The Domanik high-carbonaceous formation rocks in the South Tatar Arch and the Melekess Depression of the Volga-Ural petroleum basin are traditionally regarded as the oil-source rocks that have either not yet entered the oil window or are at its very beginning. Analysis of the laboratory data over the recent years revealed that on the northern flank and in the central part of the South Tatar Arch, there are zones with significantly transformed kerogen. After hexane extraction of samples exhibiting a high degree of kerogen maturity, porosity values reach 6–10 %, allowing the Domanik deposits to be classified as promising unconventional reservoirs containing hard-to-recover reserves. These zones are confined to a sub-lateral belt near the northern boundary of the South Tatar Arch, to the western part of the central South Tatar Arch along the Altunino-Shunak depression, as well as to several local areas. The most probable reason for the presence of local zones with increased maturity is additional thermal heating, which could occur in areas characterized by numerous disjunctive faults during tectonic reactivation in the Carboniferous-Permian or later periods. However, presence of faults cannot be considered as the exclusive criterion for distinguishing intervals characterized by a high catagenetic maturity of Domanik organic matter. Exploration programs aimed at identification of hydrocarbon accumulations in Domanik formations should be based both on location of areas rich in organic matter and reconstruction of the tectonic history, including initiation and subsequent development of disjunctive faults.

References

1. Stupakova A.V., Fadeev N.P., Korobova N.I. et al., Criteria for oil and gas search in Domanic deposits of the Volga-Ural basin (In Russ.), Georesursy, 2015, no. 2(61),

pp. 77–86.

2. Safarov A.F., Aflyatunov R.R., Lutfullin A.A. et al., Evaluation of the resource potential of high-carbon rocks of the Saraylin series within the southeastern slope of North Tatar arch in the Republic of Tatarstan (In Russ.), Georesursy, 2025, V. 27, No. 2, pp. 243–254, DOI: https://doi.org/10.18599/grs.2025.2.18

3. Mel’nikov P.N., Varlamov A.I., Fortunatova N.K. et al., Results of quantitative estimation of unconventional oil resources of the Russian Federation (In Russ.), Geologiya i geofizika, 2024, V. 65, No. 1, pp. 8–25, DOI: https://doi.org/10.15372/GiG2023189

4. Bazhenova T.K., HC resources estimation of bituminous formations of Russian oil and gas bearing basins (In Russ.), Geologiya nefti i gaza, 2017, No. 5, pp. 37–50.

5. Varlamov A.I., Mel’nikov P.N., Poroskun V.I. et al., Unconventional oil reservoirs in high-carbon carbonate-siliceous Domanik formations, Volga-Urals Province: Results of studies and future development trends (In Russ.), Geologiya nefti i gaza, 2020, No. 6, pp. 33–52, DOI: https://doi.org/10.31087/0016-7894-2020-6-33-52

6. Tissot B.P., Welte D.H., Petroleum formation and occurrence, Springer-Verlag Telos, 1984, 699 p.

7. Tsarev V.V., Poroskun V.I., Geologicheskoe stroenie neftyanykh slantsevykh formatsiy zarubezhnykh stran (Geological structure of oil shale formations in foreign countries), edited by Varlamov A.I., Mel’nikov P.N., Moscow: Publ. of VNIGNI, 2022, 215 p.

8. Storozhenko V.D., Gazeeva F.M., Mingazutdinov A.N., Kuznetsov N.S., Kharakteristiki organicheskogo veshchestva domanikovoy vysokouglerodistoy formatsii na territorii Respubliki Tatarstan (Characteristics of organic matter of the Domanik high-carbon formation in the Republic of Tatarstan), Proceedings of TatNIPIneft’ / Tatneft’, Naberezhnye Chelny: Ekspozitsiya Neft’ Gaz Publ., 2025, V. 93, pp. 56–66.

9. Varlamov A.I., Petersil’e V.I., Poroskun V.I. et al., Technique of oil reserves estimation in Domanik deposits (In Russ.), Geologiya nefti i gaza, 2017, No. 5, pp. 51–65.

10. Galimov E.M., Is the source of hydrocarbons at the supergiant Romashkino oil field (Tatarstan) an influx from a crystalline basement or oil source sedimentary deposits? (In Russ.), Geokhimiya, 2015, No. 2, pp. 103–122, DOI: https://doi.org/10.7868/S001675251502003X

11. GOST 12113-94. Brown coals, hard coals, anthracites, solid dispersed organic matters and carbon materials. Method lor determination of reflectance Indices.

12. Jacob H., Classification, structure, genesis and practical importance of natural solid oil bitumen (“migrabitumen”), International Journal of Coal Geology, 1989, V. 11,

pp. 65–79, DOI: https://doi.org/10.1016/0166-5162(89)90113-4

13. Grigorenko T.V., Savostin G.G., Kalmykov A.G. et al., Domanic oil shale sediments organic matter and saturating fluids characteristics on the territory of the Tatarstan Republic (In Russ.), Georesursy, 2025, V. 27, No. 1, pp. 221–235, DOI: https://doi.org/10.18599/grs.2025.1.25

14. Khisamov R.S., Voytovich E.D., Liberman V.B. et al., Tektonicheskoe i neftegeologicheskoe rayonirovanie territorii Tatarstana (Tectonic and oil zoning of Tatarstan): edited by Khisamov R.S., Kazan’: FEN Publ., 2006, 328 p.

15. Gatiyatullin N.S., Baratov A.R., Liberman V.B., Oil bearing resources of Tatarstan in terms of the hypothesis of the earth degassing (In Russ.), Georesursy, 2013,

No. 1(51), pp. 17–22.

This paper discusses aspects of sedimentation and formation of Visean deposits within the north part of the western flank of the South Tatar Arch in the Republic of Tatarstan, using the Bobrikovskian terrigenous and Tulskian terrigenous‑carbonate deposits as an example. The study is based on a comprehensive interpretation of cores and well logging data using the isopach maps and 3D seismic interpretation results. Spectral decomposition slices and a number of other seismic attributes were used to update the morphology of facies. Textural and structural features of rocks developed in a certain sedimentation environment were described, ranging from quiet hydrodynamic conditions affected by high tides to active unidirectional hydrodynamics with vigorous supply of sand material, or to fluvial-dominated unidirectional hydrodynamics. Based on the core data, transitional sedimentation environments, ranging from coastal‑continental to shallow‑marine, were identified represented by deltaic macro-facies of the coastal plain: distributaries, flooding sands, deltaic marshes, silting distributaries, deltaic bays, and stream mouth bars; their correlation with the seismic responses on well logs was demonstrated. It was found that formation of complex-genesis traps in the Bobrikovskian-Tulskian deposits was governed by a combination of factors related to paleo-geographic and paleo-geomorphological sedimentation settings at that time. Facies maps were generated for the Bobrikovskian–Tulskian deposits, showing the inheritance of paleo-valley trends of the Tournaisian stage and a local transition from coastal-continental to shallow-marine environments. The obtained results enhance the reliability of geological models and prediction of reservoir zones during exploration planning on the western flank of the South Tatar Arch.

