatneft’s activities are undertaken. Laboratory studies (particularly using geochemical methods) of Sargaevskian core samples have indicated that these rocks have low permeability and contain organic matter in excess of 1 %. This meets the criteria established in Provisional Guidelines for Estimation of Oil Reserves in Productive Domanic Sediments and used for ranking of potential production targets to include them to a category of the hard-to-recover. Pilot operations conducted within the Bonduzhskoye field provided the evidence of oil presence in Sargaevskian sediments. However, oil extraction presents many challenges and calls for unconventional approaches, and further studies, which, in turn, affects the economic performance of oil production. Consequently, necessity for continuing detailed research of Sargaevskian sediments is obvious. It will require application of conceptually new, special-purpose methods for identification and development of production targets.

The paper describes a computer-aided approach to generation of multiple oil field development scenarios. Evaluation of production performance and economic efficiency of various development scenarios is performed on proxy models of LAZURIT Workstation. Production enhancement operations comprise vertical and horizontal drilling, sidetracking, recompletion of existing wells, and application of dual-completion production systems. The workflow of generation of multiple development scenarios begins from creation of a field-wide model, which integrates LAZURIT proxy models for individual production targets. Then appropriate production enhancement operations are selected. Step-wise introduction of proposed operations is provided for considering geological, operational, and economic constraints. This stage is followed by ranking of the proposed production enhancement operations by eight criteria and year-wise distribution of the proposed production enhancement operations. Key performance indicators are calculated for the entire field by each development scenario. The results obtained for all generated development scenarios are recorded and stored for further analysis and selection of optimal solutions for long-term investment planning. The workflow terminates once development scenarios for all fields have been generated. The described method has been tested using an integrated LAZURIT proxy model for Abdrakhmanovskaya area of the Romashkinskoye field comprising eight production targets of Leninogorskneft Oil-and Gas Production Department. Production enhancement operations under consideration included vertical and sidetrack drilling as well as recompletion. The paper illustrates three scenario generation modes: regular distribution of operations by years, descending ladder method and the best of 500 scenarios according to cumulative production with random distribution of operations. The created tool for computer-aided generation of development scenarios for mature fields significantly improves production of residual oil reserves. Acknowledgement. The present study has been funded by Russian Ministry of Science and Higher Education within the Federal Targeted Programme for Research and Development in Priority Areas of Advancement of the Russian Scientific and Technological Complex for 2014-2020 under grant agreement No.05.604.21.0253 as of 02 December 2019 for Creation of Long-term Investment Planning Technology for Efficient Development of Oil Fields Based on High Performance Computing and Machine Learning. References 1. Nasybullin A.V., Sattarov Ram.Z., LatifullinF.M. et al., Creation of software tool for long-term investment planning with a view to the effective development of oil fields (In Russ.), Neftjanoe hozjajstvo = Oil Industry, 2019, no. 12, pp. 128–131. 2. Certificate of authorship no. 2009616218 RF, Avtomatizirovannoe rabochee mesto geologa “LAZURIT” (Automated workplace of geologist “LAZURIT”), Authors: Akhmetzyanov R.R., Ibatullin R.R., Latifullin F.M., Nasybullin A.V., Smirnov S.V. 3. Zvezdin E.Ju., MannapovM.I., Nasybullin A.V. et al., Stage-wise optimization of project well pattern using oil reserves evaluation program module (In Russ.), Neftjanoe hozjajstvo = Oil Industry, 2019, no. 7, pp. 28–31. 4. Nasybullin A.V., Latifullin F.M., Razzhivin D.A. et al., Creation and commercial introduction of methods of oil deposits development management on the basis of computer-aided design technologies (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2007, no. 7, pp. 88–91. 5. Latifullin F.M., Sattarov Ram.Z., Sharifullina M.A., Application of lazurit workstation software package for geological and reservoir modeling and well intervention planning for Tatneft’s production assets (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2017, no. 6, pp. 40–43. 6. Sharifullina M.A., Butusov E.V., Development of hierarchical modelling software for reservoir simulation, field management and selection of appropriate well stimulation technologies (In Russ.), Neftyanaya provintsiya, 2017, no. 4, pp. 116–124, URL: http://docs.wixstatic.com/ugd/2e67f9_9c3ae734e23f48b3a6f0ec08ae79e9eb.pdf

Horizontal technologies are widely used in fields with a high degree of depletion of oil reserves. To enter into the active development of hard-to-recover oil reserves, it is necessary to have a more detailed idea of the quality of the reserves involved in the development to justify the most effective reservoir drainage regimes. In the conditions of oil fields of the Republic of Tatarstan, deposits for drilling horizontal wells include deposits of complex geological structure with increased oil viscosity, which may result in low productivity of conventionally vertical wells. The proposed research experience allows us to justify the effective mode of operation of horizontal wells, to increase the oil recovery coefficient, while improving economic development indicators. The paper presents the results of a comparative analysis of the efficiency of non-stationary drainage regime for vertical and horizontal wells, based on the evaluation of the results of spectrophotometric studies to determine the degree of transformation involved in the development of oil. The change in the drainage regime led to a decrease in the value of the light absorption coefficient of the horizontal well oil to a greater extent than for the conditions of the vertical well, which indicates the involvement in the development of untransformed (matrix) oil and an increase in the reservoir coverage factor. It is noted that the change in the drainage regime did not lead to a qualitative change in the asphaltenes of oil deposits for both horizontal and vertical wells. References 1. Khisamov R.S., Effektivnost' vyrabotki trudnoizvlekaemykh zapasov nefti (Efficiency of stranded oil development), Kazan: Fen Publ., 2013, 310 p. 2. Shaydullin R.G., Gus'kov D.V., Fracture formation model in carbonate array 302, reservoir 303 Romashkinskoye oilfield (In Russ.), Georesursy, 2006, V. 21, no. 4, pp. 14–17. 3. Patent RU 2695183 C1, Method for non-stationary collection of liquid from a fracture-porous type collector, Inventors: Gus'kova I.A., Nurgaliev R.Z., Garipova L.I., Khayarova D.R. 4. Yusupova T.N., Ganeeva Yu.M., Romanov G.V., Barskaya E.E., Fiziko-khimicheskie protsessy v produktivnykh neftyanykh plastakh (Physical and chemical processes in the productive oil reservoirs), Moscow: Nauka Publ., 2015, 412 p. 5. Kayukova G.P., Romanov G.V., Lukyanova R.G., Sharipova N.S., Organicheskaya geokhimiya osadochnoy tolshchi i fundamenta territorii Tatarstana (Organic geochemistry of sedimentary strata and basement of the territory of Tatarstan), Moscow: GEOS Publ., 2009, 487 p. 6. Evdokimov I.N., Losev A.P., Vozmozhnosti metodov issledovaniy v sistemakh kontrolya razrabotki neftyanykh mestorozhdeniy (Possibilities of research methods in oilfield development control systems), Moscow: Neft’ I Gas Publ., 2007, 228 p. 7. Ibatullin R.R., Ibragimov N.G., Takhautdinov Sh.F., Khisamov R.S., Uvelichenie nefteotdachi na pozdney stadii razrabotki mestorozhdeniy. Teoriya. Metody. Praktika (Enhanced oil recovery at a late stage of field development. Theory. Methods. Practice), Moscow: Nedra-Biznestsentr Publ., 2004, 292 p. 8. Petrova L.M., Formirovanie sostava ostatochnykh neftey (Residual oil composition), Kazan: Fen Publ., 2008, 204 p.

At the current stage of fields development in Tatarstan, the key approaches to replacement of oil reserves entail bringing into development oil fields and deposits with high content of multicomponent heavy hydrocarbons and enhancing the production from poorly drained reservoirs containing oil reserves with similar characteristics. The present research effort aims to identify oil accumulations in Carboniferous sediments of the Republic of Tatarstan to predict potential production problems under conditions favorable for structural phase transition in oil. Phase transition can occur in case of changes in oil composition and pressure/temperature conditions in the course of field development. In-situ conditions of oil reservoirs confined to Carboniferous sediments (depth of occurrence, reservoir temperature) and physical/chemical properties of hydrocarbons (composition, viscosity, temperature of phase transition) can cause this problem, particularly during cold water injection for reservoir pressure maintenance. The structure of the remaining oil reserves in the Republic of Tatarstan suggests priority of bringing into development of the Carboniferous oil reservoirs. Investigation and understanding of phase behavior of oil components is still a very important and large-scale task. Identification of oil deposits associated with potential production problems due to phase transition will enable economic development of Carboniferous reservoirs. The analysis has covered 162 oil fields in the Republic of Tatarstan, which comprise 766 oil deposits across the entire sedimentary cover. Of these, 76.5% are confined to Carboniferous sediments. The number of Carboniferous reservoirs is almost equally distributed between Tatneft and other oil companies of Tatarstan, with 71% of Tatneft’s assets found on production sites of oil and gas production departments Leninogorskneft, Yamashneft, and Nurlatneft. Results of the analysis have demonstrated that production assets of Tatneft and other Tatarstan oil producers contain reservoirs with potential phase-transition-related production problems. Oil producers whose production targets are at the risk are presented. References 1. Mansoori G.Ali., Phase behavior in petroleum fluids (A detailed descriptive and illustrative account), Encyclopedia of Life Support Systems, 2009, 33 p., URL: https://www.eolss.net/Sample-Chapters/C08/E6-185-03.pdf 2. Kabirova A.Kh., Khusainov V.M., Structural phase transition and necessity to consider this phenomenon in projects of heavy oil fields development (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2018, no. 7, pp. 32–34. 3. Khusainov V.M., Struktura ostatochnykh zapasov Tatarstana. Problemy i perspektivy razrabotki (Structure of residual reserves of Tatarstan. Problems and prospects of development), Collected papers “Trudnoizvlekaemye i netraditsionnye zapasy uglevodorodov: opyt i prognozy” (Hard-to-recover and unconventional hydrocarbon reserves: experiences and forecasts), Proceedings of International scientific and practical conference, Kazan: Fen Publ., 2014, 2014, pp. 86–89. 4. Khamidullin F.F., Amerkhanov I.I., Shaymardanov R.A., Fiziko-khimicheskie svoystva i sostavy plastovykh neftey pri differentsial'nom razgazirovanii na mestorozhdeniyakh Respubliki Tatarstan (Physico-chemical properties and compositions of reservoir oils during differential degassing in the fields of the Republic of Tatarstan), Kazan: Master Layn Publ., 2000, 344 p. 5. Muslimov R.Kh., Abdulmazitov R.G., Khisamov R.B. et al., Neftegazonosnost' Respubliki Tatarstan. Geologiya i razrabotka neftyanykh mestorozhdeniy (Oil and gas bearing of the Republic of Tatarstan. Geology and development of oil fields), Part 1, Kazan': FEN Publ., 2007, 316 p.

