Almost all major oil fields of the Republic of Tatarstan are at the last stage of development. Maintaining the current level of hydrocarbon production requires availability of reserves. TATNEFT extensively considers the opportunities for company capitalization growth, particularly by means of bringing into development production targets that previously have been of no commercial interest due to complex recovery mechanisms. Such targets are confined, for example, to Devonian carbonate sediments occurring from the Zavolzhskian through the Sargaevskian horizons.

The article analyzes the current resource base status based on reserve volumes estimated by different methods using the example of Semilukskian-Mendymskian carbonates within the pilot area of the Romashkinskoye oil field. Out of dozens globally used resource assessment methods, three methods were considered. These are Russian Classification of Reserves (Russian Federation Ministry of Natural Resources), probabilistic-statistical method (Monte Carlo method) and United Nations Framework Classification. Russian Reserves Classification is based on volumetric method. It is the primary method for companies that carry out exploration activities in Russia, as it is applicable for estimation of resources with any reservoir drive mechanism and any category of reserves. The volumetric method relies on determination of oil or free gas volume at standard conditions of reservoir rocks. Monte Carlo method is based on probabilistic-statistical assessment of resources with account of geological risks. It enables consideration of the effects of several parameters selected during sensitivity analysis on the outcomes and statistical assessment of project perspectives. Application of probabilistic models allows to consider the uncertainty of resource assessment at early exploration stages and assess a viability of promising areas and fields development. United Nations Framework Classification is intended for determination of environmental and social-economic viability and technical feasibility of development projects and assessment of reliability of estimated future production data. It is concluded that improved accuracy of reserves estimates and continuous engagement of prospective resources requires a broad-minded approach and application of different resource estimation methods.

References

1. Fortunatova N.K., Shvets-Teneto-Guriy A.G., Petersil’e V.I., Geological report: “Otsenka perspektiv neftegazonosnosti otlozheniy domanikovogo tipa na territorii Volgo-Ural’skoy neftegazonosnoy provintsii” (Assessing the prospects for oil and gas potential of Domanik-type deposits in the territory of the Volga-Ural oil and gas province), Moscow: Publ. of VNIGNI, 2017, 892 p.

2. United Nations Framework Classification of Resources: updated version 2019, URL: 1922546_R_ECE_ENERGY_125_WEB.pdf (unece.org)

3. Shevchenko E.V., Russian and Canadian standarts for the reporting of solid mineral resources and mineral reserves: Comparative analysis (In Russ.), Gornyy informatsionno-analiticheskiy byulleten’, 2013, no. 5, pp. 358-368.

4. Lutfullin A.A., Bachkov A.P., Ibragimov U.V. et al., Geologicheskaya otsenka privlekatel’nosti vneshnikh aktivov za predelami Respubliki Tatarstan veroyatnostnym metodom s tochki zreniya obespechennosti zapasami (Geological assessment of the attractiveness of external assets outside the Republic of Tatarstan by a probabilistic method in terms of reserves), Collected papers “Geologiya i innovatsii. Problemy i puti ikh resheniya” (Geology and innovations. Problems and ways to solve them), Proceedings of scientific and practical conference dedicated to anniversaries of M.M. Ivanova and S.A. Sultanov, Bugul’ma, 21 oct. 2022, Bugul’ma: Publ. of TatNIPIneft’, 2022, pp. 52-61.

5. Khisamov R.S., Safarov A.F., Kalimullin A.M., Dryagalkina A.A., Estimation of reserves and resources using Monte-Carlo method in uncertainty module of Roxar RMS software (In Russ), Neftyanaya provintsiya, 2018, no. 3, pp. 1-17, DOI: https://doi.org/10.25689/NP.2018.3.1-17

6. Shatrov S.V., Kotenev YU.A., Discretizing probability distributions in multi-scenario evaluation of oil and gas exploration assets (In Russ.), Neftegazovoe delo, 2015, V. 13, no. 3, pp. 22-29.

7. Shpilman A.V., Klassifikatsiya neftegazovykh resursov KNR (GB/T 19492-2020) i svyazuyushchiy dokument s ramochnoy klassifikatsiey OON (UNFC 2019) (China Oil and Gas Resources Classification (GB/T 19492-2020) and Linking Document to the UN Framework Classification (UNFC 2019)), URL: https://gkz-rf.ru/sites/default/files/news_docs/lekciya_knr_shpilman_a.v.pdf?ysclid=lkwiqmtgz6872541608

Interpretation of nuclear magnetic resonance (NMR) logs enables estimation of oil viscosity from the spectrum of spin-spin relaxation times. By now, several empirical and correlation equations have been proposed for this purpose. However, the range of resultant oil viscosities is extremely broad, suggesting that the proposed equations do not include factors that determine the mechanism of viscosity formation. The article focuses on the search for such factor. For a number of high-viscosity oil samples the temperature dependence of viscosity was estimated and Arrhenius dependence parameters, such as viscosity prefactor η0 and activation energy, were calculated. Spin-spin relaxation measurements characterized by T2 spin-spin relaxation time spectra were conducted for the same samples. A rheological and widely used energy models were considered to relate T2 relaxation time spectrum to dynamic viscosity. For a rheological model with viscous elements connected in series, the relationship between viscosity and average spin-spin relaxation time, calculated from the area under relaxation decay, is demonstrated. For energy model of viscosity formation an interpretation based on averaging of energy barriers is proposed. A generalization of the energy model was proposed to result in power-law relationship between the average logarithmic spin-spin relaxation time and measured viscosity. Validity of rheological, energy, and expanded models for viscosity estimation from spin-spin relaxation time spectrum characteristics was analyzed. It is demonstrated that viscosity estimated based on average logarithmic time of spin-spin relaxation should be corrected for η0 prefactor. This correction significantly reduces the range of correlation coefficient variations in viscosity estimates based on spectrum of spin-spin relaxation times.

References

1. Dzhafarov I.S., Syngaevskiy P.E., Khafizov S.F., Primenenie metoda yadernogo magnitnogo rezonansa dlya kharakteristiki sostava i raspredeleniya plastovykh flyuidov (Application of the method of nuclear magnetic resonance to characterize the composition and distribution of reservoir fluids), Moscow: Khimiya Publ., 2002, 437 p.

2. Zega J.A., Spin-lattice relaxation in normal alkanes at elevated pressures, Houston, Texas, 1990, 123 p.

3. Morriss C.E., Freedman R., Straley C. et al., Hydrocarbon saturation and viscosity estimation from NMR logging in the Belridge Diatomite, Proceedings of SPWLA 35th Annual Logging Symposium 1994, Tulsa, Oklahoma, US, 1994.

4. Morriss C.E., Freedman R., Straley C. et al., Hydrocarbon saturation and viscosity estimation from NMR logging in the Belridge Diatomite, The Log Analyst, 1997, V. 38, pp. 44-59.

5. Zhang Q., Lo S.-W., Huang C.C. et al., Some exceptions to default NMR rock and fluid properties, Proceedings of SPWLA 39th Annual Logging Symposium, May 26-28, 1998, Keystone, Colorado, US, 1998.

6. Abragam A., The principles of nuclear magnetism, Clarendon Press, Oxford, 1961.

7. Aleksandrov I.V., Teoriya magnitnoy relaksatsii. Relaksatsiya v zhidkostyakh i tverdykh nemetallicheskikh paramagnetikakh (Theory of magnetic relaxation. Relaxation in liquids and solid nonmetallic paramagnets), Moscow: Nauka Publ., 1975, 399 p.

8. Schkalikov N.V., Skirda V.D., Archipov R.V., Solid-like component in the spin-spin NMR-relaxation of heavy oils, Magnetic Resonance in Solids, 2006, V. 8, no. 1, pp. 38-42.

9. Korb J-P., Vorapalawut N., Nicot B., Bryant R.G., Relation and correlation between nmr relaxation times, diffusion coefficients, and viscosity of heavy crude oils, Journal of Physical Chemistry C, 2015, V. 119 (43), pp. 24439-24446, DOI: https://doi.org/10.1021/acs.jpcc.5b07510

10. Bryan J., Kantzas A., Bellehumeur C., Using low field NMR to predict viscosities of crude oils and crude oil emulsions, SPE-77329-MS, 2002, DOI: https://doi.org/10.2118/77329-MS.

11. Bryan J., Mirotchnik K., Kantzas A., Viscosity determination of heavy oil and bitumen using NMR relaxometry, Journal of Canadian Petroleum Technology, 2003, V. 42, no. 7, pp. 29-34, DOI: https://doi.org/10.2118/03-07-02

12. Hirasaki G.J., Lo S.W., Zhang Y., NMR properties of petroleum reservoir fluids, Magnetic Resonance Imaging, 2003, V. 21, no. 3-4 (April-May), pp. 269-277, DOI: https://doi.org/10.1016/S0730-725X(03)00135-8

13. Freedman R., Heaton N., Fluid characterization using nuclear magnetic resonance logging, Petrophysics, 2004, V. 45, no. 3 (May-June), pp. 241-250.

14. Akkurt R., Bachman N., Minh C.C. et al., Nuclear magnetic resonance comes out of its shell, Oilfield review, Schlumberger, 2008-2009, V. 20, no. 4, pp. 4-68.

15. Maklakov A.I., Skirda V.D., Fatkullin N.F., Samodiffuziya v rastvorakh i rasplavakh polimerov (Self-diffusion in solutions and melts of polymers), Kazan’: Publ. of Kazan University, 1987, 224 p.

The article describes injection well placement method used in generation of oil field development scenarios within the scope of Epsilon software package development. This method is an improved modification of previously implemented algorithms for selection of project injection well locations. Epsilon (version 1.1) implements two algorithms for selection of project injection well locations from a set of points rejected during creation of the closest-spacing irregular pattern for project production wells due to geological or economic considerations. The first branch-and-bound optimization algorithm implies selection of a limited number of project injection well locations from the set of rejected points with account of constraints. These constraints include the minimum and maximum distance to drilled or project production wells, the presence of responding wells, and the effects on a limited maximum number of responding wells. The second algorithm provides for iterative subdivision of the entire production target area into squares of a given area and search for candidates for conversion to injection from "rejected" project locations within each square. Both algorithms, applied one after the other, yield a comprehensive set of project injection wells located at a certain spacing from project production wells. The resulting set of locations is used for project injection well placement in all field development scenarios generated in Epsilon software package through distribution of project production wells by years of planning (5-year horizon). At the same time, for voidage replacement purposes in high-rate production zones, characterized by decreasing reservoir pressures, some wells from a generated set of project injection wells should be brought to injection. Control of reservoir pressure, which is one of the most important factors contributing to energy potential of the productive formation, is of utmost importance. Reservoir pressure control entails identification of low and excess voidage replacement zones and monitoring the number of put into service/shut-in injection wells. The presented method enables: a) consideration of drilled and project production wells brought in and out of operation by forecast years; b) consideration of reservoir energy state as of the forecast year; c) conversion of idle and drilled wells brought out of operation to injection; d) planning of shutting-in of drilled and project injection wells.

References

1. Certificate of state registration of a computer program no. 2022666813 RF. Epsilon 2.0, Authors: Latifullin F.M., Sattarov Ram. Z., Khafizov R.R., Sharifullina M.A.

2. Nasybullin A.V., Razzhivin D.A., Latifullin F.M. et al., Optimization of project wells’ placement using software module for oil production and economic analysis (In Russ.), Neftyanaya provintsiya, 2018, no. 4, pp. 163-174, DOI: https://doi.org/10.25689/NP.2018.4.163-174

3. Zvezdin E.Ju., Mannapov M.I., Nasybullin A.V. et al., Stage-wise optimization of project well pattern using oil reserves evaluation program module (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2019, no. 7, pp. 28–31, DOI: https://doi.org/10.24887/0028-2448-2019-7-28-31

4. Latifullin F.M., Yartiev A.F., Sattarov Ram.Z. et l., Poisk optimal’nykh resheniy po rasstanovke proektnykh tochek bureniya dlya povysheniya rentabel’nosti razrabotki neftyanykh mestorozhdeniy (Search for optimal solutions for the placement of design drilling points to increase the profitability of oil field development), Proceedings of TatNIPIneft’, 2019, V. 87, pp. 44-51.