References

1. Abdullin N.G. et al., Geologicheskie usloviya formirovaniya i razmeshcheniya melkikh zalezhey nefti v paleozoyskikh otlozheniyakh Tatarii (Geological conditions of formation and placement of small oil deposits in the Paleozoic deposits of Tatarstan), Proceedings of VNIGNI, Moscow: Publ. of VNIGNI, 1983, pp. 115–121.

2. Aliev M.M., Yarikov G.M., Khachatryan R.O. et al., Kamennougol’nye otlozheniya Volgo-Ural’skoy neftegazonosnoy provintsii (Carboniferous deposits of the Volga-Ural oil and gas province), Moscow: Nedra Publ., 1975, 261 p.

3. Abdullin N.G. et al., Geologicheskoe stroenie i neftenosnost’ Vostochnoy Tatarii (Geological structure and oil potential of Eastern Tatarstan) Kazan’: Publ. of TatNIPIneft’, 1974, 192 p.

4. Baraboshkin E.Yu., Prakticheskaya sedimentologiya. Terrigennye rezervuary. Posobie po rabote s kernom (Practical sedimentology. Terrigenous reservoirs. Core handbook), Tver’: Izdatel’stvo GERS Publ., 2011, 140 p.

5. Khisamov R.S., Gubaydullin A.A., Bazarevskaya V.G., Yudintsev E.A., Geologiya karbonatnykh slozhnopostroennykh kollektorov devona i karbona Tatarstana (Geology of carbonate complex reservoirs of Devonian and Carboniferous of Tatarstan), Kazan’: FEN Publ., 2010, 283 p.

6. Mukhametshin R.Z., Paleovrezy i ikh rol’ v osvoenii trudnoizvlekaemykh zapasov nefti (Paleoincisions and their role in the development of hard-to-recover oil reserves), Moscow: Geoinformmark Publ., 2006, 80 p.

The paper presents a method for evaluation of void space structure of terrigenous and carbonate rocks based on the concept of hydraulic reservoir types. The study aims to determine the effective pore size distribution, which influences the anisotropy of reservoir properties. Results of laboratory studies and layer-by-layer description of core samples from the South Tatar Arch were used to determine the regularities in the distribution of pore space structure (equivalent diameter) with secondary transformations (dolomitization, recrystallization, leaching, fracturing, stylolization, etc.) and lithological features (Dunham lithotypes) for Kizelovian carbonate reservoirs. To gain the understanding of effective pore throat sizeт distribution, an approach relying on estimation of average equivalent pore and pore throat size using porosity factor and Flow Zone Indicator is proposed. Histogram analysis enabled determination of cut-off values for equivalent pore throat size for Tournaisian carbonate reservoirs. The resultant cut-off values and identified dependencies enabled generation of three-dimensional distribution models of secondary transformations to reflect anticipated void space alteration zones in carbonate reservoirs. Application of updated and
detailed geological model improved the history matching process of reservoir simulation model and, thus, increased the accuracy of simulated forecast data. It is demonstrated that the concept of hydraulic flow units combined with
lithotypes distribution and secondary transformations, provides an efficient tool for a more detailed description and differentiation of the void space in carbonate reservoirs.

Interwell tracer test method is a direct tool for studying fluid flows from injection wells and determining the reservoir properties within the interwell space. However, due to poor efficiency of reservoir pressure maintenance system owing to the geological aspects of development targets with hard-to-recover reserves, tracer test results do not always enable to come up with appropriate system improvement solutions. Standard results of tracer studies of the reservoir pressure maintenance system are aimed primarily at acquisition of high-quality data suggesting the presence or absence of interwell communication. Due to specific geological aspects of carbonate reservoirs and in most cases relatively short-time tracer tests, standard quantitative interpretation does not provide sufficient information pertaining fluid flow behavior in the interwell space and reservoir sweep characteristics. These factors require additional analytical efforts to improve the information content and applicability of resultant data. The study demonstrates the need to use reservoir energy state data, as well as current geological and production factors that may have critical impact on the system. Combination of historical data and field test results ensures better understanding of the effects of interwell space characteristics and well operation conditions on currently maintained reservoir pressure, as well as the efficiency of reserves depletion in carbonate reservoirs. Research findings enabled setting up a program aimed to improve waterflood performance and reduce nonproductive injection.

References

1. Muslimov R.Kh., Nefteotdacha: proshloe, nastoyashchee, budushchee (optimizatsiya dobychi, maksimizatsiya KIN) (Oil recovery: Past, Present and Future (production optimization, maximization oil recovery), Kazan’: Fen Publ., 2012, 663 p.

2. Budkevich R.L., Belova T.T., Alen’kin I.A., Control over filtration zones and coverage coefficient based on tracer studies of the interwell space (In Russ.), Neftyanaya provintsiya, 2024, No. 3, pp. 96–109, DOI: https://doi.org/10.25689/NP.2024.3.96-109

3. Trofimov A.S., Berdnikov S.V., Krivova N.R. et al., Summary of indicator (tracer) studies at deposits in Western Siberia (In Russ.), Territoriya Neftegaz, 2006, No. 12, pp. 72–77.

4. Sanni M., Abbad M., Kokal S. et al., A field case study of an interwell gas tracer test for gas-EOR monitoring, SPE-188363-MS, 2017,

DOI: https://doi.org/10.2118/188363-MS

5. Kamyshnikov A.G., Beregovoy Ant.N., Zaripov A.T. et al., The interwell tracer test method for early water flooding diagnostics and risk mitigation during infill drilling

(In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2025, No. 7, pp. 36-39, DOI: https://doi.org/10.24887/0028-2448-2025-7-36-39

Due to various factors, the share of hard-to-recover oil reserves (HTRR) tends to increase. Significant volumes of HTRR are concentrated in oil deposits with lithologically trapped (lenticular) reservoirs. Admittedly such reservoirs have a low degree of depletion, which provides grounds for more extensive study of the problem and investigation of ways to enhance the efficiency of lens development. Primary problems of lenticular reservoir development are following: low production rates when lenses are developed by single wells; limited waterflooding, effectiveness of which depends on a number of factors (anisotropy of reservoir properties, lens size, well placement, etc.); geological heterogeneity (variation of lithological composition, permeability, and porosity). The greater the heterogeneity of reservoir properties of a lenticular body, the more areas unaffected by displacement processes may remain in it by the end of development. Within a heterogeneous formation, the thickness actually affected by waterflooding is often less than the total thickness of the waterflooded formation. A large share of HTRR may remain at the edges of a lens, low-productivity reservoirs, and stagnant and dead zones. Identifying these reserves and selecting their recovery methods is one of the key tasks of an effective development strategy for developing lenses. As digital technologies advance, it became possible to calculate numerous predictive scenarios for the development of targets using hydrodynamic models. This paper presents an example of predictive calculation for the development of a lenticular area in a hydrodynamic model under several scenarios to determine the factors affecting oil production and final oil recovery factor.