Basically each major company repeatedly faces the issue of well completion quality. This is associated with low actual oil flow rates compared to expected production. Accordingly, a strong focus is placed on various drilling technologies, drilling mud formulations and completion tools, including underbalanced drilling. Thus, the purpose of this study is addressing the issue of well drilling and completion quality for the main types of reservoirs, wells, drilling mud and completion technologies applied in Tatnet PJSC. For this purpose, results of pressure build-up tests reflecting the fluid flow in situ were used. Mechanical skin-factor representing the changes in properties of the bottomhole zone or fracture was applied as the main comparison parameter. Results of flow tests performed in 396 wells have demonstrated that the average mechanical skin-factor ranges within 0.1-0.5, which is equivalent to well production decline of 1-5%, on the average. However, a number of wells exhibited better performance or greater formation damage. All this suggests that the problem of well completion quality is not the top priority issue for Tatnet PJSC. The total skin, which also considered well geometry, was about minus 4.0, which is attributable to extensive drilling of horizontal wells, bottomhole zone treatment jobs and hydraulic fracturing operations. For this reason, even negligible adverse effects from well drilling and completion are entirely offset due to the activities mentioned above. However, multiple operations conducted prior to flow tests (drilling, perforation, completion, stimulation) did not allow differentiation of various completion practices for selection of optimal technologies considering individual reservoir properties. References 1. Ibragimov N.G., Iktisanov V.A., Ibatullin R.R., Akhmadishin F.F., Estimation of technological efficiency of formations exposing in drawdown conditions (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2005, no. 4, pp. 108–111. 2. Khuzin R.R., Musin K.M., L'vova I.V., Laboratornoe modelirovanie na kernakh s tsel'yu otsenki vliyaniya na fil'tratsionnye svoystva plasta, primenyaemykh pri pervichnom vskrytii polimernykh burovykh rastvorov (Laboratory core modeling to assess the effect on the reservoir properties of the formation used in the initial opening of polymer drilling fluids), Collected papers “Metody uvelicheniya nefteotdachi trudnoizvlekaemykh zapasov. Problemy i resheniya” (Oil recovery enhancement methods for hard-to-recover reserves. Problems and solutions), Proceedings of NIInefteotdacha RS of RB, 2003, V. 4, pp. 153–159. 3. Ibatullin R.Kh., Khabibullin R.A., Rylov N.I., The technology of well completion in terrigenous sediments (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 1987, no. 2, pp. 21–24. 4. Ovnatanov G.T., Vskrytie i obrabotka plasta (Sompletion and formation treatment), Moscow: Nedra Publ., 1970, 312 p. 5. Muslimov R.Kh., Mokhel' A.N., Kulinich Yu.V., Volkov Yu.A., O mekhanogennykh izmeneniyakh produktivnosti vertikal'nykh, gorizontal'nykh i naklonno-napravlennykh skvazhin (On mechanogenic changes in the productivity of vertical, horizontal and directional wells), Collected papers “Prirodnye rezervuary uglevodorodov i ikh deformatsii v protsesse razrabotki neftyanykh mestorozhdeniy” (Natural reservoirs of hydrocarbons and their deformation during the development of oil fields), Proceedings of All-Russian Scientific Conference, Kazan, 19–23 July 2000, Kazan: Publ. of Kazan University, 2000, 30 p.

Tatneft Company devotes considerable attention to the search and implementation of new technology solutions to enable extension of field economic life by managing fluid production fr om heterogeneous oil-producing reservoirs (structurally complex production zones) through partial or complete shut-off of water production intervals or seal-off of water conductive fractures. For this purpose, water shut-off treatments can be performed to reduce excess production of produced water and hence, decrease (stabilize) wellstream water cut. Excess water production can occur due to a number of different reasons; including different mobility of oil and displacing agent (particularly, water injected to maintain reservoir pressure), geological heterogeneity, presence of high-permeability intervals, which are the primary frontal advance channels. High water cut can also result fr om bottom water coning and inter-reservoir fluid communication between the producing reservoir and adjacent waterflooded or water-saturated intervals due to lack of continuous impermeable barrier in presence of extensive vertical fracture networks or faults. A variety of physical and chemical methods for formation treatment, which has been widely practiced in the oil industry, enable mitigation of adverse effects of these factors on production performance, reduction (stabilization) of wellstream water cut and enhancement of oil production. These improvements can be achieved through treatments of both production and injection wells. This approach has been successfully used in Tatneft Company for development of terrigenous reservoirs. However in carbonate reservoirs, arrangement of efficient reservoir pressure maintenance system is challenging (due to absence of connectivity between injection and production wells and “instantaneous” breakthrough of injected water through well-developed fracture system). In such reservoirs, water shut-off in production wells is often the only way of water cut control. References 1. Kadyrov R.R., Metody ogranicheniya vodopritoka pri stroitel'stve i ekspluatatsii skvazhin (Methods of water shutoff during the construction and operation of wells): thesis of doctor of technical science, Bugul'ma, 2009. 2. Patent no. 2382185 RF, MPK E 21 V 43/22, C 09 K 8/90, Method for injection well infectivity profile aligning and water in-flow limitation for production well (Versions), Inventors: Ibatullin R.R., Amerkhanov M.I., Rakhimova Sh.G., Beregovoy A.N., Zolotukhina V.C., Latypov R.R., Khisamov R.S. 3. Amerkhanov M.I., Beregovoy Ant.N., Rakhimova Sh.G. et al., Razrabotka i opyt primeneniya novykh vysokoprochnykh polimernykh sistem dlya ogranicheniya vodopritoka v dobyvayushchie skvazhiny (Development and experience in the application of new high-strength polymer systems to lim it water inflow into production wells), Collected papers “Innovatsii i tekhnologii v razvedke, dobyche i pererabotke nefti i gaza” (Innovations and technologies in the exploration, production and refining of oil and gas), Proceedings of International scientific and practical conference dedicated to the 60th anniversary of Tatneft OAO, Kazan, 8–10 September 2010, Kazan: Fen Publ., 2010, pp. 19-22. 4. Amerkhanov M.I., Beregovoy Ant.N., Rakhimova Sh.G. et al., Rezul'taty primeneniya tekhnologii ogranicheniya vodopritoka v dobyvayushchie skvazhiny s ispol'zovaniem vysokoprochnykh polimernykh sistem (The results of the application of technology to lim it water inflow into production wells using high-strength polymer systems), Proceedings of TatNIPIneft' / PAO “Tatneft'”, 2012, V. 80, pp. 134–138. 5. Beregovoy Ant. N., Rakhimova Sh.G., Vasil'ev E.P., Afanas'eva O.I., Belov V.I., Razumov A.R., Rezul'taty primeneniya kompleksa tekhnologiy VPSD dlya ogranicheniya vodopritoka v dobyvayushchie skvazhiny (Results of application of high-strength polymer systems for water shut-off), Proceedings of TatNIPIneft' / PAO “Tatneft'”, 2017, V. 85, pp. 264–272. 6. Rakhimova Sh.G., Beregovoy Ant.N., Knyazeva N.A., Andriyanova O.M., A research into effects of water composition on gel formation process and gel stability during on-site preparation of polymer (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2018, no. 7, pp. 28–31. 7. Sachs L., Statistisehe Auswertungsmethoden, Springer-Verlag, Berlini-Heidelberg-New York 1972.

Acidizing is the most common method of oil production stimulation. Its effectiveness depends on many factors. The developed integrated approach includes analyses of the well work deterioration causes and testing of technological compositions under field conditions. Experiments and treatments are carried out under Tatneft PJSC fields conditions. Samples from injection wells were initially analyzed. The presence in bottomhole zone of colmatation substances consisting of iron compounds as iron scale and precipitation of ferric hydroxide, suspended solids as sand and clays particles, hydrocarbons is shown. As a result of the study three technological compositions corresponding to all requirements applicable to reagents of bottomhole zone treatment are selected. The third portion feature of acid treatment is application of sulfamic acid that corresponds with law temperatures of the Romashkinskoe field. The technology developed of cleanup of injection wells bottomhole zone is three-stage well treatment with removal of reaction products. All works are conducted using coil-tubing unit. After treatments the samples are collected. It is confirmed that the iron ions presence is one of the causes of injection wells bottomhole zone colmatation. The high effectiveness of the technology is shown. For the period of the study 200 wells are treated, the success ratio is 85%, the profitability index is 1.2. References 1. Ibragimov L.Kh., Mishchenko I.T., Cheloyants D.K., Intensifikatsiya dobychi nefti (Oil well stimulation), Moscow: Nauka Publ., 2000, 414 p. 2. Silin M.A. et al., Kislotnye obrabotki plastov i metodiki ispytaniya kislotnykh sostavov (Acid formation treatment and methods for acid compositions testing), Moscow: Publ. of Gubkin Russin State University of Oil and Gas, 2011, 120 p. 3. Gus'kova I.A., Analiz faktorov effektivnosti ochistki prizaboynoy zony nagnetatel'nykh skvazhin metodom dinamicheskogo izliva (Analysis of efficiency factors for cleaning the bottom-hole zone of injection wells using the dynamic spout method), Collected papers “Povyshenie nefteotdachi plastov na pozdney stadii razrabotki neftyanykh mestorozhdeniy i kompleksnoe osvoenie vysokovyazkikh neftey i prirodnykh bitumov” (Enhanced oil recovery at a late stage of oil field development and integrated development of high-viscosity oils and natural bitumen), Proceedings of International scientific and practical conference, Kazan': FEN Publ., 2007, pp. 195–197. 4. Glushchenko V.N., Silin M.A., Neftepromyslovaya khimiya (Oilfield chemistry), Part 4. Kislotnaya obrabotka skvazhin (Acid treatment of wells): edited by Mishchenko I.T., Moscow: Interkontakt Nauka Publ., 2010, 703 p. 5. Magadov R.S., Silin M.A., Paevoy E.G., Magadova L.A., Pakhomov M.D., Davletshina L.F., Mishkin A.G., The development of well acidizing using the additive Neftenol K (In Russ.). Neft', Gaz i Biznes, 2007, no. 1–2, pp. 93–97 6. Silin M.A., Magadova L.A., Davletshina L.F., Efanova O.Yu., Research of deep samples out of injection wells carried out with the aim of development of compositions and technologies for treating of a formation bottom area (In Russ.), Neftepromyslovoe delo, 2013, no. 7, pp. 36–40.