5. Latifullin F.M. , Sharifullina M.A., Latifullin F.F. et al., Determination of proposed injection well locations in Epsilon software package (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2023, no. 3, pp. 74-76, DOI: https://doi.org/10.24887/0028-2448-2023-3-74-76

Kynovian-Pashian reservoir section is the primary production target of the unique Romashkinskoye field and contains the field’s largest oil reserves. The whole production target is divided to 21 individual development areas by injection well rows. These areas differ in size, geological structure, confinement of key strata to different parts of the section, productivity and rates of development. The article presents the order of drilling out of individual areas, their geological structure, heterogeneity, the structure of recoverable reserves by reservoirs and groups of reservoirs. The scoring method was used to analyze the geological factors that produced the most pronounced effect on oil reserves recovery efficiency. This method relies on a set of parameters that characterize peculiar geological aspects intrinsic to each area. Displacement efficiency, that is the relative volume of fluid produced due to water injection, was assumed as technological impact factor. Production performance data are provided as well as current oil recovery factors plotted versus the ratio of injected volume to pore volume for each area. Based on obtained oil recovery factors, the areas are subdivided into several groups: high-performance, efficient, sufficiently efficient, medium- and low-performance. Effects of various parameters on oil production are analyzed. Correlation analysis suggests that oil recovery factors obtained in different areas of the Romashkinskoye field fully conform to geological structure of the reservoirs and applied development systems, production performances completely agree with geological and physical characteristics of the areas, and operating parameters. Graphical forecast oil production data for all areas of the field are provided until the end of development period.

References

1. Blinov A.F., Diyashev R.N., O roli geologicheskikh parametrov i tekhnologicheskikh upravlyayushchikh faktorov pri razrabotke neftyanykh mestorozhdeniy (On the role of geological parameters and technological control factors in the development of oil fields), Collected papers “Kontrol’ i regulirovanie razrabotki, metody povysheniya nefteotdachi plastov – osnova ratsional’noy razrabotki neftyanykh mestorozhdeniy” (Control and regulation of development, methods of enhanced oil recovery - the basis for the rational development of oil fields), Proceedinds of All-Russian meeting on the development of oil fields, Almetyevsk, June 5-9, 2000 - Almetyevsk, 2000, Part 1, pp. 153-171.

2. Diyashev R.N., Blinov A.F., The analysis of performance of development of Devonian sediments at Romashkinskoye deposit areas in view of geological and technological factors (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2006,no. 3, pp. 94-99.

3. Khisamov R.S., Shelepov V.V., Baziv V.F., Blinov A.F., Comparative estimation of the effectiveness of implemented system of development at Romashkinskoye field areas (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2010, no. 7, pp. 24-28.

4. Baziv V.F., Lisovskiy N.N., Mal’tsev S.A. et al., Sopostavitel’naya otsenka effektivnosti realizuemykh sistem razrabotki neftyanykh mestorozhdeniy v svyazi s prognozom KIN (Comparative assessment of the effectiveness of the implemented systems for the development of oil fields in connection with the forecast of oil recovery factor), Collected papers “Opyt razvedki i razrabotki Romashkinskogo i drugikh krupnykh neftyanykh mestorozhdeniy Volgo-Kamskogo regiona” (Experience in exploration and development of Romashkinskoye and other large oil fields in the Volga-Kama region), Proceedings of Scientific and practical conference dedicated to the 50th anniversary of the discovery of Devonian oil from the Romashkinskoye field, Leninogorsk, March 17-18, 1998, Kazan: Novoe Znanie Publ., 1998, pp. 37-62.

5. Baziv V.F., Ekspertno-analiticheskaya otsenka effektivnosti sistem razrabotki neftyanykh mestorozhdeniy s zavodneniem (Expert-analytical evaluation of the effectiveness of oil field development systems with waterflooding), Moscow: Publ. of VNIIOENG, 2007, 393 p6

6. Blinov A.F., Kul’mamirov A.L., Sopostavitel’nyy analiz effektivnosti razrabotki Abdrakhmanovskoy i Minnibaevskoy ploshchadey Romashkinskogo mestorozhdeniya (Comparative analysis of the development efficiency of the Abdrakhmanovskaya and Minnibaevskaya areas of the Romashkinskoye field), Proceedings of TatNIPIneft’, 2016, V. 84, pp. 43-51.

To-date, more than 60% of the world production comes from complex-structure carbonate reservoirs; also, a considerable part of the Volga-Ural petroleum play reserves is in carbonates. Carbonate reservoirs are characterized by a wide range of project recovery factor values, from 0.15 to 0.50. A common technique to improve well performance is acid fracturing. This method can only be used in acid-soluble formation, such as carbonates. A fracturing fluid is injected into the formation under a pressure higher than formation breakdown pressure, which produces a build-up in wellbore pressure leading to fracturing of the rock. Acid is then injected to react with the rock and to etch the surface of the induced fracture. Etching results from non-uniform dissolution of the rock, which, in its turn, is controlled by a number of factors, including variations in permeability and porosity, complex mineral composition (presence of both limestone and dolomites), turbulent flows in the acid-etched fracture. The rough surface of the created fracture is thus the main mechanism to maintain the fracture open during the well life, while in the alternative proppant fracturing, proppant is used to prevent fracture from closing. In acid fracturing, a large number of parameters are used to determine the efficiency of the induced fracture in terms of conductivity, including the amount of the dissolved rock, the etch pattern, the proppant occasionally used to maintain the fracture open. A 3D acid fracturing simulator is an essential tool to predict and to evaluate the acid-etched fracture performance and to safeguard against geological risks.

This paper discusses studies to improve the efficiency of mathematic modeling of acid etching and the use of model studies results for development of tools for acid fracturing engineering in PJSC TATNEFT.

References

1. Nierode D.E., Williams B.B., Characteristics of acid reaction in limestone formations, SPE-3101-PA, 1971, DOI: https://doi.org/10.2118/3101-PA

2. Roberts L.D., Guin J.A., A new method for predicting acid penetration distance, SPE-5155-PA, 1975, DOI: https://doi.org/10.2118/5155-PA

3. Lo K.K., Dean R.H., Modeling of acid fracturing, SPE-17110-PA, 1989, DOI: https://doi.org/10.2118/17110-PA

4. Settari A., Modeling of acid-fracturing treatments, SPE-21870-PA, 1993, DOI: https://doi.org/10.2118/21870-PA

5. Settari A., Sullivan R.B., Hansen C., A new two-dimensional model for acid-fracturing design, SPE-73002-PA, 2001, DOI: https://doi.org/10.2118/73002-PA

6. Romero J., Gu H., Gulrajani S.N., 3D transport in acid-fracturing treatments: Theoretical development and consequences for hydrocarbon production, SPE-72052-PA, 2001, DOI: https://doi.org/10.2118/72052-PA

7. Mou J., Zhu D., Hill A.D., Acid-etched channels in heterogeneous carbonates—a newly discovered mechanism for creating acid-fracture conductivity, SPE-119619-PA, 2010, DOI: https://doi.org/10.2118/119619-PA

8. Oeth C.V., Hill A.D., Zhu D., Acid fracture treatment design with three-dimensional simulation, SPE-168602-MS, 2014, DOI: https://doi.org/10.2118/168602-MS

9. Aljawad M.S., Schwalbert M.P., Zhu D., Hill A.D., Guidelines for optimizing acid fracture design using an integrated acid fracture and productivity model, SPE–191423-18IHFT-MS, 2018, DOI: https://doi.org/10.2118/191423-18IHFT-MS

10. Aljawad M.S., Zhu D., Hill A.D., Temperature and geometry effects on the fracture surfaces dissolution patterns in acid fracturing, SPE-190819-MS, 2018,

DOI: https://doi.org/10.2118/190819-MS

11. Ugursal A., Schwalbert M.P., Zhu D., Hill A.D., Acid fracturing productivity model for naturally fractured carbonate reservoirs, SPE-191433-18IHFT-MS, 2018,

DOI: https://doi.org/10.2118/191433-18IHFT-MS

12. Alsulaiman M., Aljawad M., Schwalber M. et al., Acid fracture design optimization in naturally fractured carbonate reservoirs, SPE–200619-MS, 2020,

DOI: https://doi.org/10.2118/200619-MS

13. Nierode D.E., Kruk K.F., An evaluation of acid fluid loss additives retarded acids, and acidized fracture conductivity, SPE–4549-MS, 1973,

DOI: https://doi.org/10.2118/4549-MS

14. Meyer B.R., Design formulae for 2-D and 3-D vertical hydraulic fractures: model comparison and parametric studies, SPE–15240-MS, 1986,

DOI: https://doi.org/10.2118/15240-MS

15. Deng J., Mou J., Hill A.D., Zhu D., A new correlation of acid-fracture conductivity subject to closure stress, SPE–140402-MS, 2011,

DOI: https://doi.org/10.2118/140402-MS

16. Cleary M.P., Analysis of mechanisms and procedures for producing favourable shapes of hydraulic fractures, SPE–9260-MS, 1980,

DOI: https://doi.org/10.2118/9260-MS

Aqueous solution of sodium silicate (sodium silicate liquid) has found wide application as a component of low silicate drilling muds, polymer salt drilling fluids, mixed silicate products and water control compositions for well construction and workover operations in PJSC TATNEFT. The term “liquid silicate” or “water glass’ refers to aqueous alkali silicate solutions regardless of cation type (sodium, potassium, lithium, ammonium), silica concentration, its polymer structure and production method. The interest to liquid-silicate-based materials is attributable to their favorable properties, availability, low cost of raw materials, environmentally friendly production and application processes, non-flammable, nontoxic nature. However, application of commercial sodium silicate solutions is challenging because liquid-state chemical product is stored in 200-liter barrels and can freeze at low temperatures, while solution water content makes 50%. Liquid product poses challenges during transportation (additional handling facility requirements), application (heavy containers) and batching. It also increases logistics footprint due to the need to dispose of used containers. Application of dry non-aqueous sodium silicate, in turn, is technologically unfeasible because of poor solubility in water under normal conditions (dissolution of sodium silicate occurs at temperatures of as high as 80-90°C). Laboratory studies on applicability of hydrated sodium silicate as technological alternative to liquid silicate has been conducted to provide evidence of drilling performance enhancing capabilities of the former and its advantages over liquid silicate: major material content of 80-90%; water content up to 20%; bulk form, no caking tendency, any allowable storage temperature; good solubility in cold water.

References

1. Sharonov L.V., Geological structure and formation conditions of the Saraylinskaya strata of Tataria (In Russ.), Tatarskaya neft’, 1957, no. 1, pp. 21-23.

2. Aksenova N.A., Ovchinnikov V.P., Burovye promyvochnye zhidkosti (Drilling fluids), Tyumen: Publ. of TSOGU, 2008, pp. 134-146.

3. Karimov M.F., Burenie neustoychivykh argillitov s primeneniem ingibirovannogo burovogo rastvora (Drilling unstable mudstones using inhibited drilling fluid), Proceedings of Scientific and Technical Conference dedicated to the 60th anniversary of TatNIPIneft, 13-14 April 2016, Naberezhnye Chelny: Publ. of Ekspozitsiya Neft’ Gaz, 2016, p. 288.

4. Li J., Experimental study and application prospect on alkali metal silicate in the process of drilling (In Russ.), Neftegazovoe delo, 2012, no. 3, pp. 81–91.

5. Akhmadishin F.F., Karimov M.F., Mironov D.A. et al., Ukreplenie argillitov pri burenii skvazhin s pomoshch’yu silikatnoy vanny (Strengthening mudstones when drilling wells using a silicate bath), Proceedings of TatNIPIneft’, 2020, V. 88, pp. 184-187.

6. Mironov D.A., Belovskaya O.S., Karimov M.F., Burovye praktiki, povyshayushchie kommercheskuyu skorost’ bureniya (Drilling practices that increase commercial drilling speed), Proceedings of TatNIPIneft’, 2018, V. 86, pp. 246-250.

7. Karimov M.F., Mironov D.A., Zamalieva R.R., Issledovaniya gidratirovannogo silikata natriya dlya primeneniya v tekhnologii ustanovki silikatnykh vann (Studies of hydrated sodium silicate for use in the technology of installation of silicate baths), Proceedings of TatNIPIneft’, 2021, V. 89, pp. 223-230.

8. Akhmadishin F.F., Karimov M.F., L’vova I.V., Zinina I.A., Opyt primeneniya izoliruyushchikh smesey pri burenii skvazhin (Experience in the use of insulating mixtures in well drilling), Proceedings of TatNIPIneft’, 2014, V. 82, pp. 220-224.