References

1. Golovin N.A., Malyshev V.L., Research of features of approbation and following oil reserves in linzedic collectors (In Russ.), Bulatovskie chteniya, 2018, V. 2, Part 1,

pp. 137–143.

2. Nasybullin A.V., Teoreticheskie osnovy geologo-gidrodinamicheskogo modelirovaniya razrabotki neftyanykh mestorozhdeniy (Theoretical foundations of geological and hydrodynamic modeling of oil field development), Moscow – Izhevsk: Publ. of Institute of Computer Research, 2026, 345 p.

3. Vereskov A.I., Kanevskaya R.D., Korobkin S.V., Probabilistic description of lenticular reservoirs and uncertainty assessment on drilling (In Russ.), Geologiya i geofizika, 2005, V. 46, No. 2, pp. 160–169.

4. Minnullin A.G. et al., Experience of lenses identification in productive deposits section of Kynovsky and Pashijsky horizons of the Alkeevskaya area of Romashkinskoye field (In Russ.), Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdeniy, 2017, No. 10, pp. 40–45.

5. Zakirov S.N., Kontarev A.A., Oil recovery from lenticular reservoirs (In Russ.), Doklady akademii nauk = Doklady Earth Sciences, 2007, V. 413, No. 1, pp. 68–70.

6. Batraev S.A., Oil production from lenticular formations (In Russ.), Tendentsii razvitiya nauki i obrazovaniya, 2024, No. 108–13, pp. 105–108, DOI: https://doi.org/10.18411/trnio-04-2024-725

7. Zakirov S.N., Kontarev A.A., Development of lenticular collectors (In Russ.), Vesti gazovoy nauki, 2012, No. 2(10), pp. 73–77.

8. Balin V.P. et al., Accounting of a formation compartmentalization when calculating areal sweep efficiency (In Russ.), Neftepromyslovoe delo, 2016, No. 1, pp. 14–20.

9. Marmylev I.Yu., Clarification of the geological structure by determining the features of the localization of undeveloped reserves (In Russ.), Neftyanik poles’ya, 2024, No. 1(45), pp. 122–127.

10. Khisamutdinov N.I. et al., Modeling of oil recovery from anisotropic layer under various regimes of deposit (CO) development (In Russ.), Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdeniy, 2010, No. 1, pp. 5–7.

11. Samoylov M.V. et al., Experience of mathematical modeling of oil resources extraction out of lens-type formations (In Russ.), Neftepromyslovoe delo, 2012, No. 11, pp. 76–81.

12. Vladimirov I.V., Galin E.R., Technology of development of lythologically screened «lens» used by a separate well (In Russ.), Oborudovanie i tekhnologii dlya neftegazovogo kompleksa, 2011, No. 2, pp. 22–29.

13. Medvedev K.Yu., Prospects for the application of non-stationary waterflooding to increase the production of oil reserves (In Russ.), Nauka. Innovatsii. Tekhnologii, 2017, No. 2, pp. 147–158.

Super-viscous oil and natural bitumen of the Permian formations in the Republic of Tatarstan represent a strategic resource of the Russian oil industry. However, their development is impossible without thermal and chemical enhanced oil recovery (EOR) methods. Typically, performance of EOR methods is assessed by displacement efficiency and dynamic viscosity of the produced fluid, but geochemical properties of the residual oil are studied rarely. The paper presents the results of a comparative study of residual bitumoid in the bituminous sandstone core samples after a set of 13 flow tests using a linear reservoir model, including treatment by saturated and superheated steam, steam in combination with hydrocarbon solvent, carbon dioxide under subcritical conditions, and an aquathermolysis catalyst. Bitumoid was extracted from core samples using organic solvents, and its geochemical properties were determined by SARA-analysis and gas chromatography-mass spectrometry. The majority of the considered EOR methods yielded a similar reduction in the bitumoid content of the rock, whereas some differences in the alteration of fractional composition were observed. For example, steam treatment results in a shift of the n-alkane series toward high-molecular-weight components, while its combination with the solvent enhances the resin-asphaltene fraction recovery efficiency. Under subcritical conditions, CO2 effectively interacts with cyclic and heteroatomic compounds. Catalytic aquathermolysis demonstrated the best performance and was additionally accompanied by degradation of asphaltenes. The obtained results showed notable differences in the mechanisms of EOR-bitumoid interaction, thus serving as a basis for the optimal selection of EOR technologies considering the initial fluid geochemical properties.

References

1. Yarakhanova D.G., Prospects for the development of heavy oil and natural bitumen by horizontal wells (In Russ.), Georesursy, 2015, V. 1, No. 3(62), pp. 53–56.

2. Nureeva N.S. et al., Aspects of development of extra-heavy oil fields on western slope of South-Tatarian Arch (In Russ.), Territoriya Neftegaz, 2016, No. 10, pp. 64–69.

3. Sitnov S.A. et al., Intensification of thermal steam methods of production of heavy oil using a catalyst based on cobalt (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2016, No. 11, pp. 106–108.

4. Bingfan Li et al., Molecular dynamics simulation of CO2 dissolution in heavy oil resin-asphaltene, Journal of CO2 Utilization, 2019, V. 33, pp. 303–310,

DOI: https://doi.org/10.1016/j.jcou.2019.06.011

5. Safina I.R. et al., Application of the SARA analysis method to characterize oil dispersed systems (In Russ.), Vestnik Kazanskogo tekhnologicheskogo universiteta, 2014, V. 17, No. 24, pp. 212–213.

6. Kontorovich A.E., Ratsional’nyy kompleks sovremennykh metodov analiza v organicheskoy geokhimii (Rational complex of modern methods of analysis in organic geochemistry), Collected papers “Sovremennye metody analiza organicheskoy geokhimii” (Modern methods of organic geochemistry analysis), Novosibirsk: Publ. of SNIIGGiMS, 1973, pp. 4–13.

7. Pengcheng Liu et al., Experimental study of the steam distillation mechanism during the steam injection process for heavy oil recovery, Journal of Petroleum Science and Engineering, 2018, V. 166, pp. 561–567, DOI: https://doi.org/10.1016/j.petrol.2018.03.096

8. Maity S.K., Ancheyta J., Marroquín G., Catalytic aquathermolysis used for viscosity reduction of heavy crude oils: A review, Energy & Fuels, 2010, V. 24, No. 5,

pp. 2809–2816, DOI: https://doi.org/10.1021/ef100230k

9. Kudryashov S.I. et al., Catalytic heavy oil upgrading by steam injection with using of transition metals catalysts (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2017, No. 8, pp. 30–34, DOI: https://doi.org/10.24887/0028-2448-2017-8-30-34

10. Patent RU2857881C1, Core holder for bulk reservoir model, Inventors: Lebedev V.N., Aflyatunov R.R., Sotnikov O.S., Khannanov M.T.