Determination of water cut of the fluid recovered from oil-producing wells is an inherent part of the whole field development process. A sampling device (or sampling cock) is used routinely to periodically collect wellhead samples into a receptacle for further measurements of the percent content of oil and water under laboratory conditions. In case of manual sampling, poor accuracy of analysis results obtained with samples from high-watercut wells is attributable to intrinsic disadvantages of this method: recovery of fluid samples only through one sampling point of the pipeline, low sampling rates, and adverse effects of human factor. For these reasons, periodic manual sampling cannot provide reliable data on the actual water content of the wellstream (particularly, in case of high water cut) and impedes timely response to optimize the operations. Hence, implementation of new water cut determination methods for production wells is of utmost importance. The paper considers promising innovative methods for determination of water cut of production wells using a portable on-stream watercut meter. The authors present the results of water cut studies using this watercut meter and the automatic sampler in a production well characterized by wide variations in water cut measurement results obtained for manually collected samples. Best practices in improving the accuracy and decreasing the expenses on water cut measurements are also reviewed. References 1. Vosproizvodstvo mineral'no-syr'evoy bazy, vklyuchayushchee poiski i razvedku novykh mestorozhdeniy neftyanykh i gazovykh iskopaemykh dlya nuzhd narodnogo khozyaystva (The reproduction of the mineral resource base, including the search and exploration of new deposits of oil and gas minerals for the needs of the national economy), URL: http://www.gkz-rf.ru/index.php?option=com_content&view=article&id=229:2015-04-21-07-53-31&catid=53:docsuvs&Itemid=70 2. Patent RU 2453689 C1, Oil deposit development method, Inventors: Khisamov R.S., Khamidullin M.M., Shaydullin R.G., Galimov I.F., Vanyurikhin I.S., Galiev F.A. 3. Chudin V.I., Ushkov P.V., Shatalov V.A., Zhilyaev O.V., O dostovernosti opredeleniya obvodnennosti produktsii, dobytoy iz neftyanoy skvazhiny, po probe (On the reliability of determining the water cut of products extracted from an oil well by sample), Collected papers “Aktual'nye voprosy metrologicheskogo obespecheniya izmereniy, raskhoda i kolichestva zhidkostey i gazov” (Actual issues of metrological support of measurements, flow rate and amount of liquids and gases), Proceedings of III international metrology conference, Kazan': Mir bez granits Publ., 2015, pp. 42–45. 4. Levin K.A., Tonkonog M.I., Chudin V.I. et al., O rezul'tatakh issledovaniy otkloneniya predstavitel'nosti proby, otobrannoy probootbornikami PORT (On the results of studies on the deviation of representativeness of a sample taken by PORT samplers), Collected papers “Aktual'nye voprosy metrologicheskogo obespecheniya izmereniy, raskhoda i kolichestva zhidkostey i gazov” (Actual issues of metrological support of measurements, flow rate and amount of liquids and gases), Proceedings of III international metrology conference, Kazan': Mir bez granits Publ., 2015, pp. 46–47. 5. Chudin V.I., Obvodnennost' – reshenie ee opredeleniya po probe (Water cut – the solution of its determination by sample), Collected papers “Aktual'nye voprosy metrologicheskogo obespecheniya izmereniy, raskhoda i kolichestva zhidkostey i gazov” (Actual issues of metrological support of measurements, flow rate and amount of liquids and gases), Proceedings of II international metrology conference, Kazan': Mir bez granits Publ., 2014, pp. 40–41. 6. Chudin V.I., Ushkov P.V., Nurmukhametov R.R., Beloklokov V.V., Obzor probootbornikov syroy nefti, razrabotannykh v OOO “NPO “NTES” (Overview of Crude Oil Samplers Developed by NTES NPO LLC), Collected papers “Aktual'nye voprosy metrologicheskogo obespecheniya izmereniy, raskhoda i kolichestva zhidkostey i gazov” (Actual issues of metrological support of measurements, flow rate and amount of liquids and gases), Proceedings of I international metrology conference, Kazan': Mir bez granits Publ., 2015, pp.20–23.

The paper considers important issues associated with efficient operation of oilfield equipment and thus, cost-effective operation of production wells. Cost-effectiveness is best described in terms of equipment life cycle and cost estimates over the useful life period with account of durability and non-failure operation time. The major challenge associated with further advancements in oil production equipment has become the “human factor” which may interfere with efficient utilization of available facilities. It should be noted that to-be specialists with comprehensive expertise and in-depth knowledge in “pure’ and “applied” mathematics and IT should have the similar wealth of knowledge in science (physics, mechanics, chemistry, biology etc.) and humanities (discussing dialectical relationships between object properties and tangible world events). Otherwise, operation of production facilities results in generation of cross-functional barriers reducing the deliverability of the system and increasing maintenance costs. As far as oil production progresses, efficiency of the production processes decreases and gradually approaches to performance limits. Eventually any new generation of the main facilities and any future process model provide less performance improvement, while implementation costs remain at the same level. That is, each brand-new or even breakthrough technology has its operational limit and cannot yield more than it has been intended for. At the end stage of operation, improvement of individual engineering solutions may become uneconomic or unfeasible. This indicates reaching the limit of productivity growth for production systems relying on particular operation principle. This creates objective necessity in development of production systems based on new operating principles. Thus, each contemporary oil production enterprise that operates various oil production tools should be considered as an emergent system, which has a multilevel structure with complex interactions between energy, technology, information and geo-information. The present paper resulted from analytical studies based on general patterns of technological development. However, the most important conclusion is that the results of this analytical study are fully confirmed by production process monitoring data obtained by Tatneft Company. References 1. Spath J., Transforming the upsteam service industry to increase operator margins, SPE-0516-0054-JPT, 2016, https://doi.org/10.2118/0516-0054-JPT 2. Yartiev A.F., Khisamov R.S., Akhmetgareev V.V., Innovatsionno-investitsionnoe razvitie neftedobyvayushchey promyshlennosti na osnove realizatsii operatsionno-proizvodstvennykh strategiy v Respublike Tatarstan (Innovative and investment development of the oil industry based on the implementation of operational and production strategies in the Republic of Tatarstan), Kazan': Ikhlas Publ., 2020, 239 p. 3. Antoniadi D.G., On the joint efforts of companies, scientists and specialists in the oil and gas industry to organize the Russian National Institute of Oil and Gas (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2019, no. 10, pp. 46–47. 4. Yartiev A.F., Fattakhov R.B., Uchet energeticheskikh zatrat na dobychu nefti (Accounting for energy costs for oil production), Moscow: Publ. of VNIIOENG, 2007, 149 p. 5. Orlov P.I., Osnovy konstruirovaniya (Design principles), Moscow: Mashinostroenie Publ., 1988, 560 p. 6. Klimov V.A., Valovskiy K.V., Valovskiy V.M., Izuchenie vozmozhnosti povysheniya nadezhnosti glubinnonasosnogo oborudovaniya (na primere nasosnykh shtang) (Studying the possibility of increasing the reliability of deep-pumping equipment (for example, sucker rods)), Collected papers “Tekhnika i tekhnologiya razrabotki neftyanykh mestorozhdeniy” (Technique and technology of oil field development), Proceedings of Scientific and technical conference dedicated to the 60th anniversary of the development of the Romashkinskoye oil field, g. Leninogorsk, 15 August 2008, Moscow: Neftyanoe khozyaystvo Publ., 2008, pp. 200–206. 7. Antoniadi D.G., Savenok O.V., Arutyunyan A.S., Analysis of the possibilities of the improvement of the bore technology and conditions to its exploitation at decision of the problems of increasing to efficiency of oil production with complicated condition (In Russ.), Nauchnyy zhurnal KubGAU, 2013, V. 87, no. 3, pp. 240–259. 8. Klimov V.A., Valovskiy K.V., Valovskiy V.M. et al., On the physics of failures, methods of reliability calculations, and efficient performance of rod string in a well (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2011, no. 7, pp. 66–69. 9. Klimov V.A., Valovskiy V.M., On operational efficiency of sucker rods (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2015, no. 1, pp. 94–97. 10. Vvedenie v matematicheskoe modelirovanie (Introduction to mathematical modeling): edited by Trusov P.V., Moscow: Universitetskaya kniga, Logos Publ., 2007, 440 p. 11. Manokhina N.V., The meta-system as the object of institutional analysis (In Russ.), Vestnik Mezhdunarodnogo instituta ekonomiki i prava, 2014, no. 1 (14), pp. 7-16. 12. Yusupov R.M., Sokolov B.V., Ptushkin A.I. et al., Research problems analysis of artificial objects lifecycle management (In Russ.), Trudy SPIIRAN, 2011 no. 1 (16), pp. 37–109. 13. Etalonnaya arkhitektura intellektual'nykh energosetey (Smart grid reference architecture), URL: http://d2_rus.cigre.ru/doc/SERA_v2_ru_v2.1.pdf. 14. Petrochenkov A.B., Regarding life-cycle management of electrotechnical complexes in oil production, Russian Electrical Engineering, 2012, V. 83, no. 11, pp. 621–627, DOI: 10.3103/S1068371212110090 15. Petrochenkov A.B., Management of effective maintenance of the electrotechnical complexes of mineral resource industry's enterprises based on energy-information model, IEEE Conference Publications: Proceedings of XVIII International Conference on Soft Computing and Measurements SCM`2015, 2015, pp. 122–124, DOI: 10.1109/SCM.2015.7190430. 16. BochkarevS.V., OvsyannikoM.V., Petrochenkov A.B., Bukhanov S.A., Structural synthesis of complex electrotechnical equipment on the basis of the constraint satisfaction method, Russian Electrical Engineering, 2015, V. 86, no. 6, pp. 362–366, DOI: 10.3103/S1068371215060024. 17. Sudov E.V., Levin A.I., Kontseptsiya razvitiya CALS-tekhnologiy v promyshlennosti Rossii (The concept of development of CALS-technologies in the industry of Russia), Moscow: Publ. of NITs CALS-tekhnologiy “Prikladnaya logistika”, 2002, 28 p., URL: http://old.cals.ru/policy/material/concept_ipi.pdf

This paper presents a drilling/formation stimulation technology Tamyr, enabling to drill multiple microholes that diverge fr om a main horizontal open hole like roots of a tree. The initial horizontal well might be a newly drilled completion or a well under production. The diameter of the micro drainholes is 68 mm, the length is up to 100 m. For oriented sidetracking, a whipstock for open holes is used. To increase its wear resistance, the working surface of the whipstock is nitrogenized to achieve the Vickers hardness number HV 600-650. The coiled tubing-conveyed BHA includes a bottomhole motor with a mill-tooth bit. Following each sidetracking, hydrochloric acidizing of the bottomhole zone is performed: CT-conveyed jet nozzle is run to bottom, then pulled to the point of exit from the main horizontal wellbore with simultaneous injection of hydrochloric acid. Tamyr technology is particularly suited for layered reservoirs with gas-/oil-water contact, wh ere fracture stimulation treatments to enhance production cannot be performed, and for reservoirs with poor porosity and permeability, that is, reservoirs that have been earlier considered marginal. Multiple drainholes maximize reservoir contact and increase wellbore drainage area producing from the isolated reservoir compartments and pockets of bypassed oil not penetrating into the adjacent gas- or water-saturated intervals. Micro drainholes are able to enhance production better than a single-bore horizontal well, being more economical and beneficial at that. Benefits and advantages include less total rig time, fewer materials required for drilling and completion, decreased volumes of drilling fluid and drilling cuttings resulting in reduced disposal costs and less risk of drilling mud invasion. Overall environmental impact is considerably reduced. The technology improves drainage control with much less number of wells and decreased scope of drilling. References 1. URL: https://www.norwegianamerican.com/fishbones-sucks-the-marrow-from-wells/ 2. Patent RU 2684557 C1, Well horizontal shaft drainage zone expansion method by the distant sections acid treatment with the side channels development, Inventors: Ismagilov F.Z., Tabashnikov R.A., Akhmetshin R.M., Ziyatdinov R.Z. 3. Patent RU 2696696 C1, Deflecting device for drilling of branches from horizontal borehole, Inventor: Ziyatdinov R.Z. 4. Patent RU 2709262 C1, Method of drilling and development of offshoot from horizontal well, Inventors: Makhmutov I.Kh., Ziyatdinov R.Z.