Large fields of TATNEFT PJSC, at their current stage of development, are characterized by oil production decline, deterioration of reserves structure and ever-increasing water cut of production wells. This is attributable to depletion of active oil reserves with the resultant increase in the share of residual oil trapped in unswept zones and oil reserves physically or chemically bound to reservoir rock. Complex geological structure of major production intervals, characterized by substantial permeability heterogeneity, results in water flow primarily to high-permeability interlayers, thus leaving low-permeability reservoir zones partially or completely unflushed. Regardless of natural oil production decline in the Republic of Tatarstan, particularly at the Romashkinskoye oil field, TATNEFT has succeeded not only in stabilization of oil production, but also in boosting the current production rates. This was made possible due to application of efficient field development technologies based on contour waterflooding, bringing into active development of hard-to-recover reserves, and large-scale implementation of enhanced oil recovery (EOR) methods. Application of chemical EOR methods aimed to control conformance of injection wells, redistribute fluid flows and reduce water cut of produced fluid is one of the efficient solutions to improve production performance of complex fields, especially at late stages of development. Despite abundance of available methods and chemical compositions, only a few of them proved beneficial in terms of production and economic performance. These are polymer compositions, suspensions, sedimentation and gelling compositions and hydrophobic emulsion systems. Injection of gelling, dispersion, and sedimentation compositions can completely block high- and medium-permeability reservoir intervals that contain considerable residual oil reserves despite high water saturation. This puts such intervals out of operation for a long time to the extent that they become non-producing. In light of the above, development and implementation of EOR technologies allowing for selective, partial or complete, temporary shut-off of water flow to high-permeability flushed zones to redistribute the injected water to low and medium-permeability reservoir zones is of utmost importance.

References

1. Patent RU 2379326 C1, Water repellent emulsion for oil reservoirs treatment, Inventors: Ibatullin R.R., Amerkhanov M.I., Rakhimova Sh.G., Beregovoy A.N., Andriyanova O.M., Khisamov R.S.

2. Beregovoy A.N., Amerkhanov M.I., Rakhimova Sh.G., Vasil’ev E.P., Application of invert emulsions enhances conformance in heterogeneous formations (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2010, no. 8, pp. 116-118.

3. Patent RU 2613975 C1, Invert emulsions emulsifier, Inventors: Sakhabutdinov R.Z., Beregovoy A.N., Rakhimova Sh.G., Andriyanova O.M., Fadeev V.G., Amerkhanov M.I., Nafikov A.A

4. Patent RU 2660967 C1, Method of treating non-uniform permeability oil reservoir by injection of invert emulsion, Inventors: Zaripov A.T., Beregovoy A.N., Rakhimova Sh.G., Medvedeva N.A., Lakomkin V.N., Amerkhanov M.I., Nafikov A.A.

5. Zaripov A.T., Beregovoy Ant.N., Knyazeva N.A. et al., Development and application of emulsion-based technologies to enhance production from Tatneft PJSC assets (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2019, no. 7, pp. 40-43, DOI: https://doi.org/10.24887/0028-2448-2019-7-40-43

6. Patent RU 2778501 C1, Method for developing an oil reservoir that is heterogeneous in terms of permeability, Inventors: Beregovoy A.N., Knyazeva N.A., Afanas’eva O.I., Belov V.I., Razumov A.R.

7. Patent RU 2748198 C1, Method for development of oil reservoir heterogeneous in permeability, Inventors: Zaripov A.T., Beregovoy A.N., Knyazeva N.A., Rakhimova Sh.G., Belov V.I.

One of the primary causes of sucker rod pump failures is valve clogging with solid particles, asphalt, resin and paraffin deposits, floating debris, etc. To restore pump serviceability, some remedial actions are taken involving back flushing of downhole pumping equipment. However, back flushing is not always successful due to settling out of suspended solids in the pump and loss of flush fluid into the formation. The existing equipment is not suitable for direct flushing of valves, while the pumping equipment being in use allows for bottomhole treatment without workover crew only in wells equipped with insert pumps. The developed sucker rod pump design allows for direct flushing of standing and travelling valves, as well as bottomhole treatment with no involvement of workover crews. Employment of such equipment results in increased mean time before failure and reduced operating expenses for well servicing. Field trials involving use of sucker rod pumps suitable for direct flushing have been performed in six TATNEFT wells. Pumping unit serviceability has been checked in two operating regimes: process fluid injection through direct pump flushing and activating pump flow while checking valves for leaks. The article describes the sucker rod pump design and principle of its operation, as well as presents the results of field trials in six TATNEFT wells confirming its operational capability.

References

1. Patent RU 2715130 C1, Sucker-rod pump with possibility of direct flushing (Versions), Inventors: Garifov K.M., Kadyrov A.Kh., Glukhoded A.V., Balboshin V.A., Rakhmanov I.N., Siraev M.D.

2. Catalog: Izhevsk Oil Engineering Plant. Deep rod pumps, Izhevsk, 2009, 149 p., URL: http://www.tdneftemash.ru/files/gshn.pdf

3. Catalog: Backwash valve, URL: http://oilprom-synergy.ru/submersibleequipment/577-klapany-obratnye-s-funktsiej-pryamoj-promyvki-shok-p/415-klapanyobratnye-s-funktsiej-pryamoj-promyvki-shok-p

Current development of process equipment targets to find the best solutions to reduce duration of well intervention operations relative to the number of well workovers from 91 to 80 hours per job by 2030. Analysis of well servicing costs saving potential has revealed several disadvantages of the existing flanged connections including complexity, labor intensity and long duration of assembling. Another drawback is poor reliability by reason of failure to provide uniform tightening of the nuts on studs to produce pressure-tight flanged connections without using special tools to ensure specified tightening force of connections. In light of the above, improved flange bolting designs have been developed.  

TatNIPIneft’s engineers have developed flange bolting for producing wells differing in the number of fasteners and grade of the manufacturing material. These flange boltings are suitable for various types of wellhead assemblies used in TATNEFT’s producing wells. The new flange bolting reduces labor intensity of assembly operations and improves flange bolting reliability to eliminate loss of their function, particularly the necessity to regularly tighten the nuts due to segmented elements on the stud bolts, which being in contact, prevent their spinning. The apparent benefits of the flange bolting under consideration include reduced duration of assembly and disassembly, as well as reliability and versatility. The new flange bolting has been successfully tested in six producing wells. It is recommended to be added to TATNEFT’s best practices.

References

1. Сборник унифицированных норм времени на текущий ремонт скважин: НМД 293-06-553-2016, ЕРБ 01-893-1.0-2016 (Collection of unified norms of time for current workover of wells: NMD 293-06-553-2016, ERB 01-893-1.0-2016), Альметьевск: Publ. of PJSC TATNEFT, 2016, pp. 37–40.

2. Patent RU 2753224 C1, Flange connection of wellhead equipment (Options), Inventors: Зиятдинов Р.З., Насрыев Р.И.

3. Patent RU 2760446 C1, Method for fastening a flange connection with studs with segment elements and a device for its implementation, Inventor: Зиятдинов Р.З.

4. Birger I.A., Iosilevich G.B., Rez’bovye i flantsevye soedineniya (Threaded and flanged connections), Moscow: Mashinostroenie Publ., 1990, 388 p.

One of structural elements of a well equipped with an electrical submersible pump (ESP) is wellhead assembly. It is intended to provide a positive seal around tubing string and power cable entry point into the well. The main requirement to the stuffing box for ESP wellhead penetrator is to ensure pressure integrity of inlet assembly. Leakage of production fluids and gas shall be eliminated. Stuffing box for ESP wellhead penetrator shall withstand the pressure applied by associated gases and water-oil emulsion inside the casing - tubing annulus as well as potential seasonal temperature drops. There are numerous options for sealing the ESP power cable at the wellhead. However, they all share a major disadvantage. Particularly, they all require cable stripping, which increases the risk of cable core insulation damage during installation activities, such as stuffing box packing, pumping tee installation and other operations. At subzero temperatures, the polyethylene outer sheath of power cable cores tends to crack at minor deformations. The routine practice of ESP penetrator sealing applied in TATNEFT entails unwinding the outer armor of ESP power cable, installation (packing) of stuffing box, sealing of the stuffing box by turning the sealing cap. This process is time-consuming (in fact it can take about 1 hour) and is associated with the risk of cable elements damage and premature equipment failure. In light of the above, a fundamentally new wellhead penetrator design and sealing method have been developed to eliminate the need for cable armor stripping and provide the following advantages: a) reduced penetrator installation time; b) assembly/disassembly provided by maintenance crews and operator; c) elimination of well fluid and gas leakage to the surface; d) withstanding pressures created by associated gases and water-oil emulsion during well operation; f) independence of seasonal temperature drops; e) minimized metal consumption.

The article examines the main events of the last decade affecting the global development of the world economy and energy, as a result of which significant changes have taken place and ideas about the prospects, rates and proportions of the development of world energy, about the role of certain primary energy carriers in the future energy supply of mankind. It is shown that in most of the forecasts considered, it is emphasized that the two crises of recent years – Ukrainian and energy – lead to the need for downward revision of forecasts of global GDP and energy demand, since the rapid rise in prices for them directly or indirectly affected all countries of the world. Special attention is paid to the analysis of the works of the world's leading analytical and predictive centers, in which their authors try to assess the role of the Russian oil industry in a fundamentally changed world over the past two years. Their analysis shows that there is currently no clear idea of the consequences for the Russian oil industry of the events of 2022-2023. It is shown that the most complete estimates of these events are present in the work of the IEA WEO-2022, which is analyzed in the article in the most detail. The IEA experts are confident that the long-term prospects of the Russian oil and gas complex will be weakened by both uncertainty about demand and limited access to international capital and technology, so Russian exports of fossil fuels will never return to the levels observed in 2021. Accordingly, Russia's share in international trade in oil and gas will significantly decrease by 2030. At the same time, the IEA recognizes that, despite the sanctions already in place and the reduction of Russian exports to the EU, the total volumes of Russian oil production and exports have not significantly decreased so far. BP experts come to similar conclusions, noting that formal and informal sanctions both on Russian oil imports and on the country's access to Western technologies and investments have the most significant impact on the possibilities of Russian oil production in the near future. However, experts of the OPEC Secretariat, based on the same conditions (the conflict over Ukraine, sanctions, embargoes, the withdrawal of a number of international oil companies with their technologies), see the prospects for oil production in Russia differently. It is concluded that, at least in the coming years, the volume of production and export of Russian oil will be determined not so much by the sanctions policy of "unfriendly states" as by the policy of OPEC+. Therefore, in the near future, we should expect further adjustments in the views of representatives of the world's leading analytical and predictive centers on the future of Russian oil.

References

1. Mastepanov A.M., What does the coming day have in store for us? Oil prospects in long-term forecasts for global energy development (In Russ.), Neft' Rossii, 2017, no. 7–8, pp.11–19.

2. Energeticheskiy byulleten', 2013, no. 5, URL: https://ac.gov.ru/files/publication/a/508.pdf

3. World Energy Outlook 2022. OECD/IEA, 2022, URL: –https://www.iea.org/reports/world-energy-outlook-2022

4. bp Energy Outlook 2023, URL: https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/energy-ou...

5. World Oil Outlook 2022, URL: https://www.opec.org/opec_web/en/publications/340.htm

6. IEEJ Outlook 2023, URL: https://eneken.ieej.or.jp/data/10974.pdf

7. Energy Transition Report. Energy Scenarios. Rystad Energy. November 2022, URL: https://www.rystadenergy.com/news/note-from-the-ceo-november-2022

8. World energy Transitions Outlook 2023, URL: https://www.irena.org/Publications/2023/Jun/World-Energy-Transitions-Outlook-2023

9. APEC Energy Demand and Supply Outlook 8 Edition 2022, V. 2, URL: https://aperc.or.jp/file/2022/9/27/APEC_Outlook_8th_Edition-Volume_2.pdf

10. Energy Outlook February 2023, URL: https://atradius.us/reports/economic-research-energy-outlook-february-2023.html

11. ING. 2023 Energy Outlook, URL: https://think.ing.com/uploads/reports/Energy_Outlook_-_Dec_22.pdf

12. KAPSARC. Oil Market Outlook (KOMO). Q1, 2023, URL: https://www.kapsarc.org/research/publications/kapsarc-oil-market-outlook-komo-8/

13. Russia’s War on Ukraine, URL: https://www.iea.org/topics/russias-war-on-ukraine

14. Oil 2023 Analysis and forecast to 2028, URL: https://iea.blob.core.windows.net/assets/6ff5beb7-a9f9-489f-9d71-fd221b88c66e/Oil2023.pdf

A course for sustainable development has firmly entered into the planning of economic flows of both entire states and companies, including oil and gas companies. The approach based on Environmental, Social, and Corporate Governance (ESG) is sewn by corporations into their internal strategies, so that they can not only competently manage their non-financial risks, but also gain advantages in the field of «green» financing. In the article ESG strategy is considered on the example of Gazprom PJSC. For Gazprom PJSC, which was one of the first to adopt an Environmental Policy in 1995, the priority areas are steady economic development and growth of the Company's profitability, provided that natural resources are reproduced and social support of the population. The features of management and corporate governance allow the Company to successfully implement environmental and social policy due to the internal regulations adopted. The adaptation of Gazprom's business model to the low-carbon trend is to reduce greenhouse gas emissions by burning an equivalent amount of fuel, as well as through the implementation of corporate energy saving and energy efficiency programs. The criteria for internal evaluation of the effectiveness of Gazprom's environmental programs are corporate goals adopted relative to the base year 2018. The most important areas of the Company's activities within the framework of social management are ensuring the well-being of the indigenous peoples of the north and the development of the regions of presence. Gazprom's sustainable development agenda includes projects in the field of resource conservation, hydrocarbon processing, green economy, renewable energy sources, as well as low-carbon development.