The expanding application of chemical enhanced oil recovery methods necessitates deployment of rapid, informative monitoring techniques capable of evaluating fluid flow processes and the physical-chemical interactions within the reservoir – fluid – agent system. Conventional approaches (hydrodynamic, geophysical, tracer methods) either lack sensitivity to chemical changes or require considerable expenditures coupled with time-consuming data interpretation. Well testing provides integral flow characteristics, but does not reveal the nature of interfacial phenomena. Tracer well surveys are complicated due to sorption and dispersion of tracer agents. This paper proposes a procedure for productive formation characterization based on physical and chemical properties monitoring of both the reservoir and the injected fluids. The procedure is based on the concept that such parameters as pH, electrical conductivity, ionic composition, and interfacial tension represent an integral response to the processes of mixing, flow, and interphase interaction within the formation. Monitoring can be performed in a background mode without the physical-chemical treatment, and variation of the monitored parameters will reflect changes in the natural composition of the produced fluids. Systematic analysis of variations of the above-mentioned parameters in the produced fluids in case of physical-chemical treatment enables assessment of the agent slug propagation dynamics, identification of breakthrough zones, and adjustment of treatment intensity, thereby controlling the reservoir sweep. This physical-chemical monitoring, combined with geochemical modeling and tracer surveys, improves the information content of field data and provides a basis for real-time optimization of chemical flooding strategies. The proposed approach ensures continuous data acquisition and early detection of undesirable geochemical reactions.

References

1. Porbar A.J., Afarideh H., Rashidi F., Simulation-based reservoir analysis assisted by chemical tracers transport for the development of enhanced oil recovery strategies, Scientific Reports, 2025, V. 15, DOI: https://doi.org/10.1038/s41598-025-27755-7

2. Wilt M., Alumbaugh D., Oil field reservoir characterization and monitoring using electromagnetic geophysical techniques, Journal of Petroleum Science and Engineering, 2003, V. 39, No. 1–2, pp. 85–97, DOI: https://doi.org/10.1016/S0920-4105(03)00041-X

3. Di Zhu, Binfei Li, Haifeng Li et al., Effects of low-salinity water on the interface characteristics and imbibition process, Journal of Petroleum Science and Engineering, 2022, V. 208, DOI: https://doi.org/10.1016/j.petrol.2021.109564

4. Dandekar R., Ardekani A.M., Effect of interfacial viscosities on droplet migration at low surfactant concentrations, Journal of Fluid Mechanics, 2020, V. 902,

DOI: https://doi.org/10.1017/jfm.2020.551

5. Davletbaev A.Ya., Asalkhuzina G.F., Urazov R.R., Sarapulova V.V., Gidrodinamicheskie issledovaniya skvazhin v nizkopronitsaemykh kollektorakh (Hydrodynamic studies of wells in low-permeability reservoirs), Novosibirsk: Dom Mira Publ., 2023, 176 p.

6. Wang Zhijing, Y2K Tutorial: Fundamentals of seismic rock physics, Geophysics, 2001, V. 66(2), pp. 398–412, DOI: https://doi.org/10.1190/1.1444931

7. Patidar A.K., Joshi D., Dristant U., Choudhury T., A review of tracer testing techniques in porous media specially attributed to the oil and gas industry, Journal of Petroleum Exploration and Production Technology, 2022, V. 12(10), pp. 3339–3356, DOI: https://doi.org/10.1007/s13202-022-01526-w

The paper presents key findings of coreflood experiments aimed to determine oil displacement performance of polymer solutions depending on concentration of two types of polyacrylamide (PAA) (medium- and high molecular) in presence of surfactants. Coreflooding is the most insightful method for research of mixed oil displacement compositions, enabling performance comparison at different concentrations and various physical and chemical properties, to determine the most important properties of compositions and select efficient solutions for specific conditions. The experiments were conducted under conditions typical of terrigenous Devonian and Bobrikovian sediments with permeability of core samples ranging from 0,303 to 0,726 μm2, and oil viscosity of 17,2–21,3 mPa·s for the terrigenous Devonian and 41,6–54,5 mPa·s for the Bobrikovian. The key polymer property that influences the oil displacement is viscoelasticity, which depends on concentration and molecular weight of the polymer, temperature, water salinity, permeability, and other conditions. Coreflood experiments revealed that under given experimental conditions PAA resistance to high salinity and PAA molecular weight have the largest impact on oil displacement properties of PAA solutions and surfactant-polymer compositions (with the same amount of surfactants in the composition), moreover surfactant-polymer composition ensures manyfold increase in displacement efficiency compared to PAA solution. Maximum increase in oil displacement efficiency for surfactant-polymer compositions studied under conditions typical of terrigenous Devonian and Bobrikov sediments was 29,8 % and 30,6 % respectively.

References

1. Murzakaev F.G., Maksimov G.G., Khimizatsiya neftedobyvayushchey promyshlennosti i okhrana okruzhayushchey sredy (Chemicalization of the oil industry and environmental protection), Ufa: Bashkirskoe knizhnoe izd-vo Publ., 1989, 154 p.

2. Silin M.A., Magadova L.A., Tolstykh L.I., Davletshina L.F., Khimicheskie reagenty i tekhnologii dlya povysheniya nefteotdachi plastov (Chemicals and technologies for EOR), Moscow: Publ. of Gubkin University, 2015, 145 p.

3. Khisametdinov M.R., Ganeeva Z.M., Varlamova E.I. et al., Tekhnologiya povysheniya nefteotdachi s primeneniem dispersnykh i silikatnykh kompozitsiy na mestorozhdeniyakh PAO “Tatneft’” (Enhanced oil recovery technology using dispersed and silicate compositions at the fields of PJSC Tatneft), Proceedings of TatNIPInefti / Tatneft’, Moscow: Neftyanoe khozyaystvo Publ., 2021, V. 89, pp. 164–169.

4. Khisametdinov M.R., Varlamova E.I., Shabalin N.V. et al., Use of microgel systems to increase oil recovery in highly depleted fields (In Russ.), Neft’. Gaz. Novatsii, 2024, No. 9, pp. 46–49

5. Ibatullin R.R., Tekhnologicheskie protsessy razrabotki neftyanykh mestorozhdeniy (Technological processes for the development of oil fields), Moscow: Neftyanoe khozyaystvo Publ., 2019, 321 p.

6. Khisametdinov M.R., Karimova G.R., Varlamova E.I. et al., Issledovaniya svoystv khimicheskikh produktov dlya primeneniya v tekhnologiyakh uvelicheniya nefteizvlecheniya PAO “Tatneft’” (Research of the properties of chemical products for use in technologies for enhancing oil recovery at Tatneft PJSC), Proceedings of

X International (XVIII All-Russian) Scientific and Practical Conference, Moscow, 29 June 2023, Moscow, Publ. of Gubkin University, 2023, pp. 61–64.