The problem of timely detection of ice deposition on overhead power transmission lines is of current concern. To handle this problem an automated transition line icing monitoring system has been developed to enable remote, real-time detection of ice deposition on power transmission lines at early stages and allow for ice buildup control. Control device is attached to power line at a given distance from suspension point, which allows determination of cable tension force for various overhead spans with minimum adjustments in determination algorithms. Power supply of control devices is provided through magnetic component of electromagnetic field. Acquired data are collected at data collection center, then transmitted to cloud-based server and further to computer for processing in a specialized software. If the readings exceed the acceptable values, the operator will receive a priority-response alarm specifying the lines exhibiting maximum tension due to ice deposition. The icing monitoring system has been designed within the scope of research and development project aimed at the development of a comprehensive icing control system for 110-, 35-, and 6(10)-kV high-voltage lines. Currently underway is pilot testing of the system in Oil and gas Production Department Leninogorskneft on F115-05 6-kV overhead line of PS-115 substation and 35-kV overhead line No.115-301. The results suggest acceptable performance of the system. The system of monitoring and quantitative control of ice deposition on power transmission lines based on wireless control devices has additional functional capabilities such as real-time detection of breakpoint location and short-circuit failure of high-voltage lines within each overhead span through measurements of electric current intensity in the line hosting this device. References 1. Ivanov D.A., Savel'ev O.G., Sadykov M.F., Datchik sistemy monitoringa gololedno-vetrovoy nagruzki (Sensor of monitoring system of ice-wind load), Collected papers “Intellektual'nye energosistemy” (Intelligent power systems), Proceedings of IV International Youth Forum, Tomsk, 10–14 October 2016, Tomsk: Publ. of TPU, 2016, Part 1, pp. 138–140. 2. Yaroslavskiy D.A., Sadykov M.F., Konov A.B. et al., Methodology of monitoring ice on wires with considering misalignment of power line armature (In Russ.), Izvestiya vysshikh uchebnykh zavedeniy. Problemy energetiki, 2017, V. 19, no. 5–6, pp. 89–97. 3. Ivanov D.A., Savel'ev O.G., Misbakhov R.Sh., Sistema monitoringa i kolichestvennogo kontrolya gololedoobrazovaniya na provodakh vozdushnykh liniy elektroperedachi (The system of monitoring and quantitative control of icing on the wires of overhead power lines), Collected papers “Energetika, elektromekhanika i energoeffektivnye tekhnologii glazami molodezhi” (Energy, electromechanics and energy-efficient technologies through the eyes of youth), Proceedings of IV Russian youth scientific school-conference, Tomsk, 1–3 November 2016, Tomsk: Publ. of TPU, Part 2, pp. 334–336. 4. Certificate of registration of a computer program no. 2017661562 RF “Programma otobrazheniya dannykh o sostoyanii linii elektroperedach dlya sistemy monitoringa gololedoobrazovaniya” (Power line status data display program for icing monitoring system), Authors: Ivanov D.A., Sadykov M.F., Goryachev M.P., Yaroslavskiy D.A., Chugunov Yu.S., Savel'ev O.G.

At the final stage of oil field development, energy efficiency of oil production processes applying pressure maintenance methods, among which water flooding is the most common one (>90%), takes on great importance. Present-day water flooding is a complex system of various technologies, methods and facilities. Improvement of water-injection system energy efficiency increases oil field productive life. In this regard, reduction of energy consumption is a sophisticated problem to be solved, including search for integrated solutions concerning process design, techniques, procedures, and facilities, especially pumping equipment. More than half of unproductive energy consumption in a water-injection system is attributed to low efficiency of non-positive displacement pumps and forced pressure restriction in order to achieve the required water injection conditions. However, technological development of positive displacement pumps has come ever closer to limitations due to physical features of centrifugal pump units. Nevertheless, centrifugal pumps are still the most commonly used pumping units in water injection systems. Meanwhile, search for new technical solutions and innovative facilities are underway. Plunger-type positive displacement pumps find ever-growing use today. The paper reviews issues of using both non-positive and positive displacement pumps for water injection at NGDU Leninogorskneft’s assets. The authors present energy efficiency indicators for the nearest decade, discuss basic limitations of using non-positive displacement pumps at a present-day stage of field development, compare specific energy consumption for various-size non-positive displacement pumps and plunger-type pumps as a function of pressure. The paper presents the results of studying applicability of a variable frequency drive with high-pressure non-positive displacement pumps. Based on the research results, application of variable frequency drives is limited in terms of both energy efficiency and possibility of injection control, since maximum achievable pump head is restricted along with pump rate reduction, which is often unallowable according to water flooding conditions. The paper also discusses the results of plunger pump implementation at a cluster pumping station as compared with a low-capacity non-positive displacement pump. Process design solutions are presented to improve operational integrity of positive displacement pumps. References 1. Oganesyan S.A., The energy strategy of Russia until 2020, its implementation and prospects for the development of the fuel and energy complex (In Russ.), Energonadzor i energobezopasnost', 2006, no. 2, pp. 30–38. 2. Konnov V.A., Razrabotka energoeffektivnykh metodov i tekhnologicheskikh skhem podderzhaniya plastovogo davleniya pri razrabotke neftyanykh mestorozhdeniy (Development of energy-efficient methods and technological schemes for maintaining reservoir pressure in the development of oil fields): thesis of candidate of technical science, Bugul'ma, 2012. 3. Fattakhov R.B., Konnov V.A., Energy-efficient operation of the pumping equipment of the reservoir pressure maintenance system – a way to reduce the cost of oil (In Russ.), Nefteservis, 2012, no. 4, pp. 33–35. 4. Fattakhov R.B., Konnov V.A., Abramov M.A., Gilyazov R.A., Difficult issues of a “simple” VFD (In Russ.), Izhenernaya praktika, 2013, no. 6, pp. 54–56. 5. Konnov V.A., Fattakhov R.B., Abramov M.A., Application of positive displacement plunger-type pumps in reservoir pressure maintenance systems (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2019, no. 1, pp. 62–65. 6. Fattakhov R.B., Konnov V.A., Ibragimov N.G. et al., Application of positive-displacement pumps for energy savings in reservoir-pressure maintenance systems (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2013, no. 7, pp. 54–57. 7. Konnov V.A., Fattakhov R.B., Analysis of results of experimental operation of positive displacement pumps used for water injection into a formation (In Russ.), Oborudovanie i tekhnologii dlya neftegazovogo kompleksa, 2014, no. 5, pp. 12–15.

Tubingless well operation with electrical submersible pump (ESP) is conducted using a specialized unit to enable lifting of the produced fluid through production string; thus, providing simple, fast and cost-effective well completion, as well as opportunity for rigless well interventions. Research engineers of TatNIPIneft Institute (Tatneft PJSC) have designed a novel tubingless well operation technique that facilitates reduction of production costs due to application of new equipment. The technology for tubingless well operation using ESP was originally used in Well No. 38031 by Oil and Gas Production Department Leninogorskneft. A logging hoist and an automatic winder are installed at the wellhead for tripping of electric submersible pump and for winding of ESP power cable, respectively. A hoisting crane is used to install nipple and ESP. The pumping assembly is run in hole on wireline and set on packer. Advantages of this well operation technology include reduction of well intervention expenditures on pump replacement, mitigation of the costs associated with tubing replacement and repair, and lower risk of cable damage while tripping. These advantages result in OPEX reduction. Increase in oil production rates is achieved due to reduction of water cut. Tubingless operations also yield substantial economic benefit. References 1. Makhmudov S.A., Abuzerli M.S., Montazh, obsluzhivanie i remont skvazhinnykh elektronasosov (Installation, maintenance and repair of borehole electric pumps), Moscow: Nedra Publ., 1995, 223 p. 2. RU 2614426 C1, Pump unit for products lift along the casing string, Inventors: Garifov K.M., Ismagilov F.Z., Artyukhov A.V., Babichev I.N., Lyubetskiy S.V., Kadyrov A.Kh., Glukhoded A.V. 3. Spravochnaya kniga po dobyche nefti (Oil production reference book): edited by Gimatudinov Sh.K., Moscow: Nedra Publ., 1974, 703 р. 4. Shchurov V.I., Tekhnika i tekhnologiya dobychi nefti (Technique and technology of oil production), Moscow: Nedra Publ., 1983, 510 р. 5. Ustanovki pogruzhnykh tsentrobezhnykh nasosov UETsNM i UETsNMK. Rukovodstvo po ekspluatatsii UETsNMRE (Installations of submersible centrifugal pumps UETsNM and UETsNMK. UETsNMRE operation manual), Moscow: Publ. of OKB BN, 1987.