References

1. Otraslevoy reyting ekologicheskoy otkrytosti. Neftegazovye kompanii. Rossiya, 2022. - Industry rating of environmental openness. Oil and gas companies. Russia, 2022),

URL: https://wwf.ru/what-we-do/green-economy/eco-transparency-rating/ngk-russia-2022

2. Reyting ESG (ESG rating),

URL: https://raexpert.ru/ratings/esg_all

3. ESG-reytingi (ESG ratings), URL: https://akmrating.ru/esgreyting

4. Otchety o deyatel’nosti v oblasti ustoychivogo razvitiya (Sustainability activity reports), URL: https://www.gazprom.ru/sustainability/sustainability-management/reports

5. GOST R ISO 14001-2016. Sistemy ekologicheskogo menedzhmenta. Trebovaniya i rukovodstvo po primeneniyu (Environmental management systems. Requirements with guidance for use),

URL: https://docs.cntd.ru/document/1200134681

6. The TPI Global Climate Transition Centre,

URL: https://www.transitionpathwayinitiative.org

7. Carbon Disclosure Project (CDP). Companies scores,

URL: https://www.cdp.net/en/companies/companies-scores

8. Golubev S.V., Renewable energy sources in energy engineering of the gas industry. Prospects and aspects of the use of res at Gazprom, PJSC’s facilities (In Russ.), Gazovaya promyshlennost’, 2016, no. 12, pp. 72–76.

This article is devoted to the analysis of the international legal status of drilling rigs, in particular, the variability of approaches to determining their legal status. In modern conditions, the approach to determining the international legal status of floating drilling rigs is determined depending on the goals and objectives of a regulatory legal document. At the same time, it is advisable to distinguish between the legal statuses of floating drilling rigs depending on the mode of their operation: the construction of wells or transportation. Floating drilling rigs are distributed all over the world, which means that any actions related to the rigs will entail legal consequences. Most countries, including the Russian Federation, classify floating drilling rigs as marine vessels. This approach is reflected in many international conventions. However, one cannot ignore the fact that at the time of well construction, drilling rigs acquire the status of "artificial island, installations, and structures." The implementation of such a dualistic approach in the perspective of the unification of international and national law is difficult today for many reasons. It is noted that conventions regulate certain issues in the areas covered by them and cannot give a comprehensive understanding of the legal status of floating drilling rigs. In addition, national legislation, including Russian, also requires improvements in terms of determining the international legal status of drilling rigs. On the territory of Russian Federation floating drilling rigs are classified as sea vessels; however, if they are moved across the border, the rigs acquire the status of "goods" and are transported as normal cargo. The Customs Code of the Eurasian Economic Union also does not make it possible to apply a dualistic approach to determining the legal status of drilling rigs and classify them as vehicles of international transportation, which can greatly simplify the procedure for moving such a category of objects as drilling rigs across the Russian border.

References

1. Proclamation 2667: Policy of the United States With Respect to the Natural Resources of the Subsoil and Sea Bed of the Continental Shelf. – URL: https://www.trumanlibrary.gov/library/public-papers/150/proclamation-2667-policy-united-states-respe...

2. Abramov N.S., Mezhdunarodno-pravovoy rezhim morskikh neftegazovykh platform (International legal regime of offshore oil and gas platforms): thesis of candidat of legal sciences, Moscow, 2017.

3. Danil'tsev M.A., International legal status of the floating drill rigs (In Russ.), Vestnik Sankt-Peterburgskogo universiteta. Seriya 14. Pravo, 2011, no. 4, pp. 76–80.

One of the promising areas of exploration is entering new territories. One of the examples of poorly studied, but promising areas of Eastern Siberia is the Pre-Patom regional trough. At the moment, only a few hydrocarbon oilfields have been discovered within the Nyuya-Dzherba depression of the Pre-Patom regional trough, the productivity of which is established in the deposits of the Vendian-Lower Cambrian oil and gas complex, although the high prospects of this area are not in doubt.

Using the example of the Otradninskoye oilfield, located in the junction zone of the Nyuya-Dzherba depression and the Vilyuchanskaya saddle, complex overthrust nappe structures are shown, the formation of which took place under the influence of multidirectional tectonic movements. Their geological structure was influenced not only by subhorizontal movements, but also by subvertical ones overlaid on them. On the one hand, they contributed to overthrust the large blocks of the sedimentary cover, and on the other hand, they limited their distribution. Seismic survey data can reveal only large thrust dislocations. As a rule, the results of drilling in the zones of thrust dislocations show that the errors in the picks of reflecting horizons traced from seismic data are greater than the calculated accuracy of structural constructions, and reach 70-100 m. The section of subsalt deposits of the Cambrian within the dislocated part is characterized by a complex wave pattern, the interpretation of which is significantly difficult due to the presence in the section of many subhorizontal thrust dislocations with subvertical faults overlaid on them. To clarify the geological structure of this thrust zone, successive paleoprofiling was performed based on detailed well-log correlation, which confirms the presence of three or more repetitions of the section or its parts in individual wells. As a result, a consedimentary subvertical fault of the Vendian terrigenous complex was revealed in the underlying deposits, which subsequently manifested itself as a postsedimentary one. It is noted that the modern overthrust nappe structures in the Otradninskaya zone was formed in several stages. Initially, the Vilyuchanskaya saddle and the Nyuya-Dzherba depression experienced differently directed subvertical tectonic movements. The subhorizontal movements of the blocks that occurred later formed a complex multilevel thrust structure, the distribution boundary of which was a vertical fault formed in the Vendian time. The last stage was the vertical downward movement of the central part of the Otradninskaya structure.

References

1. Shemin G.G., Moiseev S.A., Stanevich A.M. et al., Perspektivy neftegazonosnosti regional’nykh rezervuarov Predpatomskogo regional’nogo progiba (Sibirskaya platforma) (Prospects for the oil and gas potential of regional reservoirs of the Cis-Patom regional trough (Siberian platform)), Novosibirsk, Publ. of SB RAS, 2018, 315 p.

2. Gayduk V.V., Cheshuychato-nadvigovaya struktura Nyuysko-Dzherbinskoy vpadiny (The scaly-thrust structure of the Nyuya-Dzherba depression), Collected papers “Problemy poiskov, razvedki i razrabotki mestorozhdeniy nefti i gaza v Yakutii” (Problems of prospecting, exploration and development of oil and gas fields in Yakutia), Yakutsk: Publ. of Yakut Scientific Center SB RAS, 1993, pp. 30–45.

3. Regional’naya stratigraficheskaya skhema kembriyskikh otlozheniy Sibirskoy platformy. Resheniya Vserossiyskogo stratigraficheskogo soveshchaniya po razrabotke regional’nykh stratigraficheskikh skhem verkhnego dokembriya i paleozoya Sibiri (Regional stratigraphic scheme of the Cambrian deposits of the Siberian Platform. Decisions of the All-Russian Stratigraphic Conference on the Development of Regional Stratigraphic Schemes of the Upper Precambrian and Paleozoic of Siberia): edited by Sukhov S.S., T.V. Pegel', Shabanov Yu.Ya., Novosibirsk: Publ. of SNIIGGiMS, 2021, 138 p.

4. Gutman I.S. et al., Korrelyatsiya razrezov skvazhin slozhnopostroennykh neftegazonosnykh ob»ektov i geologicheskaya interpretatsiya ee rezul’tatov (Correlation of well sections of complex oil and gas objects and geological interpretation of its results), Moscow: ESOEN Publ., 2022, 336 p.

5. Migurskiy A.V., Efimov A.S., Starosel’tsev V.S., New trends of petroleum exploration in Pre-Patom regional trough (Siberian platform) (In Russ.), Geologiya nefti i gaza, 2012, no. 1, pp. 21-29.

6. Migurskiy A.V., Starosel’tsev V.S., Fault zones - natural pumps of natural fluids (In Russ.), Otechestvennaya geologiya, 2000, no. 1, pp. 56–59.

The Western Kuban trough, the water area of the Azov and the Eastern Black Seas are still among the few underexplored hydrocarbon basins. Their oil and gas potential is directly due to the properties of the sedimentary strata that fill them, which are controlled by the sources of drift: quartz-rich sands and sandstones are good oil reservoirs, and clay strata are oil source complexes. Despite the long history of geological and geophysical studies of the Northern Black Sea region and the abundance of factual material accumulated in this region, there are still significant gaps in understanding the mechanism and history of basin filling and their Cenozoic geodynamic evolution. In particular, the issue of demolition source for strata of different ages has not been resolved. The demolition source for sands and sandstones could only be the complexes of the East European Platform, i.e. for the formation of high-quality oil reservoirs in the indicated basins, sedimentation flows into these basins from the north, and not from the south (regions of the modern Caucasus), are favorable. The article presents an analysis of existing ideas about the tectonic nature of the Western Kuban trough and paleogeographic reconstructions of the Northern Black Sea region using seismostratigraphic profiles and the results of U-Pb dating of detrital zircon grains (dZr) from sedimentary sequences. Highly detailed seismic records for the Western Ciscaucasia show that the flow of clastic material towards the western part of the modern mountain structure of the Greater Caucasus from the north continued until the end of the Miocene. That is, there is currently no seismostratigraphic evidence for the existence of a mountain structure in the western part of the modern Greater Caucasus up to the beginning of the Pliocene, and the uplift of this orogen in its western segment began no earlier than the Late Miocene. The existing data of U-Pb dating of dZr from the sequences of the Northern Black Sea region of different ages also did not reveal any signs of the input of erosion products from the Caucasus into the Western Kuban trough. For most of its existence, the Ciscaucasian trough had a marginal continental (“pericratonic”) nature and was filled mainly with sedimentary flows from the East European Platform. Its transformation into a foothill sedimentary basin occurred no earlier than the Pliocene. Revision of the basic ideas about the method of filling and geodynamic evolution of the Ciscaucasian trough will inevitably lead to the correction of numerical models of generation-accumulation hydrocarbon systems of the Western Kuban trough.

References

1. Gusev G.S., Mezhelovskiy N.V., Gushchin A.V. et al., Tektonicheskiy kodeks Rossii (Tectonic Code of Russia), Moscow: GEOKART: GEOS Publ., 2016, 240 p.

2. Arkhangel’skiy A.D., Usloviya obrazovaniya nefti na Severnom Kavkaze (Conditions for oil formation in the North Caucasus), Moscow – Leningrad: Scientific Publishing Bureau of the Oil Industry Council, 1927, 186 p.

3. Kerimov V.Yu., Yandarbiev N.Sh., Mustaev R.N., Kudryashov A.A., Hydrocarbon systems of the Crimean-Caucasian segment of the Alpine folded system (In Russ.), Georesursy = Georesources, V. 23(4), pp. 21–33, DOI: https://doi.org/10.18599/grs.2021.4.3

4. Nikishin A.M., Wannier M., Alekseev A.S. et al., Mesozoic to recent geological history of southern Crimea and the Eastern Black Sea region, In: Tectonic Evolution of the Eastern Black Sea and Caucasus: edited by Sosson M., Stephenson R.A., Adamia S.A., Geological Society, London, Special Publications, 2015, V. 428,

DOI: http://doi.org/10.1144/SP428.1

5. Nikishin A.M., Okay A., Tuysuz O. et al., The Black Sea basins structure and history: new model based on new deep penetration regional seismic data. Part 1: Basins structure and fill, Marine and Petroleum Geology, 2015, V. 59, pp. 638–655, DOI: 10.1016/j.marpetgeo.2014.08.017

6. Nikishin A.M., Okay A., Tuysuz O. et al., The Black Sea basins structure and history: New model based on new deep penetration regional seismic data. Part 2: Tectonic history and paleogeography, Marine and Petroleum Geology, 2015, V. 59, pp. 656–670, DOI: 10.1016/j.marpetgeo.2014.08.018

7. Aleksandrova G.N., Kuznetsov N.B., Sheshukov V.S. et al., The first results of U–Pb dating of detrital zircons from the Oligocene of the southeastern part of the Voronezh anteclise and their importance for paleogeography (In Russ.), Doklady RAN. Nauki o Zemle = Doklady Earth Sciences, 2020, V. 494,no. 1, pp. 14-19,

DOI: 10.31857/S2686739720090042.