This paper presents an integrated approach to the targeted selection of surfactants for micellar flooding based on the example of the North-Almetyevsk area of the Romashkinskoye oil field. The main production zone is represented by the terrigenous reservoirs of Kynovian and Pashian horizons. Reservoir oil composition was thoroughly examined by chromatography–mass spectrometry, SARA analysis, and Fourier-transform IF spectroscopy. Concentration of acyclic saturated hydrocarbons is approximately 77 %. The SARA-analysis revealed prevalence of aromatic hydrocarbons (51,79 %), along with considerable amounts of resins (9,76 %) and asphaltenes (14,61 %). Fourier-transform IF spectroscopy confirmed the presence of aromatic structures, aliphatic chains, and oxygenated groups typical for resins and asphaltenes. The obtained data served as the basis for molecular modeling of the surfactant composition using the NMIRacle computing package. One-dimensional NMR spectra for 1H, 13C, and 15N nuclei, along with two-dimensional correlation spectra including HSQC, HMBC, COSY-DQF, and NOESY, were simulated. Benchmarking against the Aldrich NMR Database yielded the optimum formulation of an efficient surfactant for flooding containing linear alkylbenzenesulfonates, oleinic acid diethanolamide, and monoethanolamine. The synthesized surfactant based on the simulated composition was tested using a synthetic core characterized by permeability of 357,7·10-3 μm2, porosity of 24,92 %, and a pore volume of 7,023 ml. The predicted oil displacement efficiency increase is 13,43 %. The results of this study confirm the efficiency of the proposed surfactant selection method based on the actual composition of the reservoir oil. This approach can be used to enhance oil recovery at the late stages of field development in the Volga-Ural region.

References

1. Sandyga M.S., Rogachev M.K., Kambulov E.Yu. et al., Surfactants for flooding oil fields at a late stage of development (In Russ.), Neftegaz.RU, 2022, No. 4, pp. 30–36.

2. Xue-Zhi Zhao, Guang-Zhi Liao, Ling-Yan Gong et al., New insights into the mechanism of surfactant enhanced oil recovery: Micellar solubilization and in-situ emulsification, Petroleum Science, 2022, V. 19, No. 2, pp. 870–881, DOI: https://doi.org/10.1016/j.petsci.2021.11.014

3. Rukovodstvo po proektirovaniyu i primeneniyu metoda zavodneniya s vodorastvorimymi poverkhnostno-aktivnymi veshchestvami (PAV) (Guide to the design and application of water-soluble surfactant flooding), BashNIPIneft, 1979, 83 p.

4. Ottomano F., Li Y., Ganose A.M., NMIRacle: Multimodal generative molecular elucidation from IR and NMR spectra, URL: https://huggingface.co/papers/2512.19733

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URL: https://www.energyinst.org/industry/publications/topics/ip-test-methods/ip-469-determination-of-satu...

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DOI: https://doi.org/10.1016/j.cis.2011.09.001

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DOI: https://doi.org/10.1002/aic.10041

9. Haihua Pei, Jingling Shan, Guicai Zhang et al., Selection of optimum surfactant formulations with ultralow interfacial tension for improving the oil washing efficiency, ACS Omega, 2021, V. 6, No. 37, pp. 23952–23959, DOI: https://doi.org/10.1021/acsomega.1c02930

10. Miranda-Olvera A.D., Domínguez-Esquivel J.-M., Martinez J., Hydrophilic–lipophilic balance (HLB) correlation method for the selection of ionic liquid surfactant modifiers of the viscosity and emulsion stability of heavy oils, Langmuir, 2025, V. 41, No. 13, pp. 8753–8765, DOI: https://doi.org/10.1021/acs.langmuir.4c05309

In oil production, a drain valve is used to prevent spillage of borehole liquid onto the surface during the pulling of downhole pumping equipment. This valve connects the tubing to the annulus in wells operated by sucker rod pumps. Liquid from the tubing flows into the annulus, and the levels in them equalize. An analysis of existing liquid drainage options was performed, and their application areas and disadvantages were identified. A valve for liquid drainage from the tubing was developed for wells equipped with sucker rod pumps. The sleeve locking system is made as an elastic split ring mounted in the radial groove of the sleeve and sequentially interacting with two corresponding radial grooves provided on the inner surface of the body. Elastic seals are rigidly mounted to the sliding sleeve and the body. The tubing hole is made in the groove with bevels. The pusher rod is installed on the sucker rod between two joints and is made as a sleeve with elastic protrusions sized to secure it inside the tubing string. The elastic protrusions ensure tight fit of the pusher rod through the sleeve. The technical result is achieved through simplification of the valve, its assembly, and improvement of durability. Various types of sleeve fixation inside the body of the drain valve were studied. The material and the form of the pusher rod were selected. Acceptance tests demonstrated the effectiveness of the drain valve, and it is recommended for deployment on other wells of TATNEFT PJSC.

References

1. Mishchenko I.T., Skvazhinnaya dobycha nefti (Oil production), Moscow: Neft’ i gaz Publ., 2003, 816 p.

2. Ivanovskiy V.N., Darishchev V.I., Sabirov A.A. et al., Skvazhinnye nasosnye ustanovki dlya dobychi nefti (Well pumping units for oil production), Moscow: Neft’ i gaz Publ., 2002, 823 p.

3. Bogdanov A.A., Pogruzhnye tsentrobezhnye elektronasosy dlya dobychi nefti (raschet i konstruktsii) (Submersible centrifugal pumps for oil production (design and calculation)), Moscow: Nedra Publ., 1968, 272 p.

4. Nikishenko S.L., Neftepromyslovoe oborudovanie (Oilfield equipment), Volgograd: In-Folio Publ., 2008, 231 p.

5. Patent RU2797747C1, Valve for draining fluid from the tubing (embodiments), Inventors: Garifov K.M., Kadyrov A.Kh., Glukhoded A.V., Garaev I.G., Rakhmanov I.N., Balboshin V.A.

The need for integrated damage rating during damage assessment of sucker rods and evaluation of the conditions of their further application in repair rod strings is analyzed in terms of reliability theory of equipment operations with basic elements connection to solve the problem of implementation of operational-state-based approach to sucker rod and rod string operation. Existing maintenance performance metrics for used sucker rods were examined. The paper provides the rationale for final quality metrics for sucker rod maintenance, necessary to ensure fail-safe operation of sucker rod strings downhole, through transition from failure investigation and examination concept to prediction and prevention. An algorithm for sucker rod damage assessment during maintenance according to operational state and quality standards based on damage rate is substantiated. This should ensure the transition from localized detection of individual faults to an integrated numerical assessment of operational status and damage rate. Implementation of numerical assessment is key to development of an automated database management system of maintenance and repair data for all downhole equipment of sucker rod pumping units through elaboration of managerial decisions to ensure the balance between fail-safe run life downhole and the cost of life cycle of downhole pumping equipment considering the geological state of reserves and fluctuations in market prices of produced fluids in accordance with formally described methods of reliability theory and large-scale maintenance within unified procedures.