Desorption columns for hydrogen sulfide removal from crude oil by stripping with the hydrocarbon gas were tested in the two Tatneft PJSC high-sulfur oil treatment plants, the Kuakbash and the Kama-Ismagilovo. This paper presents findings from the tests, challenges of the new technological approaches and the solutions. To address the problem of forming of a large amount of condensate and gas in condensate tanks (drips), recirculation and orificing technologies were used. The objective of this work was to raise the quality of stock-tank oil as regards the residual H2S content to meet the requirements of standard GOST R 51858-2002 in the most cost-efficient way. Chemical H2S scrubbing techniques that have been used in the Oil and Gas Production Department Leninogorskneft oil production facilities are rather costly and still do not allow to meet the state standards (GOST) requirements. It has been found that stripping high-sulfur oil with the Devonian hydrocarbon gas in the desorption column was the most effective way to remove H2S from crude oil in the Kuakbash and Kama-Ismagilovo oil treatment plants. However, increase of pressure in the column worsened the quality of crude oil treatment, caused dilution of lubricating oil in the compressor, and led to forming of a large amount of condensate from the stripping gas in drips. To solve these problems, the second stage of separation was introduced in the Kuakbash oil treatment plant, an air cooler was included in the crude oil treatment system to decrease gas temperature downstream of the column and slow down condensing of heavy hydrocarbons upstream of the compressor station; gas recirculation and gas orificing technologies were realized in the Kama-Ismagilovo and the Kuakbash oil treatment plants, respectively, to minimize (exclude) condensate forming in drips of pressure pipelines. These technological solutions made it possible to improve the quality of the stock-tank oil to comply with the GOST requirements. References 1. Ibragimov N.G., Sakhabutdinov R.Z., Shatalov A.N. et al., Hydrogen sulfide removal from oil at tatneft assets (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2013, no. 7, pp. 58–61. 2. Sakhabutdinov R.Z., Shatalov A.N., Garifullin R.M. et al., Technologies of an oil cleaning from hydrogen sulphide (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2008, no. 7, pp. 82–85. 3. Sakhabutdinov R.Z., Shatalov A.N., Garifullin R.M. et al., Analyzing efficiency of chemical neutralization of hydrogen sulphide in oil (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2009, no. 7, pp. 66–69. 4. Ibragimov N.G., Shipilov D.D., Mingazova A.Z. et al., Application of hydrogen sulfide scavengers for oil treating at crude oil treatment facilities of Tatneft OAO (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2014, no. 7, pp. 52–54. 5. Anufriev A.A., Shatalov A.N., Shipilov D.D., Garifullin R.M., Technology of processing of h 2s-containing oil and petroleum gas at kuakbashsky central production facility (In Russ.), Oborudovanie i tekhnologii dlya neftegazovogo kompleksa, 2014, no. 6, pp. 40–43.

The article is devoted to the current topic-solving the problems of oil and gas service development in Russia. Among the measures proposed to the government of the Russian Federation to address them were the formation of consortia, clusters and polygons to create new technologies for the production of hydrocarbons. However, the proposed solutions have not yet been fully implemented. This article attempts to find a solution based on the creation of new organizational forms by oil and gas companies, such as business ecosystems. The authors considered the basic concepts of cluster theory of development and the concept of business ecosystems. It is noted that the features of the domestic oilfield service at the present stage are the development of high-tech areas in exploration, drilling and oil production. This reflects a trend that has developed in world practice. It is shown that the development of oilfield service enterprises is influenced by internal and external factors, among which the most important are highlighted: reduction of prices for hydrocarbon raw materials, improvement of equipment, technologies and staff development. The analysis showed that the formation of business ecosystems in the oil and gas sector should go through a number of stages, including the creation of technological partnerships and innovation and service clusters. The article reflects the experience of their creation in such leading countries as the United States, Norway and the United Kingdom. It is determined that domestic oil and gas and oilfield service companies are following this path. The need to create ecosystems is reflected in the development strategies developed by companies for the future. The authors pointed out that the deteriorating quality of mineral resources, increase the number of fields with hard to recover hydrocarbon reserves located in offshore zone of seas increasing demands on oilfield service companies. They must use new technologies and high-tech equipment for hydrocarbon production, and meet the demand for comprehensive and integrated services. The article concludes that the effective solution of oilfield service problems is possible within the framework of new organizational forms of interaction between oil and gas and oilfield service companies. In the short term, the process of creating technological partnerships and innovation and service clusters should accelerate in the oil and gas sector, and in the medium term, companies ' business ecosystems may be actively developing. References 1. Sevost'yanov N.A., Laptev V.V., On the state policy of Russia in the sphere of oil and gas service (In Russ.), Geologiya nefti i gaza, 2007, no. 2, pp. 25–33. 2. Tyulenev I.V., Razvitie neftegazovogo servisa v Rossii v kontekste mirovogo opyta (The development of oil and gas services in Russia in the context of international experience): thesis of candidate of economic science, 2005. 3. Beloshitskiy A.V., World overview market of oilfield services (In Russ.), Upravlenie ekonomicheskimi sistemami. Elektronnyy nauchnyy zhurnal, 2018, no. 7, URL: http://uecs.ru/index.php?option=com_flexicontent&view=items&id=4999 4. Smorodinskaya N.V., Network innovation ecosystems and their role in the dynamization of economic growth (In Russ.), Innovatsii, 2014, no. 7(189), pp. 28–33. 5. Mitrova T., Grushevenko E., Tekhnologicheskie partnerstva v neftegazovom sektore: primenim li mirovoy opyt kooperatsii v Rossii (Technological partnerships in the oil and gas sector: is the global experience of cooperation in Russia applicable), Moscow: Publ. of Energy Center of the Moscow School of Management Skolkovo, 2018, 39 р. 6. Porter M.E., On competition, Boston: Harvard Business School Press, 1998. 7. Naumova O.N., Peculiarities of territorial clusters formation in modern economics (In Russ.), Vektor nauki TGU, 2014, no. 3 (29), pp. 203–206. 8. Androsik Yu.N., Business ecosystems as a form of cluster development (In Russ.), Proceedings of BSTU, 2016, no. 7, pp. 38–43, URL: https://elib.belstu.by/bitstream/123456789/20306/1/7Androsik.pdf. 9. Adner R., Match your innovation strategy to your innovation ecosystem, HarvardBusinessReview, 2006, V. 84, no. 4, pp. 98–107. 10. Adner R., Ecosystem as structure: An actionable construct for strategy, Journal of Management, 2017, V. 43, no. 1, pp. 39–58. 11. Adner R., Kapoor R., Value creation in innovation ecosystems: How the structure of technological interdependence affects firm performance in new technology generations, Strategic Management Journal, 2010, V. 31, no. 3, pp. 306–333. 12. Gawer A., Cusumano M.A., How companies become platform leaders, MIT Sloan Management Review, 2008, V. 49, no. 2, pp. 28–35. 13. Gomes L., Facin A., Salerno M., Ikenami R., Unpacking the innovation ecosystem construct: evolution, gaps and trends, Technological Forecasting and Social Change, 2018, V. 136, pp. 30–48, DOI: 136. 10.1016/j.techfore.2016.11.009. 14. Sinel'nikov A.A., Formirovanie strategicheskikh planov ustoychivogo razvitiya neftegazovoy kompanii: problemy i metody (Formation of strategic plans for the sustainable development of the oil and gas company: problems and methods), Moscow: Publ. of Gubkin University, 2018, 295 p.

The Kashirskian sequences of Moscovian stage of Middle Carboniferous series are oil-and-gas-bearing deposits in the Republic of Bashkortostan, but they remain underinvestigated. The most of oil deposits are concentrated in the northwest part of republic. Oil flow rates of single well sometimes rich 50 CMPD and more, but often there are water influx of wells in close proximity. At present time there are not identificated any patterns of reservoirs and seal-rocks development area. There is a problem with oil-saturated reservoir-rocks allocation as a result of geophysical data interpretation. The Kashirskian sequence contains a large amount of dolomite, but the questions of its genesis, patterns of its development area and relationships with reservoir properties are controversial. Kashirskian sequence has a cyclic structure which is typical for epeiric seas. The survey resulted in the identification of elementary “shallowing upward” sequences with 3-8 meters thickness. They can be merge into sequences of higher range, visible on the log curves. The composition of idealized Kashirskian sequence is given below. Low-porosity bioturbated wackstones of subtidal zone is at the bottom. Above are intertidal bioclastic grainstones with high porosity and permeability. The upper member of the sequence is microcrystalline dolomites with high porosity (10–25% and more) and low permeability. The research is aimed to study various levels of cyclicity, lithological features of each part of cyclothem and its relationships with reservoir properties. Layers of paleosoils on the top of sequences mark breaks in sedimentation. Analysis shows different types of reservoirs distribution in the section. Probably, water influxes in some wells related to lenticular bodies of microporous dolomites with high residual water saturation. It’s necessary to conduct thin-layer correlation, based on wells with core and cuttings and enhanced well-logging methods to define development areas of grainstones and microporous dolomites. It will help to create reliably geological framework and improve drill efficiency. References 1. Burikova T.V., Savel'eva E.N., Husainova A.M. et al., Lithological and petrophysical characterization of Middle Carboniferous carbonates (a case study from north-western oil fields of Bashkortostan) (In Russ.), Neftjanoe hozjajstvo = Oil Industry, 2017, no. 10, pp. 18–21. 2. Van Lith Y., Warthmann R., Vasconcelos G., Mckenzie J.A., Microbial fossilization in carbonate sediments: a result of bacterial surface involvement in dolomite precipitation, Sedimentology, 2003, V. 50, pp. 237–245. 3. Kirkham A., Patterned dolomites: microbial origins and clues to vanished evaporates in the Arab Formation, Upper Jurassic, Arabian Gulf, London: Geological Society, 2004, V. 235, pp. 301–308. 4. Samylina O.S., Zaytseva L.V., Sinetova M.A., Participation of algal–bacterial community in the formation of modern stromatolites in Cock Soda Lake, Altai Region (In Russ.), Paleontologicheskiy zhurnal = Paleontological Journal, 2016, no. 6, pp. 92–101.

The article presents the results of the research conducted by Rosneft Oil Company on the study of the problems of combining heterogeneous heterogeneity of oil and gas deposits, which largely determines the reliability of geological and hydrodynamic three-dimensional digital models of hydrocarbon deposits. The article is devoted to the problem of combining the results of various studies in constructing a geological model of an oil and gas deposit. Five methods of accounting for data obtained in a detailed study of smaller objects are considered. The first method involves averaging and/or coarsening of the data obtained as a result of studies of smaller objects. The second method involves the integration of multidimensional studies based on the identification and generalization of functional heterogeneity (significant functional disturbances or deviations from the revealed dependencies, trends, distributions, etc.). Its application allows in some cases to identify structural features of target objects. The third method is based on the need to take into account the general laws of development of the processes of formation of productive deposits during the integration of multi-scale studies. In this case, the general laws of development of the processes of formation of productive deposits, determined on the basis of detailed studies of smaller geological bodies, are taken into account. The fourth method is based on the use of stochastic and statistical methods. It allows you to quite successfully partially fill in the missing information on detailed studies of smaller bodies. The fifth method involves the implementation of auxiliary modeling. When studying a larger geological body, not the data of detailed studies of smaller objects are used, but the corresponding models, reduced to the corresponding scale. References 1. Strakhov P.N., Koloskov V.N., Bogdanov O.A., Sapozhnikov A.B., Issledovanie neodnorodnostey neftegazonosnykh otlozheniy (Investigation of heterogeneity of oil and gas deposits), Moscow: Publ. of Gubkin University, 2018, 189 p. 2. Dulkarnaev M.R., Skachek K.G., Belyakov E.O., Takkand G.V., New method of modelling filtration-characteristics granular reservoir rocks (on example Povhovskoe field) (In Russ.), Geoinformatika, 2011, no. 3, pp. 47–50. 3. Slavkin V.S., Strakhov P.N., Frenkel' S.M., Possibility of determining the permeability of pore-type reservoirs according to well log data (In Russ.), Geologiya, geofizika i razrabotka neftyanykh mestorozhdeniy, 1997, no. 2, pp. 17–21. 4. Levorsen A.I., Geology of petroleum, The AAPG Foundation, 2001, 724 p. 5. Bogdanov O.A., Strakhov P.N., Assessment of the filtration properties of terrigenous sediments of the Cenomanian stage of the northern part of Western Siberia during the construction of geological models of hydrocarbon deposits (In Russ.), Nauka i tekhnika v gazovoy promyshlennosti, 2017, no. 1, pp. 3–8. 6. Khanin A.A., Porody-kollektory nefti i gaza neftegazonosnykh provintsiy SSSR (Reservoir rocks of oil and gas of the USSR petroliferous provinces), Moscow: Nedra Publ., 1969, 368 p.