8. Popov S.V., Antipov M.P., Zastrozhnov A.S. et al., Sea level fluctuations on the northern shelf of the Eastern Paratethys in the Oligocene – Neogene (In Russ.), Stratigrafiya. Geologicheskaya korrelyatsiya, 2010, V. 18, no. 2, pp. 99–124.

9. Popov S.V., Akhmet’ev M.A., Lopatin A.V. et al., Paleogeografiya i biogeografiya basseynov Paratetisa (Paleogeography and biogeography of the Paratethys basins), Chast’ 1. Pozdniy eotsen–ranniy miotsen (Part 1. Late Eocene–Early Miocene), Moscow: Nauchnyy mir Publ., 2009, 178 p.

10. Patina I.S., Leonov Yu.G., Volozh Yu.A. et al., Crimea–Kopet Dagh zone of concentrated orogenic deformations as a transregional late collisional right-lateral strike-slip fault (In Russ.), Geotektonika = Geotectonics, 2017, no. 4, pp. 17–30, DOI: 10.7868/S0016853X17040063

11. Patina I.S., Popov S.V., Seysmostratigrafiya regressivnykh faz maykopskogo i tarkhanskogo kompleksov severnogo shel’fa Vostochnogo Paratetisa (Seismic stratigraphy of the regressive phases of the Maikop and Tarkhan complexes of the northern shelf of the Eastern Paratethys), Collected papers “Tektonika i geodinamika Zemnoy kory i mantii: fundamental’nye problemy-2023” (Tectonics and geodynamics of the Earth’s crust and mantle: fundamental problems-2023), Proceedings of LIV Tectonic meeting, Moscow: GEOS Publ., 2023, V. 2, pp. 68–72.

12. Lithological-palaeogeographic maps of the Paratethys: edited by Popov S.V., Rögl S., Rozanov A.Y. et al., Courier Forschungs-Institut Senckenberg, 2004, V. 250, 73 p.

13. Vincent S.J., Morton A.C., Hyden F., Fanning M., Insights from petrography, mineralogy and U-Pb zircon geochronology into the provenance and reservoir potential of Cenozoic siliciclastic depositional systems supplying the northern margin of the Eastern Black Sea, Marine and Petroleum Geology, 2013, V. 45, pp. 331-348,

DOI: http://doi.org/10.1016/j.marpetgeo.2013.04.002

14. Vincent S.J., Morton A.C., Carter A. et al., Oligocene uplift of the Western Greater Caucasus; an effect of initial Arabia-Eurasia collision, Terra Nova, 2007, no. 19,

pp. 160-166.

15. Afanasenkov A.P., Nikishin A.M., Obukhov A.N., Geologicheskoe stroenie i uglevodorodnyy potentsial Vostochno-Chernomorskogo regiona (Geological structure and hydrocarbon potential of the East Black Sea region), Moscow: Nauchnyy mir Publ., 2007, 172 p.

16. Bol’shoy Kavkaz v al’piyskuyu epokhu (Greater Caucasus in the Alpine era): edited by Leonov Yu.G., Moscow: GEOS Publ., 2007, 368 p.

17. Nikishin A.M., Ershov A.V., Nikishin V.A., Geological history of the Western Caucasus and associated foredeeps based on the analysis of a regional balanced section (In Russ.), Doklady RAN. Nauki o Zemle = Doklady Earth Sciences, 2010, V. 430, no. 4, pp. 515–517.

18. Kuznetsov N.B., Romanyuk T.V., Peri-Gondwanan blocks in the structure of the southern and southeastern framing of the East European platform (In Russ.), Geotektonika, 2021, no. 4, pp. 3-40, DOI: http://doi.org/10.31857/S0016853X2104010X

19. Faccenna C., Bellier O., Martinod J. et al., Slab detachment beneath eastern Anatolia: A possible cause for the formation of the North Anatolian fault, Earth Planet. Sci. Lett., 2006, V. 242, no. 1-2, pp. 85-97, DOI: http://doi.org/10.1016/j.epsl.2005.11.046

20. Koulakov I., Zabelina I., Amanatashvili I., Meskhia V., Nature of orogenesis and volcanism in the Caucasus region based on results of regional tomography, Solid Earth, 2012, no. 3, pp. 327–337, DOI: http://doi.org/10.5194/se-3-327-2012

21. Trifonov V.G., Sokolov S.Yu., Structure of the mantle and tectonic zoning of the central Alpine-Himalayan belt (In Russ.), Geodinamika i tektonofizika, 2018, V. 9, no. 4, pp. 1127-1145.

22. Avdeev B., Niemi N.A., Rapid Pliocene exhumation of the central Greater Caucasus constrained by low-temperature thermochronometry (In Russ.), Tectonics, 2011, V. 30, pp. 1–16, DOI: http://doi.org/10.1029/2010TC002808

23. Al’mendinger O.A., Mityukov A.V., Myasoedov N.K., Nikishin A.M., Modern erosion and sedimentation processes in the deep-water part of the Tuapse trough based on the data of 3D seismic survey (In Russ.), Doklady RAN. Nauki o Zemle = Doklady Earth Sciences, 2011, V. 439, no. 1, pp. 76–78.

24. Baskakova G.V., Vasil’eva N.A., Nikishin A.M. et al., Identification of the main tectonic events by using 2D-3D seismic data in the eastern Black Sea (In Russ.), Vestnik Moskovskogo universiteta. Seriya 4: Geologiya, 2022, no. 4, pp. 21–33.

Deposits represented by carbonate reservoirs play an increasing role in the formation of the resource potential throughout the world. On the territory of the Russian Federation, one of the strategic regions for the production of hydrocarbons from carbonate reservoirs is the Nepa-Botuoba anteclise, located in the southeastern part of the Siberian Platform. In the article, the authors, as a result of summarizing a large amount of previously completed work, present search criteria for oil and gas deposits in the Osinsky productive horizon. Based on the integration of different-scale geological and geophysical material, large barrier-type carbonate structures were mapped within the considered territory of the Nepa-Botuoba anteclise, which will strengthen the geological exploration program in order to replenish the resource base. As a result of the work carried out by the authors to generalize the available material, the genesis and morphology of carbonate structures in the Osinsky horizon were determined, new lithological features of their structure were described; a forecast was given for the distribution of reservoirs with improved reservoir properties and favorable criteria for the formation of such intervals. Based on seismic data, the authors identified a fundamentally new zone, the so-called “Windows” zone, which is characterized by a change in the wave pattern, which can serve as a search criterion for zones of increased productivity. Thus, the criteria for searching for new deposits and mapping reservoir zones with improved reservoir properties have been identified, which can be used in planning geological exploration. The prerequisites for the presence of significant volumes of hydrocarbon resources have been identified, which gives hope for the discovery in the future of large or even unique oil and gas fields in the Osinsky horizon within the Nepa-Botuoba anteclise of Eastern Siberia.

References

1. Shemin G.G., Geologiya i perspektivy neftegazonosnosti venda i nizhnego kembriya tsentral’nykh rayonov Sibirskoy platformy (Nepsko-Botuobinskaya, Baykitskaya anteklizy i Katangskaya sedlovina) (Geology and oil and gas potential Vendian and Lower Cambrian deposits of central regions of the Siberian Platform (Nepa-Botuoba, Baikit anteclise and Katanga saddle)): edited by Kashirtsev V.A., Novosibirsk: Publ. of SB RAS, 2007, 467 p.

2. Kuznetsov V.G., Ilyukhin L.N., Postnikova O.V. et al., Drevnie karbonatnye tolshchi Vostochnoy Sibiri i ikh neftegazonosnost’ (Ancient carbonate strata of Eastern Siberia and their oil and gas potential), Moscow: Nauchnyy Mir Publ., 2000, 104 p.

3. Nikulina M.Yu., Myshevskiy N.V., Nikulin E.V., Classic and anomalous objects identified as a result of geological exploration at the area of Irkutsk Oil Company (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2020, no. 9, pp. 26–29, DOI: https://doi.org/10.24887/0028-2448-2020-9-26-29

4. Vorob’ev V.S., Ivanyuk V.V., Vilesov A.P., Promising zones of reservoirs development prediction in the Osin productive horizon, based on the seismic survey materials and the reconstruction of the history of geological development (In Russ.), Geologiya nefti i gaza, 2014, no. 3, pp. 3-16.

5. Plyusnin A.V., Gekche M.I., Shavarov R.D., Nikulin E.V., Geodynamic and tectonic factors for the formation and destruction of the carbonate Vendian-Cambrian hydrocarbon reserves in the southern of the Nep-Botuoba anteclise (In Russ.), Geosfernye issledovaniya = Geosphere Research, 2023, no. 1, pp. 20–35, DOI: https://doi.org/10.17223/25421379/25/2

The article discusses the features of the structure of the void space that affect the filtration properties of volcanic rocks. The features of the formation of primary and secondary void space of volcanogenic rocks are described. The primary void space is represented by shrinkage cracks, degassing voids, perlitization (in lavas), crushing cracks (in lava clastic), voids associated with loose packing of fragments (in pyroclastic), interclastic pores (in sedimentary-volcanogenic, volcanogenic-sedimentary and sedimentary rocks) . The formation of voids of secondary origin is due to tectonic, hydrothermal-metasomatic processes. Comparison of permeability and porosity characteristics of volcanogenic and sedimentary rocks is made. It is shown that a characteristic feature of volcanic rocks is the complex structure of void space. The dimensions of the voids exceed the dimensions of the channels connecting them by two or three orders of magnitude. This distinguishes volcanic rocks from sandy-argillaceous and carbonate ones, where the discrepancies in the sizes of voids and narrowings between them generally do not exceed one or two orders of magnitude. This factor predetermines the reduced filtration properties of volcanic rocks. According to the analysis of thin section images (imaging analysis), NMR studies of fully water-saturated core samples, capillary studies of volcanic rocks, significant discrepancies in the sizes of voids according to various methods were revealed, indicating a significant difference in the sizes of void bodies and channels connecting them. It is shown that with an increase in the discrepancy between the sizes of void bodies (according to image analysis) and the channels connecting them (according to capillary studies), the filtration properties decrease. Permeability increases with an increase in the size and content of filtering void channels. At the same time, in order to achieve one value of the permeability coefficient, the proportion of voids of small size should be greater than that of large ones. It is proposed to describe the relationship between the filtration and reservoir properties of volcanogenic rocks using a dumbbell model that describes the void space as an interconnected system of void bodies (macrocapillaries) and channels connecting them (microcapillaries). The model takes into account differences in the equivalent cross sections (capacitive, filtration, electrical) of macro- and microcapillaries interconnected by electrohydrodynamic analogy. It is proposed to determine the permeability of fractured volcanic rocks using empirical dependences on fracture porosity.

References

1. Maleev E.F., Vulkanity (Volcanics), Moscow: Nedra Publ., 1980, 240 p.

2. Grinberg M.E., Tsitsishvili G.K., Pore space morphology and reservoir properties of reservoir rocks and seals in the Tbilisi oil region (In Russ.), Geologiya nefti i gaza, 1988, no. 4, pp. 54–57.

3. Kondrushkin Yu.M., Tsitsishvili G.K., Krutykh L.G., Reservoir properties of effusive rocks of Muradkhanly field (In Russ.), Geologiya nefti i gaza, 1987, no. 7, pp. 35–39.

4. Krylova O.V., Razrabotka metodiki opredeleniya litologicheskogo sostava i kollektorskikh svoystv vulkanogenno-osadochnykh porod po dannym promyslovoy geofiziki (na primere sredneeotsenovykh otlozheniy mestorozhdeniy Gruzii) (Development of a method for determining the lithological composition and reservoir properties of volcanic-sedimentary rocks based on production geophysics data (on the example of Middle Eocene deposits of Georgian fields)): thesis of candidat of geological and mineralogical science, Groznyy, 1983.

5. Grinberg M.E., Papava D.Yu., Shengeliya M.I. et al., Morphology of the Middle Eocene reservoir and development features of the Samgori field (In Russ.), Geologiya nefti i gaza, 1991, no. 3, pp. 20–25.