References

1. Klimov V.A., Valovskiy K.V., Valovskiy V.M. et al., Reducing the risk of rod breakage with improved methods of qualitative and quantitative assessment of the remaining life (In Rus.), Neftyanoe khozyaystvo = Oil Industry, 2009, No. 7, pp. 60–64.

2. Klimov V.A., Valovskiy K.V., Valovskiy V.M. et al., Improvement of downhole pumping equipment maintenance system (In Rus.), Neftyanoe khozyaystvo = Oil Industry, 2010, No. 7, pp. 52–54.

3. Klimov V.A., Valovskiy K.V., Valovskiy V.M. et al., Justifying diagnostic indicators of pump rod fatigue failure (In Rus.), Neftyanoe khozyaystvo = Oil Industry, 2009,

No. 11, pp. 126–129.

4. Klimov V.A., Valovskiy K.V., Valovskiy V.M. et al., On the physics of failures, methods of reliability calculations, and efficient performance of rod string in a well (In Rus.), Neftyanoe khozyaystvo = Oil Industry, 2011, No. 7, pp. 66–69.

5. Klimov V.A., Pishchaev D.V., Petrochenkov A.B., Bochkarev S.V., Topical issues related to efficient operation of oil production facilities (In Rus.), Neftyanoe khozyaystvo = Oil Industry, 2020, No. 7, pp. 46–49, DOI: https://doi.org/10.24887/0028-2448-2020-7-46-49

6. GOST 13877-96. Sucker rods and sucker rod couplings. Specifications

This research aims to examine the disadvantages of existing equipment and consider the features of designed blowout preventer installed at wellhead of production well equipped with two-tubing-string dual completion system. Well servicing of hazard class I and II wells necessitates reliable industrial safety control. Existing preventers are incompatible with dual-string wellhead assemblies, thus posing a risk of uncontrolled release of gas, oil, and water and resulting in failure to meet the requirements of Blowout Prevention Service of the Ministry of Emergency Situations of Russia regarding the obligatory use of blowout prevention equipment. To address the above challenges, engineers of Well Servicing Technology Sector of TatNIPIneft’s Well Operation and Workover Department improved existing preventer designs and developed wellhead sealing technologies for wells equipped with two-tubing-string downhole assembly depending on wellhead equipment type. At wellhead assembly 2ANK-50/40x2, 2ANK-40x21, 2ASHK-50/40x21 or 2ASHK-40x21, advanced double-ram blowout preventer PPS-2F-180x21-2K is used which has two levels of pipe rams, where the opening formed by the upper ram level is offset relative to the bore of blowout preventer. Modified PPShR-2F-152x21 preventer with accessories is used with AUD 50x14 or AUD 40x14 wellhead assemblies. The equipment and technology were successfully field tested in seven wells with two-tubing-string downhole assemblies. The work was presented to Technology Innovation Board and included in TATNEFT PJSC best corporate practices. The developed solutions enable compliance with industrial safety regulations and efficient servicing of dual-tubing-string dual completion wells, minimizing the risk of gas, oil, and water blowouts.

References

1. On approval of the federal norms and regulations in the field of industrial safety “Safety Rules in the Oil and Gas Industry”: Order of Rostechnadzor dated December 15, 2020, no. 534

2. Patent RU2808812C1, Bop for a well with a double-row pipe string, Inventors: Mokeev S.A., Ziyatdinov R.Z.

3. Patent RU2805701C1, Method for installing preventer on support flange of wellhead assembly and constant tripping out two-lift arrangement of downhole equipment from well and device for its implementation, Inventors: Mokeev S.A., Ziyatdinov R.Z., Makarov D.N.

The necessity of conducting tests to select corrosion-resistant paint materials suitable for application at subzero ambient and metal temperatures is driven by the need to extend the painting season, and reduce material and economic expenditures associated with the use of additional heating devices to maintain the required temperature conditions during paint application on large-sized tanks and vessels. This paper is focused on the issues of selection and testing of winter-grade paint materials available on the domestic market, which are capable of forming a long-life coating. The research involved a series of field and laboratory tests for eight corrosion-resistant coatings belonging to different chemical classes. These coatings are specifically designed to protect the inner surfaces of tanks and vessels against corrosion when applied at low ambient temperatures ranging from -5 to -10 °C. Following preparation under the specified conditions, the coated samples were subjected to a series of accelerated laboratory tests to evaluate their behavior in corrosive environments. The tests included static exposure to brine water within a wide temperature range from 20 to 80 °C, crude oil exposure, and cyclic temperature variation from 90 to -40 °C. Subsequently, changes in decorative and protective properties were evaluated, including coating film thickness, adhesion strength measured by both the X-cut and the pull-off methods, shock and abrasion resistance, and the rust creep. Based on the experimental results, a number of coating systems that demonstrated satisfactory performance during the accelerated laboratory aging tests were recommended for field application.

References

1. Agafonova G.L., Valiakhmetov R.I., Kozhaeva A.V. et al., Methodological foundations of anticorrosive protection of capacitive equipment with the use of paint and varnish coatings (In Russ.), Ekspozitsiya Neft’ Gaz, 2024, No. 8, pp. 129–133, DOI: https://doi.org/10.24412/2076-6785-2024-8-129-133

2. Agafonova G.L., Kozhaeva A.V., Experience in the use of paints and varnishes for anti-corrosion protection of oilfield equipment of Bashneft JSC (In Russ.), Territoriya Neftegaz, 2012, No. 3, pp. 40–44.

3. Revin P.O., Study of the possibility of applying protective coatings in low temperature conditions (In Russ.), Inzhenernaya praktika, 2025, No. 3–4, pp. 52–55.

4. Pavlutskaya A.S., Technologies and materials used for painting metal structures in sub-zero temperatures (In Russ.), Molodoy uchenyy, 2023, No. 29(476),

pp. 44–48.

5. Rychkov A.V., Tokarev M.D., Chernova A.A., Corrosion protection system for tank equipment adapted for climatic conditions of middle latitudes (In Russ.), Khimicheskaya fizika i mezoskopiya, 2023, V. 25, No. 4, pp. 577–586, DOI: https://doi.org/10.15350/17270529.2023.4.52

6. GOST 9.402-2004. Unified system of corrosion and ageing protection. Paint coatings. Metal surface preparation for painting.