The decisive influence on the technology of drilling wells in Eastern Siberia is exerted by a complex of components of the geological section, the absorption of flushing fluid, AAP and temperature. Experience in well construction shows that in the fields, drilling was carried out on two types of water and oil-based fluids. Due to various circumstances, each of the types of solutions used in drilling had negative aspects during the construction of wells. The use of such solutions is not effective enough to solve the problem of opening intervals of salt deposits and high-quality primary opening of reservoirs. In order to assess the effectiveness of well construction, we applied the methodology for determining the potential production rate of wells based on the Dupuit formula for an imperfect vertical well. Analysis of the potential flow rates of wells built on the terrigenous reservoir of the Vostochno-Alinskoye field using traditional technologies (saturated saline biopolymer solution) showed that more than half of the wells did not reach potential productivity. The existing technology of well completion under conditions of constant repression on the reservoir, including the secondary opening of the productive horizon, negatively affects the reservoir properties of the object. Under the conditions of Vostochno-Alinskoye field the effective opening of the reservoir should be solved by applying technologies that prevent the penetration of working fluids and their filtrates into the reservoir. The essence of such technologies should be based on the creation of conditions that do not allow the excess of bottomhole pressure over the reservoir pressure of the exposed horizon. References 1. Parfir'ev V.A., Paleev S.A., Vaganov Yu.V., The analysis of oil wells construction in abnormal conditions in Eastern Siberia oil-fields (In Russ.), Izvestiya vuzov. Neft' i gaz, 2018, no. 1, pp. 48–53. 2. Apenyshev D.S., Karlov A.M., Parfir'ev V.A. et al., Results of morphotectonic analysis of Talakanskoye field (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2008, no. 2, pp. 12–19. 3. Angelopulo O.K., Podgornov V.M., Avakov V.Z., Burovye rastvory dlya oslozhnennykh usloviy (Drilling fluids for complicated conditions), Moscow: Nedra Publ., 1988, 13 p. 4. Eder L.V., Filimonova I.V., Moiseev S.A., The oil and gas industry in Eastern Siberia and the Far East: trends, challenges, current status (In Russ.), Burenie i neft', 2015, no. 12, pp. 3–14. 5. Gladkov E.A., Shiribon A.A, Karpova E.G., Ways solutions of the problems encountered during drilling in Eastern Siberia (In Russ.), Burenie i neft', 2015, no. 4, pp. 42–45. 6. Parfir'ev V.A., Vaganov Yu.V., Zakirov N.N., Paleev S.A., Application of hydrocarbon-base mud during the initial opening and drilling of the productive horizon of field in the Eastern Siberia (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2019, no. 12, pp. 74–79. 7. Parfir'ev V.A., Paleev S.A., Zakirov N.N, Vaganov Yu.V., Multisalt biopolymer mud for well construction at fields with terrigenous reservoir in Eastern Siberia (In Russ.), Izvestiya vuzov. Neft' i gaz, 2018, no. 1, pp. 48–53. 8. Basarygin Yu.M., Budnikov V.F., Bulatov A.I., Proselkov Yu.M., Tekhnologicheskie osnovy osvoeniya i glusheniya neftyanykh i gazovykh skvazhin (Technological fundamentals of development and killing of oil and gas wells), Moscow: Nedra-Biznestsentr Publ., 2001, 543 p. 9. Basarygin Yu.M., Bulatov A.I., Proselkov Yu.M., Tekhnologiya kapital'nogo i podzemnogo remonta neftyanykh i gazovykh skvazhin (The technology of oil and gas well servicing and workover), Krasnodar: Sovetskaya Kuban' Publ., 2002, 584 p. 10. Ryazantsev E.F., Karnaukhov M.L., Belova A.T., Ispytanie skvazhin v protsesse bureniya (Well testing while drilling), Moscow: Nedra Publ., 1982, 310 p. 11. Bubnov A.V., Kozyar V.F., Nikolaenko Yu.V. et al., Rekomendatsii po metodike geofizicheskikh issledovaniy skvazhin i geologicheskoy interpretatsii materialov dlya neftegazonosnykh rayonov Vostochnoy Sibiri (Recommendations on the methodology of geophysical research of wells and geological interpretation of materials for oil and gas regions of Eastern Siberia), Kalinin: Publ. of VNIGIK, 1984, 267 p. 12. Povalikhin A.S., Kalinin A.G., Bastrikov S.N., Solodkiy K.M., Burenie naklonnykh, gorizontal’nykh i mnogozaboynykh skvazhin (Directional, horizontal and multihole drilling), Moscow: Publ. of TsentLitNefteGaz, 2011, 645 p. 13. Tagirov K.M., Nifantov V.I., Burenie skvazhin i vskrytie neftegazovykh plastov na depresii (Drilling and opening of oil and gas reservoirs at depressions), Moscow: Nedra-Biznestsentr, 2003, 160 p. 14. Tekhnologiya bureniya neftyanykh i gazovykh skvazhin (Oil and gas well drilling technology): edited by Ovchinnikov V.P., Part 3, Tyumen: Publ. of TIU, 2017, 341 p. 15. Ohmer J.F., Rosharon T.P., Milan M.K. et al., New aspects of multilateral well construction, Oilfield Review, 2002, Autumn, pp. 52–69. 16. Bulatov A.I. Demikhov V.I. Makarenko P.P., Kontrol' protsessov bureniya neftyanykh i gazovykh skvazhin (Monitoring of oil and gas well drilling processes), Moscow: Nedra Publ., 1998, 345 p.

Currently, a lot of major oil fields are in the latter stages of development, when the water-cut exceeds 90%. At the same time, the development of reserves of the edge zones and residual reserves by sidetraking with the preservation of the main hole, and dual completion require new approaches to planning the trajectory in the construction of wells. In this regard, quite a topical subject is the design of borehole trajectory with the possibility of the subsequent sidetracking with minimal values of the intensity of curvature of the spatial angle. Typically, the trajectories of the main and side boreholes are designed using various certified computer programs. However, the toolkit applicable in the programs is identical and depends on the coordinates of the targets; in advanced software products there are various tools to optimize the well profile, but only in case of one drilling target. The article presents the method of prompt calculation of the main parameters of a borehole profile at any location of the branch point of the sidetrack taking into account the requirements for the intensity of curvature and anti-aircraft angle. The methods of changing the profile of the sloping well with the aim of later drilling of the sidetrack reduce the risks of complications by significantly optimizing all parameters. The parameters of main borehole profile received by the proposed methods of determining the coordinates of the branch point are significantly different from the results of traditional method. In the result of parameters changing (anti-aircraft angle, curvature intensity, length of open trunk) the profile of the main hole becomes more complicated, because below the depth of the intended window clipping, it is necessary to change the azimuth. The use of the method of calculating the coordinates of the point of the sidetrack window clipping is also possible in the planning of exploratory and operational wells for additional fishing and geophysical research in the pilot holes. References 1. Abdullin A.V., Abdullin I.K., Barannikov Ya.I., Maksimov A.Yu., Use of layouts of dual production operation and dual injection operation, during sidetracks drilling without liquidation of the basic one (paternal) (In Russ.), Neftepromyslovoe delo, 2020, no. 3, pp. 41–44. 2. Bakirov D.L., Mazur G.V., Babushkin E.V. et al., Improving technology of horizontal sidetracking in complicated geological-technical conditions (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2019, no. 8, pp. 40–43. 3. Budyanskiy V.S., Vlasov V.A., Krekin M.V. et al., Development of the technology of directional and horizontal drilling based on direct components arrangement (In Russ.), Stroitel'stvo neftyanykh i gazovykh skvazhin na sushe i na more, 2019, no. 6, pp. 5–8. 4. Shcherbakov A.V., Determination of place of additional wellbore drilling in a multilateral well (In Russ.), Stroitel'stvo neftyanykh i gazovykh skvazhin na sushe i na more, 2015, no. 10, pp. 18–23.

This article is devoted to the optimization of the development of one of the oilfields of Udmurtneft JSC by changing the injection agent in the reservoir pressure maintenance system (RPMS) from fresh water to reservoir water. The article describes in detail the disadvantages of the current RPMS and the advantages of changing the displacement agent. The compatibility of associated produced water and formation water of the Serpukhovian as a source of injection is evaluated. Petrophysical functions of oil displacement efficiency depending on the injection agent are shown. According to the results of numerical modeling the increase in additional oil production by 17.9 thousand tons is predicted. Due to this, as well as due to savings on the purchase and transportation of fresh water, the economic effect of the introduction of the proposed technology is estimated at 56.7 million rubles. The algorithm of step-by-step transition to reservoir water injection presented in the article includes all stages of the process, starting with geological exploration and ending with the taking down of a low-pressure water pipeline and the injection of reservoir water into the formation. The described method of assessment of displacement agent change efficiency can be applied to other oilfields under the waterflooding development. The generalized algorithm describes an approach to changing the injection agent in such fields. References 1. Prokhorov A.Yu., Kurchikov A.R, Mitrofanov A.D. et al., Impact of water, pumped into layer, on oil recovery out of deposits of Jurassic period (Urnensky and Ust-Tegussky oil fields) (In Russ.), Neftepromyslovoe delo, 2010, no. 9, pp. 13–18. 2. Mashorin V.A., Fominykh O.V., Cherevko M.A., Substantiation of fresh water injection for formation pressure maintenance at Verkhne-Shapshinsky field (In Russ.), Territoriya NEFTEGAZ, 2014, no. 5, pp. 82–86. 3. Dake L.P., The practice of reservoir engineering, Elsevier Science, 2001, 570 p. 4. Nazarov V.D., Nazarov M.V., Treatment of fresh and process waters for the reservoir pressure maintenance system in the oil fields (In Russ.), Izvestiya vuzov. Neft' i gaz, 2013, no. 2, pp. 40–47. 5. Mashorin V.A., Substantiation of fresh water usage for formation pressure maintaining of oil fields (In Russ.), Neftepromyslovoe delo, 2014, no. 10, pp. 27–31.