6. Zubkov M.Yu., Pecherkin M.F., Shelepov V.V., Kriterii otsenki perspektiv promyshlennoy neftegazonosnosti krovel’noy chasti doyurskogo kompleksa Zapadno-Sibirskoy plity (Criteria for assessing the prospects for industrial oil and gas content of the roofing part of the pre-Jurassic complex of the West Siberian Plate), Collected papers “Opyt povysheniya effektivnosti razrabotki neftyanykh mestorozhdeniy Zapadnoy Sibiri” (Criteria for assessing the prospects for industrial oil and gas content of the roofing part of the pre-Jurassic complex of the West Siberian Plate), Proceedings of scientific and practical conference of geologists dedicated to the memory of Litvakov V.U., Tyumen, 1999, pp. 122–140.

7. Malinin A.V., On some possibilities of nuclear magnetic logging in geological and technological modeling (In Russ.), Karotazhnik, 2004, no. 3-4 (116–117), pp. 23–44.

8. Toporkov V.G., Rudakovskaya S.Yu., Application of nuclear magnetic resonance to evaluate petro physical parameters of oil and gas bearing rocks (In Russ.), Neft’. Gaz. Novatsii, 2013, no. 4(171), pp. 12–22.

9. Shumatbaev K.D., Kuchurina O.E., Shishlova L.M., Integrated analysis of void space in carbonates by the example of R. Trebs oil field (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2014, no. 6, pp. 91-93.

10. Sarafanova L.A., Romanov E.A., Abramova O.S., Ignat’eva T.N., Raschet petrofizicheskikh svoystv vulkanogennykh porod po rezul’tatam kapillyarnykh issledovaniy (Calculation of the petrophysical properties of volcanogenic rocks based on the results of capillary studies), Proceedings of IX scientific and practical conference “Puti realizatsii neftegazovogo potentsiala KhMAO” (Ways of realization of oil and gas potential of KhMAO), Khanty-Mansiysk, 2006, pp. 229–234.

11. Plachenov, T.G., Kolosentsev S.D., Porometriya (Porometry), Leningrad: Khimiya Publ., 1988, 176 p.

12. Akhmetov R.T., Dumbbell-like model of vacuum space of oil and gas natural reservoirs (In Russ.), Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdeniy, 2011, no. 5, pp. 31–35.

13. Tiab D., Donaldson E.C., Theory and practice of measuring reservoir rock and fluid transport properties, Oxford: Elsevier, 2004, 889 p.

14. Akhmetov R.T., Kneller L.E., Forecast for absolute permeability of granular reservoirs on the basis of the dumbbell simulation of the void space (In Russ.), Karotazhnik, 2013, no. 7 (229), pp. 75–88.

15. Boronin P.A., Gil’manova N.V., Moskalenko N.Yu., Allocation of fracturing intervals and justification of fracture parameters in the Pre-Jurassic deposits (In Russ.), Izvestiya vuzov. Neft’ i gaz, 2021, no. 1, pp. 9–19, DOI: https://doi.org/10.31660/0445-0108-2021-1-9-19

Rosneft Oil Company has been involved in the development and operation of reservoirs with a complex structure, which significantly hinders the reliability of the assessment of the wettability index of these development facilities. Wettability is one of the most important characteristics of reservoir rocks. A large number of different methods and techniques for determining this parameter have been developed, which have both their pros and cons. The use of standard research methods has certain difficulties and limitations; and in extreme cases it is completely impossible to use them in the study, for example in case of highly clayey and weakly consolidated rocks. It is obvious that the process of studying the core of complex terrigenous reservoirs faces certain difficulties, the impact of which can be reduced by using the method of nuclear magnetic resonance (NMR).

The article considers the method of NMR relaxometry on the example of weakly consolidated terrigenous rocks with low permeability (less than 0.001 μm) and high content of clay components. The method is introduced in NK Rosneft - NTC LLC (a subsidiary of Rosneft Oil Company). The obtained results were compared with the data measured by the direct method of determining the edge angle of wettability (the recumbent drop method) and the indirect centrifuge Tulbovich method. A good qualitative and quantitative convergence of the results of NMR relaxometry and the results of a direct study of the contact angle is shown. At the same time, there are significant discrepancies both at the qualitative and quantitative levels with the data obtained by the Tulbovich method, which is due to the limitations of this method. In the laboratory complex of NK Rosneft - NTC LLC" (a subsidiary of Rosneft Oil Company) a methodology for assessing wettability by NMR-relaxometry is reviewed and implemented.

References

1. Tul’bovich B.I., Metody izucheniya porod-kollektorov nefti i gaza (Methods of study of oil and gas reservoir rocks), Moscow, Nedra Publ., 1979, 199 p.

2. Borisenko S.A., Bogdanovich N.N., Kozlova E.V. et al., Estimating lyophilic properties of the Bazhenov formation rocks by adsorption and NMR methods (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2017, no. 3, pp. 12-16, DOI: https://doi.org/10.24887/0028-2448-2017-3-12-16

3. Shumskayte M.Y., Opredelenie petrofizicheskikh parametrov peschano-glinistykh obraztsov kerna i tipizatsiya plastovykh flyuidov metodom YaMR-relaksometrii (Determination of petrophysical parameters of sandy-clayey core samples and typification of formation fluids by NMR-relaxometry): thesis of candidate of technical science, Novosibirsk, 2017.

4. Churkov A.V., Rogozin A.A., Yatsenko V.M., Ignat’eva T.S., Rapid assessment of clay content based on NMR-relaxometry results (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2020, no. 9, pp. 93–95, DOI: https://doi.org/10.24887/0028-2448-2020-9-93-95

5. Rogozin A.A., Ignat’eva T.S., Churkov A.V., Integration of nmr relaxometry data and electrometric studies on the example of reservoir rocks of deposits of the Timan-Pechora oil and gas province (In Russ.), Ekspozitsiya Neft’ Gaz, 2021, no. 12, pp. 62-66, DOI: https://doi.org/10.24412/2076-6785-2021-6-62-66

Seismic data processing is an important stage of exploration works. With modern technologies, it is possible to solve many geological problems leveling shortcomings of field acquisition techniques and raw data quality. The use of advanced algorithms can significantly improve seismic processing quality and extract additional geological information from the recorded data. At the same time, an incorrect application of processing procedures can lead to a significant quality reduction and not revealing the full seismic data potential. In many cases, such situation occurs from performing only a qualitative (visual) assessment of wave field changes and its amplitude-frequency and phase characteristics. The comprehensive and objective control of processing technique in general and specific procedures application proved its extreme importance for deriving a quality output. A powerful tool here is an attribute-based quantitative analysis of seismic data quality during the entire processing cycle. In this paper, the authors show an integrated approach based on the quantitative quality control of individual procedures and interpretative support of data processing. On the example of the Pechora Sea project with processing seismic data from different-type recording equipment (bottom and towed streamers), the authors proved the effectiveness of an integrated approach to detailed control and interpretive support. The paper describes the key geological features of the area, 3D seismic acquisition parameters and the processing graph, which allowed obtaining a combined data array for subsequent complex geological and geophysical interpretation. The impact of quality control parameters changes was assessed both at various work stages and in comparison with materials of vintage data processing.

References

1. Nateganov A.A., Popov A.A., Pagliccia B., Kolichestvennyy kontrol’ kachestva: instrument dlya monitoringa obrabotki seysmicheskikh dannykh i sravneniya (Quantitative quality control: A tool for seismic data processing monitoring and comparison), Proceedings of 8th international conference and exhibition “Sankt-Peterburg 2018. Innovatsii v geonaukakh – vremya otkrytiy” (St. Petersburg 2018. Innovations in geosciences – a time of discovery), 2018.

2. Gorbachev S.V., Nikul’nikov A.Yu., Kornev A.S. et al., Advanced 3D marine seismic data processing for spatial and dynamic resolution enhancement of the Sakhalin offshore data (In Russ.) Neftyanoe khozyaystvo = Oil Industry, 2021, no. 3, pp. 40–44, DOI: https://doi.org/10.24887/0028-2448-2021-3-40-44

3. Gorbachev S.V., Titov A.B., Cherkashnev S.A., An example of planning and implementation of vertical seismic profiling in a directional well (In Russ.), Pribory i sistemy razvedochnoy geofiziki, 2022, no. 2, pp. 100-110.

4. Nikul’nikov A.Yu., Gorbachev S.V., Nurmukhamedov T.V. et al., Primenenie sistemy kolichestvennogo kontrolya i interpretatsionnogo soprovozhdeniya pri sovmestnoy obrabotke dannykh 3D buksiruemogo i donnogo oborudovaniya na shel’fe Pechorskogo morya (Application of a quantitative control and interpretation support system for joint processing of 3D data from towed and bottom equipment on the Pechora Sea shelf), Proceedings of International conference and exhibition “Geoevraziya-2022. Geologorazvedochnye tekhnologii: nauka i biznes” (Geoeurasia-2022. Geological exploration technologies: science and business), Moscow, March 30-April 1, 2022.

5. Nikulnikov A.Yu., Gorbachev S.V., Myasoedov D.N., Nurmukhamedov T.V., The application of quantitative quality control in the processing of seismic data (In Russ.), Geofizika, 2019, no. 1, pp. 55-64.

6. Araman A., Paternoster B., Isakov D., Shchukina N., Seismic quality monitoring during processing: what should we measure, Proceedings of SEG Las Vegas 2012 Annual Meeting, 2012, DOI: http://doi.org/10.1190/segam2012-1044.1

7. Paternoster B., Lys P., Crouzy E., Pagliccia B., Seismic quality monitoring during processing for reservoir characterization, Proceedings of SEG Houston 2009 international exposition and annual meeting, 2009, DOI: http:// doi.org/10.1190/1.3255213

In this article is considered an integrated approach to the study of anisotropy (vertical (VTI) and horizontal (HTI) transverse isotropy) of the medium at one of the areas of Rosneft Oil Company. The completed production cycle of the azimuthal processing of seismic data, in which the values of the azimuths of the shot point (SP) – receiver point (RP) pairs in the trace headers were saved, allows performing the azimuthal velocity analysis and further study of the resulting anisotropic (HTI) attributes. Improvement the efficiency of processing and interpretation of seismic data is one of the priority objectives of Rosneft Oil Company, therefore, today seismic exploration involves the use of a high-tech production complex. By the testing and application of advanced technologies during execution of production project, implementation of knowledge-intensive approaches to data processing, and by the uniqueness of the geological conditions during the survey related to the territory of Eastern Siberia, the realization of such a project can be confidently attributed to the promising development trends of the Company. To provide the possibility of an integrated approach to the study of medium currently actively uses wide-azimuth 3D-CDPM seismic surveys. In the case when the azimuthal processing flow is structured in advance and subsequently completely executed, when the values of the azimuths of the SP-RP pairs were stored in the data, and of course, when isotropic velocity characteristics of the medium were defined in detail, it seems possible, using mathematical complication of the parameters of the medium model, to analyze the anisotropic properties. The paper considers the types of anisotropy of the elastic medium, and shows the actual results of the works on accounting for anisotropy, performed as part of a production project at one of territory of Eastern Siberia. Among them: the results of a three-term approximation of velocities to account for VTI-anisotropy, results of pre-stack Kirchhoff time anisotropic migration, results of an elliptic approximation of velocities within the context of account HTI-anisotropy and subsequent computation the azimuthally varying velocity attributes. The article illustrates changes in the wave field after applying the procedures of accounting for anisotropy on the examples of seismograms and line of seismic cube.

References

1. Zheng Y., Seismic azimuthal anisotropy and fracture analysis from PP reflection data: thesis of PhD, Calgary: Alberta: University, 2006.

2. Winterstein D.F., Velocity anisotropy terminology for geophysicists, Geophysics, 1990, V. 55(8), pp. 1070-1088, DOI: https://doi.org/10.1190/1.1442919

3. Schoenberg M., Elastic wave behavior across linear slip interfaces, J. Acoust. Soc. of Am., 1980, V. 68, no. 5, pp. 1516–1521, DOI: https://doi.org/10.1121/1.385077

4. Voskresenskiy Yu.N., Postroenie seysmicheskikh izobrazheniy (Seismic imaging), Moscow: Publ. of Gubkin University, 2006, 116 p.