7. GOST 31993-2024. Paint materials. Determination of film thickness.

8. GOST 9.407-2015. Unified system of corrosion and ageing protection. Paint coatings. Method of appearance rating.

9. GOST 32702.2-2014. Paint materials. Determination of adhesion by X-cuttest method.

10. GOST 32299-2025. Coating materials. Pull-off test for adhesion.

11. GOST 4765-2024. Coating materials. Method for determining of coating impact resistance.

The study is focused on the efficiency of chemical agents for hydrogen sulfide and mercaptans removal from the wellstream. The aim of the study is to establish a field-applicable procedure for hydrogen sulfide and mercaptans identification in crude oil and produced water, and to select an optimal chemical agent capable of neutralizing them in produced fluids by lowering their concentrations to 20 ppm and 40 ppm, respectively. When stimulating wells with formation fluids characterized by high hydrogen sulfide and mercaptan content, appropriate treatment techniques are applied to neutralize corrosive sulfur compounds, with determination of their concentrations as a prerequisite for ensuring safe delivery of the produced fluids to consumers. Accurate determination of hydrogen sulfide and mercaptan concentrations under the field conditions is challenging. To solve this problem, the measurement procedure № 62506-06 was tested using crude oil samples specifically for determination of the mercaptan content. Efficiency of the four samples of neutralizing agents and various oxidizers was analyzed. A relationship between hydrogen sulfide and mercaptan concentration and oil–neutralizer contact time was established. Performance of a neutralizer was evaluated during treatment of produced water and crude oil with water content of up to 5 %. The gas-liquid mixture can be disposed of in horizontal flares using different types of burners. However, crude oil flaring is prohibited during well testing, surveying, or stimulation operations. Consequently, identification of an optimum chemical agent for neutralization of hydrogen sulfide and light mercaptans in gas-liquid mixtures remains a crucial task.

References

1. MVI No. 62506-06. Neft’, nefteprodukty i uglevodorodnye gazovye kondensaty. Opredelenie serovodoroda (Oil, petroleum products, and hydrocarbon gas condensates. Determination of hydrogen sulfide), Bugul’ma: Publ. of TatNIPIneft’, 2006, 14 p.

2. Shipilov D.D., Shatalov A.N., Garifullin R.M., Solov’ev V.V., Hydrogen sulphide stripping technologies used at Tatneft’s assets (In Russ.), Neftyanaya provintsiya, 2020, No. 4, pp. 206–216, DOI: https://doi.org/10.25689/NP.2020.4.206-216

3. Ibragimov N.G., Shipilov D.D., Mingazova A.Z. et al., Application of hydrogen sulfide scavengers for oil treating at crude oil treatment facilities of Tatneft OAO

(In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2014, No. 7, pp. 52–54.

The paper investigates mechanisms for enhancing the development value of oil and gas fields with hard-to-recover reserves (HRR) under conditions of rapid growth in their share of Russia's resource base: according to Rosnedra, HRR account for approximately 52 % of the country's total oil reserves, with their production share increasing from 7,2 % in 2017 to 32 % in 2024; the Russian Ministry of Energy projects this share to exceed 80 % by 2030. The study integrates Value Management theory; Stage-Gate (Front-End Loading) standards and the AACE International cost estimate classification system. The scientific novelty comprises three contributions: extending the classic Total Project Value formula with a ΔNPVtechnology learning component that captures the value of the learning curve, critical for long-cycle HRR projects; developing a Stage-Gate with Excess Profits Tax (EPT) synergy model in which each decision gate is interpreted as an exercise point of a compound real option, with EPT parameters defining the profitability boundary; benchmarking Russia's EPT against Norway, the United Kingdom, Australia, and the United States to identify directions for improving the domestic fiscal architecture. It is established that the cumulative effect of technological, organizational, and fiscal factors enables the transition of HRR projects from marginal to sustainably profitable without increasing project risks. Aggregate EPT revenues for 2019–2025 exceeded RUB 7,9 trillion RUB.

References

1. Kontorovich A.E., Epov M.I., Eder L.V., Long-term and medium-term scenarios and factors in world energy perspectives for the 21st century (In Russ.), Geologiya i geofizika, 2014, V. 55, No. 5-6, pp. 689-700, DOI: https://doi.org/10.15372/GiG20140501

2. BS EN 12973:2020. Value Management. British Standards Institution/European Committee for Standardization.

3. Dixit A.K., Pindyck R.S., Investment under Uncertainty, Princeton: Princeton University Press, 1994, 468 p., DOI: https://doi.org/10.1515/9781400830176

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5. Trigeorgis L., Real options: Managerial flexibility and strategy in resource allocation, Cambridge, MA: MIT Press, 1996, 471 p.

6. Merrow E.W., Industrial megaprojects: Concepts, strategies, and practices for success, Hoboken, NJ: John Wiley & Sons, 2011, 384 p.

7. Cooper R.G., Stage-gate systems: A new tool for managing new products, Business Horizons, 1990, V. 33, No. 3, pp. 44–54, DOI: https://doi.org/10.1016/0007-6813(90)90040-I

8. AACE International. Recommended Practice 17R-97: Cost Estimate Classification System, Morgantown, WV, 2020 (rev.), URL: https://aheinc.ca/wp-content/uploads/2018/12/AACE-Cost-Estimate-Classification-System.pdf

9. AACE International. Recommended Practice 87R-14: Cost Estimate Classification System — As Applied in EPC for the Petroleum Exploration and Production Industries, Morgantown, WV, 2020 (rev.), URL: https://ru.scribd.com/document/652556241/87r-14

10. Khasanov M.M., Sugaipov D.A., Zhagrin A.V. et al., Improvement of capex estimation accuracy during early project stages (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2014, No. 12, pp. 22–27.

11. Khasanov M.M., Maksimov Yu.V., Skudar’ O.O. et al., Cost engineering in gazprom neft pjsc: current situation and future development (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2015, No. 12, pp. 30–33.

12. Bratvold R.B., Bickel J.E., Lohne H.P., Value of information in the oil and gas industry, SPE Reservoir Evaluation & Engineering, 2009, V. 12(04), pp. 630–638,

DOI: https://doi.org/10.2118/110378-PA

13. Tax Code of the Russian Federation. Chapter 25.4 «Tax on Additional Income from Hydrocarbon Extraction» (Articles 333.43–333.56), Federal Law No. 199-FZ of July 19, 2018.

14. Brennan M.J., Schwartz E.S., Evaluating natural resource investments, Journal of Business, 1985, V. 58, No. 2, pp. 135–157, DOI: https://doi.org/10.1086/296288

15. Paddock J.L., Siegel D.R., Smith J.L., Option valuation of claims on real assets: The case of offshore petroleum leases, Quarterly Journal of Economics, 1988, V. 103, No. 3, pp. 479–508, DOI: https://doi.org/10.2307/1885541

The article presents the results of a study conducted using modern instrumental methods to examine changes in the properties of both newly formed and syngenetic minerals composing siltstone-sand terrigenous Devonian reservoirs. The study was performed in the eastern Volga-Kama anteclise, where the rocks were exposed to deep hydrothermal mineralized waters circulating through fractured zones. It was established that the resulting secondary minerals influence the reservoir properties of the productive formations. Among authigenic minerals, a positive effect was noted for microcrystalline quartz, which forms primarily on the faces of quartz grain fragments, as well as among the clay (pelitic) fraction of the rock. Syngenetic illite, which has a flaky morphology, typically impairs the filtration and capacity properties of silty-sandy rocks. However, when exposed to anoxic hydrothermal water containing iron and magnesium ions, it transforms into illite with acicular or ribbon-shaped crystals (epigenetic), characterized by higher porosity and permeability than the syngenetic type. The article also provides information on other epigenetically formed minerals. It is noted that a modified laboratory approach to studying epigenetic clays currently exists, enabling the accurate assessment of their quantity and type, which is necessary for constructing a correct petrophysical model and subsequent calculation of reservoir porosity, permeability, and oil saturation.