The paper presents the review of investigations carried out in UfNII-BashNIPIneft in the 1960-1980s on the problem of oil displacement by means of CO2 (CO2 flooding). CO2 flooding belongs to miscible oil displacement methods capable to extract all the oil from the porous-permeable medium. Historically two technologies have been proposed and tested in field conditions: 1) in the form of carbonized water as a displacing agent and 2) in the form of an oil trim (composite oil trims) of liquid carbon dioxide of a certain concentration and size, pushed through the reservoir by water. The first technology is rated as ineffective. Today, the second technology is the best option. The mechanism of action of this technology has been studied. At VNII, BashNIPIneft, and SibNII NP there have been developed methods for calculating technological indicators of field development with CO2 flooding. BashNIPIneft, which had became responsible in the Ministry of Oil and Gas Industry for the CO2 problem, periodically compiled feasibility studies for industrial oil production using carbonized water (1975), later – liquid carbon dioxide (1976-1977) in the fields of the USSR. Technological schemes of CO2 flooding for enhanced oil recovery (EOR) on Abdrakhmanovskaya area of Romashkinskoye field, Chashinskoye, Olkhovskoye, Radaevskoye, Kozlovskoye fields and experimental plots of Sergeevskoye oilfield have been made. Due to the lack of knowledge on CO2 flooding in the local oil industry and, consequently, the lack of technical means for implementing the process, BashNIPIneft specialists have issued proposals for creation of domestic equipment at priority fields. Samples of domestic pumping equipment, pipelines and fittings for operation in CO2 environment have been tested at a test range. Laboratory studies have confirmed that regeneration of CO2 from its mixture with associated petroleum gas is the main technology that meets the requirements of the national economy development. Recommendations to renovate the investigations and industry tests on CO2-fluding in Russian Federation have been given. References 1. Muskat M., Oil Recovery – 100 percent, Industrial&Engineering Chemistry, 1953, V. 45, no. 7, pp. 1401–1405. 2. Lyutin A.V., Serebrennikov S.A., Laboratornye issledovaniya po primeneniyu uglekisloty dlya polnogo udaleniya nefti iz prizaboynoy zony i dlya uvelicheniya nefteotdachi (Laboratory studies on the use of carbon dioxide to completely remove oil from the bottomhole zone and to increase oil recovery), Proceedings of VNII, 1958, V. 15, pp. 23–36. 3. Babalyan G.A., Tumasyan A.B., Panteleev V.G. et al., Primenenie karbonizirovannoy vody dlya uvelicheniya nefteotdachi (The use of carbonated water to increase oil recovery), Moscow: Nedra Publ., 1976, 143 p. 4. Lozin E.V., Effektivnost' dorazrabotki neftyanykh mestorozhdeniy (The effectiveness of further development of oil fields), Ufa: Bashknigoizdat Publ., 1987, 152 p. 5. RD 39-3-69-78. Rukovodstvo po proektirovaniyu i primeneniyu metoda zavodneniya s CO2 (Guidelines for the design and application of CO2 flooding method), Ufa: Publ. of Bashnipineft', 1978, 51 p. 6. Yellig W.F., Metcalfe R.S., Determination and prediction of CO2 minimum miscibility pressures, SPE 7477-PA, 1980. 7. Levi B.I., Shakirov Kh.G., Metodika prognozirovaniya protsessa vytesneniya nefti otorochkami dvuokisi ugleroda i vody (Method for predicting the process of oil displacement by rims of carbon dioxide and water), Ufa: Publ. of Bashnipineft', 28 p. 8. Bennacer K., Enhanced oil recovery and CO2, Ufa: Publ. of Schlumberger, 2006, 43 p.

Many oil companies have diversified portfolios of assets that consist of highly depleted conventional oil reserves coupled with unconventional oil in Domanic formation. Oil bearing pay zone at the Bavlinskoye field is represented by low-permeability Domanic formation, which is composed of carbonate rocks with interlayers of poorly permeable and enriched organic matter calcareous-siliceous or siliceous-calcareous rocks in the section. The main methods of oil production stimulation from such reservoirs are hydraulic fracturing and injection of compositions based on hydrochloric acid, both allowing to increase the permeability of the reservoir due to the formation of new highly permeable channels (hydraulic fracturing and dominant wormholes). Experimental studies have shown that the structure of these channels is predetermined by the conditions of the reservoir depletion, including the fluid flow properties, temperature, injection rate, as well as the composition and properties of workover fluids. Under the Federal Research Program “Research and Development in Priority Areas for the Development of the Russian Science and Technology for 2014-2020” and pursuant to agreement 14.607.21.0195 Almetyevsk State Oil Institute conducted work on the scope of “Development of scientific and technological solutions for the development of unconventional reservoirs and hard-to-recover oil reserves (bituminous oils) based on experimental studies”, aimed at increasing production by hydraulic fracturing and acid treatment in the wells drilled in Domanic formation. A comprehensive account of factors that significantly influence the effectiveness of workovers (geological and physical parameters of the reservoirs as well as technogenic impact associated with the peculiarities of the reservoir development scenario) enabled us to identify the optimal compositions taking into account the design of hydraulic fracturing and acid treatment during pilot workovers implemented in the wells at Bavlinskoye field. The use of numerical simulators to optimize the process of acid treatment and hydraulic fracturing resulted in economically viable solution due to the screening of different injection volumes, variation in the speed of injection and applied auxiliary ingredients for the developed composition. References 1. Zakirov I.S., Zakharova E.F., Musabirov M.Kh., Ganiev D.I., Approaches to assessing the effectiveness of chemicals on core material of Domanic deposits (In Russ.), Neftyanaya provintsiya, 2019, no. 3(19), pp. 141–155. 2. Khisamov R.S., Zakirov I.S., Zakharova E.F. et al., Experience of studying and development of Domanic deposits on the example of Bavlinskoye field of the Republic of Tatarstan (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2018, no. 11, pp. 78–83. 3. Zakirov I.S., Zakharova E.F., Orekhov E.V. et al., Features of studying the structure of the void space of Domanik formations on the basis of tomographic (In Russ.), Neftyanaya provintsiya, 2019, no. 2(18), pp. 25–42.

The paper presents the results of the single well chemical tracer tests (SWCTT) conducted in the Kharyaginskoye carbonate reservoir to estimate residual oil saturation before and after of low-salinity water flooding. Previously core-studies were conducted to estimate the effectiveness of low-salinity water flooding. The SWCTT is based on chemical transformations of substances into the bottomhole zone of the well. Reactive chemical tracer is injected into the reservoir through the production well. After that the volume of tracers is pushed into the reservoir with an additional volume of water. The well is then 'shut in' while some of the reactive tracer is allowed to undergo a hydrolysis reaction within the reservoir. Following 'shut in' period, the well is produced to bring back the fluid, with sampling and analysis for the presence of indicators. The reaction product, alcohol tracer and unreacted ester tracer undergoes a chromatographic separation. The magnitude of this separation depends on the oil/water ratio in the reservoir and the ester partition coefficient, thereby allowing to calculate residual oil saturation. The depth of investigation area was roughly 3.5 m from the wellbore. Effectiveness of flooding is estimated, based on the values of the residual oil saturation before and after the treatment. The article also presents the results of laboratory tests on core samples to determine the effectiveness of low-saline water injection, the values of the separation and hydrolysis coefficients required when interpreting the SWCTT results, and describes the practical part on the field of the experiment. As a result of the work, a numerical assessment of the effectiveness of low-saline water injection in the Kharyaginskoye oil field was obtained. References 1. Patent 3623842 USA, Method of determining fluid saturations in reservoirs, Inventor: Deans H.A. 2. Tomich J.F., Dalton R.L., Deans H.A. et al., Single-well tracer method to measure residual oil saturation, SPE-3792-PA, 1973. 3. Deans H.A., Carlisle S., Single-well chemical tracer test handbook, Laramie, Wyoming: Chemical Tracers, Inc., 2007. 4. Al-Abbad M., Balasubramanian S., Sanni M. et al., Single-well chemical tracer test for residual oil measurement: field trial and case study, SPE-182811-MS, 2016. 5. Jerauld G.R., Mohammadi H., Webb K.J., Interpreting single well chemical tracer tests, SPE-129724-MS, 2010. 6. Akhmetgareev V.V., Issledovanie protsessov razrabotki neftyanykh kollektorov nizkomineralizirovannym zavodneniem na osnove modelirovaniya (na primere mestorozhdeniy Respubliki Tatarstan) (The study of the processes of developing oil reservoirs by low-mineralized waterflooding based on modeling (on the example of oilfields in the Republic of Tatarstan)): thesis of candidate of technical science, 2016. 7. De Zwart A.H. et. al., Numerical interpretation of single well chemical tracer tests for ASP injection, SPE-141557-MS, 2011.

The article discusses the unique technology for improved oil recovery using RBS-3 and DGK-2 reagents. The content of chelating compounds in the RBS-3 and DGK-2 reagents makes it possible to clean the bottom-hole formation zone fr om contamination that is not removed by other reagents. The reactivity of the reagents is maintained at temperatures up to 200°C. The technology based on the RBS-3 reagent is intended for cleaning the bottom-hole zone of wells from clay drilling crust, drilling mud residues with barite fillers, deposits of insoluble heavy metal salts, clay particles, iron oxides and hydroxides, insoluble products of the reaction of hydrochloric acid with rock, hydraulic fracturing gels based on guar and polyacrylamide. The DGK-2 reagent is an acidic form of the RBS-3 reagent with increased reactivity for carbonates. The technology based on DGK-2 is intended for processing production and injection wells in carbonate reservoirs as an alternative to hydrochloric acid treatments, in parts wh ere they do not produce an effect or a weak effect during repeated acid treatments, and under certain conditions – and hydraulic fracturing. RBS-3 and DGK-2 reagents have passed the stage of laboratory testing and field tests. Thus, at exploratory well on the one of the fields in the Republic of Kalmykia, when testing the search object in the carbonate deposits of the Lower Triassic formation, characterized by abnormally complex reservoir conditions - a depth of 5300 m, a pressure of 91.5 MPa, a temperature of 177°C, after unsuccessful attempts to cause an influx using traditionally used acid compositions, the use of technology based on the RBS-3 reagent allowed to obtain an industrial inflow of gas and condensate and open a new hydrocarbon field. The DGK-2 treatment of production wells at the carbonate reservoir in the Timan-Pechora region allowed increasing the flow rates of liquid by 2.9-4.0 times and oil by 2.0-2.7 times, which is comparable to the efficiency of hydraulic fracturing. The average increase in oil production was almost 9 tons per day, and the volume of additional oil production for the 7 months since the start of operations – 5600 tons or 1400 tons per well. Technologies for intensifying oil production with the use of reagents RBS-3 and DGK-2 are recommended for wide industrial applications for cleaning the bottom-hole formation zone from various types of production induced pollution in difficult reservoir conditions. References 1. Patent RU 2581859 C1, Composition for treatment of bottomhole formation zone, Inventor: Fakhretdinov R.N. 2. RF patent application no. 2019120610. Sostav dlya obrabotki prizaboynoy zony karbonatnogo kollektora (Composition for processing bottom-hole zone of carbonate reservoir). 3. Khimiya i khimicheskaya tekhnologiya. Khelanty (Chemistry and chemical technology. Chelants), In: Spravochnik khimika 21 veka (21st Century chemist handbook), URL: https://chem21.info/info/427626/ 4. Khelaty (Chelates), In: Bol'shaya rossiyskaya entsiklopediya (Great Russian Encyclopedia), URL: https://bigenc.ru/chemistry/text/4664013