5. Narhari S.R., Al-Qadeeri B., Dashti Q. et al., Application of prestack orthotropic AVAz inversion for fracture characterization of a deep carbonate reservoir in northern Kuwait, The Leading Edge, 2015, V. 34, no. 12, pp. 1488–1493, DOI: http://doi.org/10.1190/tle34121488.1

6. Grechka V., Tsvankin I., 3-D description of normal moveout in anisotropic inhomogeneous media, Geophysics, 1998, V. 63, no. 3, pp. 1079–1092,

DOI: http:// doi.org/10.1190/1.1444386

7. Alkhalifah T., Tsvankin I., Velocity analysis for transversely isotropic media, Geophysics, 1995, V. 60, pp. 1550–1566, DOI: https://doi.org/10.1190/1.1443888

The article discusses issues related to various welltesting methods at a field in Western Siberia. Low reservoir permeability, drilling and operating horizontal wells with multi-stage hydraulic fracturing lead to a manyfold increase in the duration of well shutdowns for welltests by recording a pressure build-up curve. Thus, the main well stock cannot be covered only by welltests by recording a pressure build-up curve due to significant losses in production. At the same time, welltests conducted only on wells with a relatively low oil production rate are also less informative. Welltests with the decline analysis do not require well shutdown for evaluating the reservoir parameters. The active installation of pressure sensors at the pump suction of production wells enables carrying out the decline analysis in almost any well. Thus, an increase in the number of these welltests allows to significantly expand the research of the field. In addition, the results of the decline analysis can be used to identify the causes of production changes associated with a formation pressure decrease on the external reservoir boundary, an increase in water cut and a decrease in the productivity index. The authors show how the results of decline analysis can be used for areal analysis and localization of zones with the maximum changes in production. The causes of reservoir pressure decrease in recovery zones of the production well are discussed.

References

1. Belikov S.A., Salakhov T.R., Kardopol’tsev A.S., Leskin F.Yu., Analysis of efficiency of horizontal wells with multi-stage hydraulic fracturing on the example of Kondinskoye field (In Russ.), Neftegazovoe delo, 2023, V. 21, no. 1, pp. 39–50, DOI: https://doi.org/10.17122/ngdelo-2023-1-39-50

2. Earlougher R.C. Jr., Advances in well test analysis, SPE Monograph Series, 1977, V. 5., 264 p.

3. Lee J., Rollins J.B., Spivey J.P., Pressure transient testing, Society of Petroleum Engineers, 2003, 356 p.

4. Asalkhuzina G.F., Davletbaev A.Ya., Salakhov T.R. et al., Applying decline analysis for reservoir pressure determination (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2022, no. 10, pp. 30–33, DOI: https://doi.org/10.24887/0028-2448-2022-10-30-33

5. Certificate of official registration of a computer program no. 2023612604. Programmnyy kompleks “RN-VEGA” (Software package RN-VEGA).

6. Asalkhuzina G.F., Davletbaev A.Ya., Khabibullin I.L., Modeling of the reservoir pressure difference between injection and production wells in low permeable reservoirs (In Russ.), Vestnik Bashkirskogo universiteta, 2016, V. 21, no. 3, pp. 537–544.

7. Asalkhuzina G.F., Mirzayanov A.A., Bikmetova A.R. et al., Reservoir modeling practice and field data generalization of the spontaneous growth of induced fractures researching in linear development system (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2023, no. 7, pp. 46–50, DOI: https://doi.org/10.24887/0028-2448-2023-7-46-50

8. Davletova A.R., Fedorov A.I., Shchutskiy G.A., Risk analisys of self-induced hydraulic fracture growth in vertical plane (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2019, no. 6, pp. 50–53. – https://doi.org/10.24887/0028-2448-2019-6-50-53

Oil and gas producing companies use hydrodynamic models to predict hydrocarbon production and adopt the best development option. The choice of model type depends on the geological features of oil-saturated reservoirs and the composition of hydrocarbons in the field under consideration. The paper describes the importance of applying a dual environment model for carbonate reservoirs of high-viscosity oils, the share of world production for which is steadily increasing. An example is given on the basis of one oil field in the Samara region (hereinafter referred to as the object), which is characterized by superviscous oil and the presence of a system of fractures in carbonate deposits.

The importance of taking into account the system of fractures for carbonate reservoirs in this work is realized by comparing the results of the adaptation of single and double porosity models for the Bashkirian carbonate reservoir of the considered development object. Differences in the filtration properties of oil-saturated rocks containing a developed system of fractures in their structure are given in comparison with rocks that include only a porous structure. The single and dual media models were compared after they were adapted to the development history. The results of the history matching of models showed the need to take into account the system of fractures when creating a hydrodynamic model of carbonate reservoirs, due to the inability of the single-medium model to reproduce the actual fluid production from wells without significant adjustment of reservoir properties. In the process of adaptation, differences in the initial oil reserves were revealed. The calculation results showed that for carbonate reservoirs of super-viscous oil, filtration occurs mainly through a system of fractures, which account for most of the depleted reserves. The development of reserves from the matrix structure is difficult.

The novelty of this work is the proposed assumptions for removing uncertainties and the developed plan for adapting the dual environment model to the history of development. The obtained results show the need to apply the dual environment model in the design of the development of high-viscosity oil carbonate reservoirs. On the example of a real field, it was shown that the use of a dual-medium model makes it possible to avoid rough adaptation methods, take into account reserves in the fracture system, understand the ratio of reserves recovery from fractures and matrix and their mass transfer processes to each other, which in turn determines the development strategy and improves predictive properties of models when calculating development options.

References

1. Lucia F.J., Carbonate reservoir characterization: An integrated approach, Springer, Berlin Heidelberg New York, 2007, 333 p.

2. Dake L.P., The practice of reservoir engineering, Elsevier Science, 2001, 570 p.

3. Gurbatova I.P., Enikeev B.N., Mikhailov N.N., Elementary representative volume in the physics of a reservoir. Part 2. Scale effects and petrophysical relations (In Russ.), Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdeniy, 2018, no. 76, pp. 65–72.

4. Gurbatova I.P., Kuzmin V.A., Mikhailov N.N., Influence of pore space structure on the scale effect in studying permeability storage capacity of complicatedly built carbonate reservoirs (In Russ.), Geologiya nefti i gaza = The journal Oil and Gas Geology, 2011, no. 2, pp. 74–82.

5. Gimatudinov Sh.K., Spravochnoe rukovodstvo po proektirovaniyu razrabotki i eksplua'atsii neftyanykh mestorozhdeniy. Dobycha nefti (Reference guide to the design of the development and operation of oil fields. Oil production), Moscow: Nedra Publ., 1983, 455 p.

6. Vladimirov I.V., Andreev D.V., Egorov A.F., Impact of interaction between matrix blocks and fractures on oil stocks extraction out of fracture-porous carbonate collectors (In Russ.), Neftepromyslovoe delo, 2011, no. 5, pp. 9-12

The article deals with the phenomenon of hydraulic hammer when the pumps are stopped in the final stage of hydraulic fracturing. The authors propose a mathematical model of a fracture and a well, which are coupled at the perforation point. Both objects are considered as one-dimensional waveguides in order to take into account the possible oscillatory nature of the pressure disturbance propagation. The fracture model is considered within the Perkins – Kern – Nordgren (PKN) approach and augmented with inertial terms in the equations. The coupled model allows to obtain the pressure signal at different points in the well, taking into account the influence of the fracture. The simplified formulation of the problem, taking into account the linearisation of the equations and the absence of fluid leakage, allows to obtain analytical solutions for the fracture and the well separately. The authors discuss the principal differences between the fracture and the well as waveguides. In particular, the propagation of perturbations in the well is determined by the compressibility of the fluid and in the fracture by the elasticity of the walls. This results in a high reflection coefficient at the perforation point, so that only a small fraction of the oscillation energy is transferred from the well to the fracture and back. In addition to the oscillatory mode of perturbation propagation in the waveguide, the viscous pressure relaxation mode is possible, in which there are no oscillations. In this case, the viscosity of the fluid is the most important parameter. The oscillatory mode is only realised in the fracture when low viscosity fluid up to 30 mPa∙s is injected. In current hydraulic fracturing technology, the last stage of injection is performed on a linear gel, so the oscillatory mode is almost always realised in the well. The coupled modelling of the fracture and the wellbore is performed numerically using the control volume method. The total signal has fracture and borehole components which differ in their frequencies. The propagation of oscillations in a variable cross section fracture is discussed. In the PKN model, the crack width reduces towards the tip. In this case a combined mode of disturbance propagation is realised. This implies oscillations in the initial part of the crack and viscous relaxation in the remaining part. This leads to a change in the parameters of the fracture as a waveguide not only along its length but also in time.

References

1. Holzhausen G.R., Gooch R.P., Impedance of hydraulic fractures: Its measurement and use for estimating fracture closure pressure and dimensions, SPE-13892-MS, 1985, DOI: https://doi.org/10.2118/13892-MS

2. Carey M.A., Mondal S., Sharma M.M., Analysis of water hammer signatures for fracture diagnostics, SPE-174866-MS, 2015, DOI: https://doi.org/10.2118/174866-MS

3. Lyapidevskiy V.Yu., Neverov V.V., Krivtsov A.M., Mathematical model of water hammer in a vertical well (In Russ.), Sibirskie elektronnye matematicheskie izvestiya = Siberian Electronic Mathematical Reports, 2018, V. 15, pp. 1687–1696, DOI: https://doi.org/10.33048/semi.2018.15.140

4. Shagapov V.Sh., Bashmakov R.A., Rafikova G.R., Mamaeva Z.Z., Damped natural vibrations of fluid in a well interfaced with a reservoir (In Russ.), Prikladnaya mekhanika i teoreticheskaya fizika, 2020, V. 61, no. 4, pp. 5-14, DOI: https://doi.org/10.15372/PMTF20200401

5. Baykov V.A., Bulgakova G.T., Il'yasov A.M., Kashapov D.V., Estimation of the geometric parameters of a reservoir hydraulic fracture (In Russ.), Mekhanika zhidkosti i gaza = Fluid Dynamics, 2018, no. 5, pp. 64-75, DOI: https://doi.org/10.31857/s056852810001790-0

6. Il'yasov A.M., Bulgakova G.T., The quasi-one-dimensional hyperbolic model of hydraulic fracturing (In Russ.), Vestnik Samarskogo gosudarstvennogo tekhnicheskogo universiteta. Seriya Fiziko-matematicheskie nauki, 2016, V. 20, no. 4, pp. 739–754, DOI: https://doi.org/10.14498/vsgtu1522  

7. Economides M., Oligney R., Valko P., Unified fracture design. Bridging the gap between theory and practice, Orsa Press, Alvin, Texas, 2002, 262 p.

Hydrofluoric acid is one of the few chemicals, which could be used for alumosilicates dissolution in almost all the temperature range. These properties determine wide implementation of mud acid in oil and gas producing industry. High reactivity of mud acid also has several drawbacks such as high probability of secondary and tertiary precipitates formation in pore volume, which becomes even higher at high alumosilicate content in formation matrix and pore volume, high reactivity of these alumosilicates and high concentration of hydrofluoric acid in mud acid. All of the above factors might decrease productivity index of treated well below the productivity level achieved prior to the acid treatment. This means that pore plugging by secondary and tertiary precipitates might be more severe comparing to the pore plugging by the initial colmatants. The source of secondary and tertiary precipitates is a reaction between spent acid and remaining alumosilicates in oil or gas bearing formation. This process is forced by too high concentration of aluminum and silicon fluorides and their complexes in spent mud acid, which caused by too high reaction rate of mud acid and alumosilicates. All these facts require design and production of novel retarded fluoro-based acid systems able to complex aluminum and silicon soluble compounds to reduce their hydrolysis rate for implementation in highly reactive formations. The article presents the results of implementation of specifically designed organic mud acid system.

References

1. Palazzo A., van der Merve J., Combrink G., The accuracy of calcium-carbonate-based saturation indices in predicting the corrosivity of hot brackish water towards mild

2. Panikarovskiy V.V., Panikarovskiy E.V., Issledovaniya proniknoveniya fil’tratov tekhnologicheskikh zhidkostey v porody-kollektory (Studies of the penetration of process fluid filtrates into reservoir rocks), Moscow: Gazprom Ekspo Publ., 2009, 109 p.

3. Simon D.E., Anderson M.S., Stability of clay minerals in acid, SPE-19422-MS, 1990, DOI: https://doi.org/10.2118/19422-MS

steel, The Journal of The Southern African Institute of Mining and Metallurgy, 2015, V. 115(12), pp. 1229-1238, DOI: http:// doi.org/10.17159/2411-9717/2015/v115n12a12

4. McLeod H.O., Matrix acidizing, SPE-13752-PA, 1984, DOI: https://doi.org/10.2118/13752-PA

On the example of the Yaraktinskoye oil-gas-condensate field the problem of gypsum scaling under conditions of an abnormally high concentration of calcium ion and sulfate ion, associated with the incompatibility of reservoir and water used for flooding, is considered. The risks of salt precipitation were assessed using mathematical modeling, taking into account the physicochemical properties of mixed waters at different ratios and thermobaric conditions. The study of the component composition of deposits from wells and oilfield communications was carried out using X-ray phase analysis. A forecast of the possible amount of gypsum formed by claster pad of the Yaraktinskoye field was made based on the data on geological modeling of reservoir fluid flows and the composition of produced water as a result of mixing reservoir and injected waters - water of the Litvitsevsky formation, reservoir brine and fresh water. The adaptation of technologies for the removal and prevention of gypsum scaling to the objects of the Yaraktinskoye deposit are shown: two-stage technologies for treating the bottomhole formation zone – alkaline-acid conversion of gypsum deposits, inhibition of gypsumprecipitation in wells, technologies for preliminary discharge of produced water from a well, the ionic composition of which introduces the main incompatibility in flow of produced fluids. Further prospects for the development of technologies to combat gypsum scale for the conditions of the Yaraktinskoye field are outlined.

References

1. Salikhov R.M., Chertovskikh E.O., Gil'mutdinov B.R. et al., Special aspects of chemical reagents use under high mineralization of produced waters (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2020, no. 9, pp. 59–62, DOI: https://doi.org/10.24887/0028-2448-2020-9-59-62

2. Salikhov R.M., Gil'mutdinov B.R., Folomeev A.E., Kononov M.I., Control of gypsum formation in the “well-formation-surface equipment” system (In Russ.), Inzhenernaya praktika, 2023, no. 2, pp. 4–10.

3. Kashchavtsev V.E., Dytyuk L.T., Zlobin A.S., Kleymenov V.F., Bor'ba s otlozheniem gipsa v protsesse razrabotki i ekspluatatsii neftyanykh mestorozhdeniy (Control of gypsum deposits during the development and operation of oil fields), Moscow: Publ. of VNIIOENG, 1976, 63 p.

4. Lutfullin A.A., Abusalimov E.M., Folomeev A.E. et al., Complex matrix treatment technologies selection and adaptation for the injection wells of the Republic of Tatarstan oilfields (In Russ.), Georesursy, 2022, V. 24(4), pp. 91–101, DOI: https://doi.org/10.18599/grs.2022.4.8.

5. Maksimov G.L., Promakhov V.A., Fedotova A.V., Perov K.A., The use of pipelines made of alternative materials at the fields of INK LLC. Application results. Analysis, development prospects (In Russ.), Inzhenernaya praktika, 2022, no. 3, pp. 54 – 65.

The article demonstrates the examples of the material factors as well as typical research methods for determining the contribution of these material factors to the reliability and durability of oil and oil products pipeline transport facilities. Among the most common material factors are the following: dependence of the actual material properties on the duration of operation and operating conditions (increase in strength characteristics; drop in ductility and viscosity characteristics); change in local properties of facilities in the areas of defects; failure to perform the routine modes of thermomechanical processing of pipe products during their production; the presence of anisotropy of the properties of the material of structures in various directions; increased contamination of metal with non-metallic inclusions and their groups and accumulations (low metallurgical quality); presence of structural sections with actual characteristics different from the rest part of the structure; presence of significant residual stresses; low cyclic properties; deviation of chemical composition parameters from the requirements of regulatory documentation for products. The actual characteristics of the material used in the manufacture of the structure are also an important factor determining the reliability of oil and oil products pipeline transport structures (pipes, tanks, connecting parts of pipelines, mechanical and engineering equipment). Both the low values of these characteristics and the available deviations from the regulatory or design parameters can shorten the life of the structure or result in its sudden failure. Actual characteristics of metal in the structures are used as basic values (input data) for calculation of strength and durability of operation of structures with defects. Each of the above-mentioned material factors shall, to one degree or another, be comprehensively studied and taken into account with a corresponding weight factor in the parameters of reliability of pipeline transport facilities operation.

References

1. Shtremel’ M.A., Razrushenie (Destruction), Moscow: Publ. of MISIS, 2014-2015, 669 p.

2. Tsenev N.K., Salikhov R.N., Kozyrev O.A. et al., T-pipe destruction origin investigation (In Russ.), Nauka i tehnologii truboprovodnogo transporta nefti i nefteproduktov = Science & Technologies: Oil and Oil Products Pipeline Transportation, 2018, V. 8, no. 3, pp. 290–299, DOI: https://doi.org/10.28999/2541-9595-2018-8-3-290-299

3. Apal’kov A.A., Odintsev I.N., Plotnikov A.S., Evaluation of the range of reliable residual stress measurements using hole drilling technique (In Russ.), Zavodskaya laboratoriya. Diagnostika materialov = Industrial laboratory. Diagnostics of materials, 2016, V. 82, no. 2, pp. 47–52

The article analyzes the effectiveness of the method for improving the rheology of paraffin oil mixture from the Atyrau – Samara main oil pipeline due to hydrodynamic pulse treatment in a rotary pulse apparatus (RPA). The processed oil was subjected to hydrodynamic pulse impact in the RPA such as pressure and flow rate pulsations, intensive cavitation, vortex formation, and large variable shear loads. The hydrodynamic pulse impact on oil in the RPA allowed, due to the destruction of internal structure, reducing the dynamic viscosity and changing the shape of the flow curves of oil sample compared to untreated oil sample. The oil samples hydro-pulse treatment efficiency was evaluated using dimensionless coefficients showing the ratios of dynamic viscosity before and after treatment, the specific power values required to maintain the oil flow in a rotary viscometer before and after physical impact on oil, and the change ratio of the oil thixotropy energy to the energy spent during treatment process. The efficiency factors of hydrodynamic pulse treatment of paraffin oil are significantly greater than unity, which justifies the prospects of the proposed method. A decrease in the viscosity of the oil mixture from the Atyrau – Samara main oil pipeline is observed more when treated at low temperatures - at 5°C. Thus, the dynamic viscosity at 5°C of the oil sample decreased by more than 1.6 times, the power of maintaining the flow in the rotary viscometer decreased by 2 times, and the efficiency factor of hydrodynamic pulse impact on oil was more than 250. The relaxation time of the rheological parameters of oil was 5 days. Preliminary preparation of thixotropic oils for pumping through main oil pipelines is a promising way to reduce energy costs of transportation.

References

1. Stepanov A.V. et al., Interaction Russian Federation and Republic Kazakhstan in field of oil transportation (Atyrau-Samara oil pipeline) (In Russ.), Vostochnaya analitika, 2019, no. 1, pp. 42–47.

2. Sunagatullin R.Z., Kutukov S.E., Gol'yanov A.I. et al., Control of oil rheological properties by exposure to physical methods (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2021, no. 1, pp. 92-97, DOI: https://doi.org/10.24887/0028-2448-2021-1-92-97

3. Ratov A.N., Mechanisms of structure formation and anomalies of rheological properties of high-viscosity oils and bitumens (In Russ.), Rossiyskiy khimicheskiy zhurnal, 1995, V. 39, no. 5, pp. 106–113.

4. Iktisanov V.A., Sakhabutdinov K.G., Rheological studies of paraffin-base oil at different temperatures (In Russ.), Kolloidnyy zhurnal = Colloid Journal, 1999, V. 61, no. 6, pp. 776-779.

5. Boytsova A.A., Kondrasheva N.K., Rheological properties of hydrocarbon systems with a high content of resins and asphaltenes (In Russ.), Inzhenerno-fizicheskiy zhurnal = Journal of Engineering Physics and Thermophysics, 2018, V. 91, no. 4, pp. 1098–1105.

6. Volkova G.I. et al., Podgotovka i transport problemnykh neftey (nauchno-prakticheskie aspekty) (Treatment and transportation of problematic oils (scientific and practical aspects)), Tomsk: Publ. of TSU, 2015, 136 p.

7. Revel'-Muroz P.A. et al., Estimation of the oil pumping technology effectiveness with drag reduction agents (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2020, no. 1, pp. 90–95, DOI: https://doi.org/10.24887/0028-2448-2020-1-90-95

8. Brand A.E., Zakirzakov A.G., Toropov S.Yu., Sokolov S.M., Hydrodynamic cavitation treatment as a way reduce the viscosity of heavy oil and efficiency transport (In Russ.), Sovremennye problemy nauki i obrazovaniya = Modern problems of science and education, 2015, no. 2–3.

9. Sawarkar A.N., Cavitation induced upgrading of heavy oil and bottom-of-the-barrel: a review, Ultrasonics Sonochemistry, 2019, V. 58, DOI: https://doi.org/10.1016/j.ultsonch.2019.104690

10. Avvaru B. et al., Current knowledge and potential applications of cavitation technologies for the petroleum industry, Ultrasonics Sonochemistry, 2018, V. 42, pp. 493–507, DOI: http://doi.org/10.1016/j.ultsonch.2017.12.010

11. Promtov M.A. et al., Change of rheological parameters of high-paraffin oil under multi-factor impact in a rotor-stator device (In Russ.), Problemy sbora, podgotovki i transporta nefti i nefteproduktov, 2020, no. 5(127), pp. 76-88, DOI: http://doi.org/10.17122/ntj-oil-2020-5-76-88

12. Kutukov S.E. et al., Improving crude oil rheology by hydro-pulse cavitation treatment (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2022, no. 3, pp. 94–98,

DOI: https://doi.org/10.24887/0028-2448-2022-3-94-98

13. Promtov M.A. et al., Effectiveness criteria for physical actions on oil with complicated rheological characteristics (In Russ.), Nauka i tehnologii truboprovodnogo transporta nefti i nefteproduktov = Science & Technologies: Oil and Oil Products Pipeline Transportation, 2022, V. 12, no. 2, pp. 128-137, DOI: https://doi.org/10.28999/2541-9595-2022-12-2-128-137

14. Promtov M.A. et al., Assessment of hydrodynamic pulse treatment method performance in improvement of rheology of oil blend from Yuzhno-Lyzhskoye and Kyrtaelskoye fields (In Russ.), Nauka i tehnologii truboprovodnogo transporta nefti i nefteproduktov = Science & Technologies: Oil and Oil Products Pipeline Transportation, 2023, V. 13, no.3, pp. 225-231.

15. Boytsova A.A. et al., Comparison of structural and mechanical properties of paraffin and naphthene-aromatic petroleum dispersed systems (In Russ.), Neftegaz.RU, 2018, no. 3, pp. 86–91.

Decommissioning is necessary in the life cycle end of any oilfield. Decommissioning issues are of particular importance for offshore fields, which pose the greatest risks to the preservation of ecological systems. Subsea pipeline infrastructure occupies a significant place in the total works of the offshore field decommissioning. In practice, a variety of the abandonment methods of the submarine pipelines can be used, from leaving in-situ to removing the pipeline completely, with the reconstruction of the previous submarine relief. Subsea pipelines decommissioning is a carefully planned in advance sequence of activities, which are the safest and most economically feasible. Submarine pipelines decommissioning is reviewed on the individually basis, using comparative analysis, whereby a decision is made on the appropriate decommissioning method. The article considers Vietsovpetro JV existing technical solutions and the milestones of the submarine pipelines decommissioning. The authors analyzed current international practices for the subsea pipelines decommissioning, in order to optimize expenses and practice application. The authors considered the pipeline mechanical cutting method by hydraulic power shear and had carried out a comparative study with the existing in Vietsovpetro JV cutting methods, based on this data the feasibility conclusions were implemented. The list of the measures proposed for Vietsovpetro JV adoption is given in order to optimize costs of the submarine pipelines decommissioning.

References

1. The abandonment of offshore pipelines. Methods and procedures for abandonment. prepared by John Brown Engineers and Constructors Ltd., 1997, 229 p.

2. Suvorova I.A., Morskie neftegazovye sooruzheniya. Vyvod iz ekspluatatsii (Offshore oil and gas facilities. Removal from service), Moscow: Publ. of Gubkin University, 2007, 110 p.

3. Ty Tkhan' Ngia, Veliev M.M., Le V'et Khay, Ivanov A.N., Razrabotka shel'fovykh neftyanykh mestorozhdeniy SP V'etsovpetro (Pryzhok “Belogo Tigra” dlinoyu v 35 let...) (Development of offshore oil fields by JV Vietsovpetro (Leap of the "White Tiger" 35 years long ...)), St. Petersburg: Nedra Publ., 2017, 386 p.