The article is devoted to the mathematical modeling of technological operations with coiled tubing (CT) and software development for the CT operations design, execution and quality control. The purpose of coiled tubing technology and types of technological operations that are performed in the well using coiled tubing are considered. Examples of application of software for modeling operations with coiled tubing – a СТ simulator are considered. The basic physical phenomena that must be taken into account for the correct CT modeling are described. A general description of the mathematical models and submodels that make up the CT simulator is given: forces calculation, CT stability loss types and criteria, the effect of hydraulics on the CT stress state, CT critical stress criteria, multiphase hydraulics, solids transport, fatigue failure. The description of the basic principles used in the development of the domestic CT simulator is given: a unified user interface for input data and displaying calculation results, performing a standard CT simulation in one run, an extensive database of CT, pipes, CT surface and bottom hole assembly, liquids, gases. The capabilities of a special software application for the data acquiring, processing and visualization in the coiled tubing / hydraulic fracturing fleets control station are described: the ability to display any graphs and scales on any number of windows and in any configuration: adaptive selection of graph sizes, scales and indicators, flexible adjustment of parameters for parsing the input data stream, which allows to adapt to any format of the text protocol; unlimited number of input channels; the ability to create calculated data channels. At present, the corporate coiled tubing simulator and the data acquiring, processing and visualization software are being tested by the internal fracturing and coiled tubing service at the fields of Rosneft’s production units. References 1. Ho H.-S., An improved modeling program for computing the torque and drag in directional and deep wells, SPE- 18047-MS, 1988, doi:10.2118/18047-MS. 2. Johancsik C.A., Friesen D.B., Dawson R., Torque and drag in directional wells-prediction and measurement, SPE-18047-MS, 1984, doi:10.2118/11380-PA. 3. Sheppard M.C., Wick C., Burgess T., Designing well paths to reduce drag and torque,SPE-15463-PA, 1987, doi:10.2118/15463-PA. 4. Mitchell R.F., Samuel R., How good is the torque/drag model, SPE-105068-PA, 2009, doi:10.2118/105068-PA. 5. Mirhaj S.A., Kaarstad E., Aadnoy B.S., Torque and drag modeling; soft-string versus stiff-string models, SPE-178197-MS, 2016, doi:10.2118/178197-MS. 6. Newman K.R., Finite element analysis of coiled tubing forces, SPE-89502-MS, 2004, doi:10.2118/89502-MS. 7. Newman K., Bhalla K., McSpadden A., Basic tubing forces model (TFM) calculation, Tech Note CTES, Texas, 2003. 8. Wu J., Juvkam-Wold H. C., Coiled tubing buckling implication in drilling and completing horizontal wells, SPE-26336-PA, 1995, doi:10.2118/26336-PA. 9. Feodos'ev V.I., Soprotivlenie materialov (Strength of materials), Moscow: Publ. of MSTU named after N.E.Bauman, 1999, 592 p. 10. Bhalla K., Walton I.C., The effect of fluid flow on coiled tubing reach, SPE-36464-PA, 1998, doi:10.2118/36464-PA. 11. Kaya A.S., Comprehensive mechanistic modeling of two-phase flow in deviated wells, Oklahoma: The University of Tulsa, 1998, 93 p. 12. Caetano E.F., Upward vertical two-phase flow through an annulus: PhD dissertation, Oklahoma: The University of Tulsa, 1985. 13. Beggs H.D., Brill J.P., A study of two-phase flow in inclined pipes, JPT, 1973, May, pp. 607–617. 14. Zhang H.-Q., Wang Q., Sarica S., Bril J.P., Unified model for gas-liquid pipe flow via slug dynamics. Part 1: Model development, J. Energy Res. Technol., 2003, no. 125. 15. Avakov V.A., Foster J.C., Smith E.J., Coiled tubing life prediction, OTC-7325-MS, 1993, pp. 627–634.

When measuring the mass of oil and oil products during their transportation through the system of main pipelines, a significant contribution to the measurement error is made by flow converters (flow meters) and density, which are part of the measurement systems for the quantity and quality of oil and oil products (SIC). Also, when calculating the mass of oil and petroleum products, the results of viscosity, pressure and temperature measurements are used. Currently, turbine flow meters, mass flow meters, ultrasonic flow meters, chamber flow meters, density converters, and viscosity converters are used to measure the quantity, density, and viscosity of oil and petroleum products in Russia and abroad. The article is devoted to the study of the influence of rheological properties of the working medium on the metrological characteristics of flow meters of various designs. For studies the authors selected turbine flow meter (made in Russia), ultrasonic flowmeter (production of of the Netherlands), a mass flow meter (made in UK). The research was carried out in two stages – on a specialized test bench (with working media diesel fuel, industrial oil ILS-5, spindle oil) and on the SIC (with working medium oil). Such research, which includes testing of flow meters in a wide range of viscosities and costs in real working environments, was conducted in Russia for the first time. The article discusses the first stage of testing. The general principles and laws that affect the flow meter readings, stability and reliability of their operation are considered, and the description of the applied research methods and processing of statistical data obtained during tests is given. The second part of the article describes the process of testing flowmeters, analyzes the test results, describes the comparison of calibration characteristics of flowmeters, analyzes the impact of operating conditions on metrological characteristics, and compares the values of the standard deviation (RMS). References 1. Kazantsev M.N., Timofeev F.V., Zamalaev S.N., Gil'manov M.R., Methods of detection, elemination and formation prevention of asphalt, resin and paraffin deposits in main oil pipelines (In Russ.), Nauka i tehnologii truboprovodnogo transporta nefti i nefteproduktov = Science & Technologies: Oil and Oil Products Pipeline Transportation, 2016, no. 3, pp. 50–56. 2. Korolenok A.M., Lur'e M.V., Timofeev F.V., Extending range of light oil products butched through pipelines pipelines (In Russ.), Nauka i tehnologii truboprovodnogo transporta nefti i nefteproduktov = Science & Technologies: Oil and Oil Products Pipeline Transportation, 2012, no. 4 (8), pp. 40–43. 3. Panfilov S.A., Savanin A.S., Analysis of the influence of the reliability and stability of metrological characteristics of measuring instruments on the intertesting interval (In Russ.), Polzunovskiy vestnik, 2013, no. 2, pp. 277–280. 4. Kolbanev N.I., Timofeev F.V., Sereda S.V., Sovershenstvovanie sistemy ispytaniy nefteproduktov (Improving the petroleum product testing system), Proceedings of XV National Scientific and Practical Conference “Metrologiya 2019” (Metrology 2019), Sofiya, Bolgariya, 2019, pp. 42–44. 5. Galyamov A.K., Shammazov A.M., Tagirov R.Sh. et al., Investigation of the effect of gas on the accuracy of turbine flow meters (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 1983, no. 4, pp. 47–49. 6. Ibragimov N.G., Samoylov V.V., Frolov A.I. et al., Analysis and selection of flow measuring instruments in RPM systems and gas collection networks (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2002, no. 3, pp. 74–78. 7. Obshchaya teoriya statistiki (General theory of statistics): edited by Shmoylova R.A., Moscow: Finansy i Statistika Publ., 2002, 560 p. 8. Aralov O.V., Buyanov I.V., Savanin A.S., Shimel' N.A., Mathematical modeling of a helical flowmeter for oil and oil products (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2018, no. 6, pp. 140–144. 9. Saboohi Z., Sorkhkhah S., Shakeri H., Developing a model for prediction of helical turbine flowmeter performance using CFD, Flow Measurement and Instrumentation, 2015, V. 42, рр. 47–57, DOI: 10.1016/j.flowmeasinst.2014.12.009 10. Lisin Yu.V. Aralov O.V., Savanin A.S., Reduction of the limits of permissible relative error of the indirect method of dynamic measurements of the mass of oil and oil products (In Russ.), Zakonodatel'naya i prikladnaya metrologiya, 2016, no. 2 (141), pp. 17–20.

Vietsovpetro successfully develops offshore hydrocarbon deposits located on Block 09-1 of the South Vietnam Shelf. At present, about 50 offshore facilities operate in Vietsovpetro. In the future, it is planned to build more than 10 wellhead platforms, with applied unmanned technology. Improving the efficiency of the enterprise lies in the field of optimization of offshore facilities and field infrastructure. The key to success is the comprehensive implementation of various measures that can have both an economic and a safety effect. At present, the company is in need of expanding the possibility of safe transfer of personnel from vessels to unmanned wellhead platforms of Vietsovpetro, since today the personnel is being delivered by helicopter, transfer basket or crane equipment. It is known that workers transfer using basket and crane located on the platform requires significant time, involvement of maintenance personnel and is not safe compared to the use of special transfer devices. Besides, waiting on crane by the vessel with dynamic positioning system leads to additional fuel costs. The article describes the possibilities of optimizing the current logistics scheme of passenger turnover at Vietsovpetro fields by implementation of the modern and safe transfer method – Walk-to-Work (W2W) systems, gives an idea of these systems and global application experience. W2W offers personnel a convenient opportunity to move from the side of the vessel to the offshore structure and vice versa without the use of vertical stairs and ladders. The phrase itself draws a parallel between the usual walk and the transition to the platform, emphasizing the ease and safety of this procedure. Unlike helicopter, which requires flight schedule adjustment, vessel-platform crossing system allows using these vessels for transfer “on demand” basis, almost immediately upon request if necessary. In addition, the use of this system can significantly reduce the cost of expensive helicopter maintenance. References 1. DNVGL-ST-0358. Offshore gangways, 2017, URL: https://rules.dnvgl.com/docs/ pdf/DNVGL/ST/2017-09/DNVGL-ST-0358.pdf 2. Nastavlenie po tekhnike bezopasnosti pri peresadke lyudey s odnogo sudna na oshvartovannoe k nemu drugoe v otkrytom more i na otkrytykh reydakh (Safety manual for the transfer of people from one ship to another moored to it in the open sea and on open roads), Klaypeda: Publ. of Giprorybflot, 1982, 14 p.