References

1. Garris M.A., On the epigenetic mineralization of the crystalline basement and the lower part of the sedimentary cover of Western Bashkiria (In Russ.), DAN SSSR, 1955, No. 2, pp. 329–331.

2. Timergazin K.R., On the genesis of sulfides in Devonian and older rocks in the east of the Russian platform (In Russ.), DAN SSSR, 1955, V. 105, No. 2, pp. 345–346.

3. Timergazin K.R., On hydrothermal sulfates in pre-Devonian and Devonian deposits in Western Bashkiria (In Russ.), DAN SSSR, 1955, V. 105, No. 3, pp. 562–563.

4. Florenskiy V.P., Lapinskaya T.A., Knyazev V.S., Gabbro-diabazy, diabazy i blizkie k nim porody vostochnoy chasti Russkoy platformy (Gabbro-diabases, diabases and related rocks of the eastern part of the Russian platform), Proceedings of the Moscow Oil Institute, 1955, V. 14, pp. 35–92.

5. Polyanin V.A., Rudopryavlenie v glubokikh nedrakh Tatarii (Mining in the deep bowels of Tatarstan), Kazan: Publ. of Museum of the TASSR, 1956, 12 p.

6. Timergazin K.R., Izbrannye trudy (Selected Works). Part 2: Dodevonskie obrazovaniya Zapadnoy Bashkirii i perspektivy ikh neftegazonosnosti (Pre-Devonian formations of Western Bashkiria and their oil and gas potential), Ufa: Gilem Publ., 2007, 448 p.

7. Khain V.E., Sokolov B.A., Flyuidodinamicheskiy analiz – novyy etap razvitiya ucheniya o neftegazonosnosti osadochnykh basseynov (Fluid dynamic analysis is a new stage in the development of the theory of oil and gas potential of sedimentary basins), In: Flyuidodinamichekiy faktor v tektonike i neftegazonosnosti osadochnykh basseynov (Fluid-dynamic factor in tectonics and oil and gas potential of sedimentary basins), Moscow: Nauka Publ., 1989, pp. 18–26.

8. Sitdikova L.M., Features of the fluid regime of the crystalline basement of the Tatar arch (In Russ.), Georesursy, 2007, No. 3(22), pp. 26–28.

9. Worden R.H., French M.W., Mariani E., Amorphous nanofilms result in growth of misoriented microcrystaline quartz cement maintaining porosity in deeply buried sandstones, Geology, 2012, V. 40(2), pp. 179–182, DOI: https://doi.org/10.1130/g32661.1

10. Masagutov R.Kh., Nikolaev A.A., Komilov D.U., Nigmatzyanova A.M., Connection between tectonic disturbances and oil content and epigenesis of Devonian terrigenous reservoirs in the east of the East European Platform (on the territory of the Republic of Bashkortostan) (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2024, No. 7, pp. 70–74, DOI: https://doi.org/10.24887/0028-2448-2024-7-70-74

11. Nigmatzyanova A.M., Masagutov R.Kh., Burikova T.V. et al., Integration of instrumental and field geophysical methods for studying terrigenous reservoir rocks of the Devonian Pashian horizon using the example of fields in the east of the Volga-Ural oil and gas province (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2025, No. 1, pp. 40–44, DOI: https://doi.org/10.24887/0028-2448-2025-1-40-44

12. Nigmatzyanova A.M., Gubaydullina A.A., Burikova T.V. et al., Reservoir classification based on petrophysical properties of Devonian siliciclastic sediments, Russian Platform, Republic of Bashkortostan (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2018, No. 4, pp. 22–25, DOI: https://doi.org/10.24887/0028-2448-2018-4-22-25

13. Sitdikov V.D., Nikolaev A.A., Kolbasenko E.A. et al., A new approach to the analysis of clay minerals in rocks by X-ray scattering (In Russ.), Neftegazovoe delo, 2021, V. 19, No. 5, pp. 75–83, DOI: https://doi.org/10.17122/ngdelo-2021-5-75-83

14. Izotov V.G., Sitdikova L.M., Perspektivy ispol’zovaniya nanotekhnologiy pri razrabotke mestorozhdeniy uglevodorodnogo syr’ya (Prospects for the use of nanotechnology in the development of hydrocarbon deposits), Collected papers “Povyshenie nefteotdachi na pozdney stadii razrabotki mestorozhdeniy i kompleksnoe osvoenie vysokovyazkikh neftey i bitumov” (Enhanced oil recovery at a late stage of field development and integrated development of high-viscosity oils and bitumens), Proceedings of International scientific and practical conference, Kazan’: Fen Publ., 2007, pp. 291–294.

15. Marakushev S.A., Belonogova O.V., An inorganic origin of the “oil-source” rocks carbon substance (In Russ.), Georesursy, 2021, No. 23(3), pp. 164–176,

DOI: https://doi.org/10.18599/grs.2021.3.19

Efficient drilling of complex carbonate reservoirs with a high degree of variability of properties is one of the key tasks of modern oil and gas geology. Successful drilling of horizontal wells directly depends on an accurate forecast of the distribution of zones with increased reservoir porosity and permeability properties. Geological models based on the interpolation of isolated borehole data often do not take into account the high vertical and lateral variability of a complex reservoir, which can lead to errors at the trajectory planning stage and significant economic risks: drilling suboptimal shafts with low effective penetration through the reservoir and reducing the efficiency of field development. The use of 3D seismic and derived attributes enables to qualitatively map the boundaries of seismic facies zones, while a model integrating seismic and borehole data is required for the quantitative prediction of parameters such as porosity. The use of the predictive porosity cube in the framework of performing seismogeological analysis (SGA) in the geological support of drilling horizontal wells is aimed at minimizing geological risks, increasing the opening length of an effective reservoir, and oil flow rates. Thus, the integrated use of SGA using a full range of geological and geophysical information in conditions of complex reservoirs becomes a necessary tool for improving the efficiency of drilling horizontal wells.

References

1. Urenko R.S., Vakhromeev A.G., Identification of Osinsky horizon organogenic structures by 2D and 3D seismic survey data in the north-eastern part of the Nepa-Botuoba anteclise (In Russ.), Nauki o Zemle i nedropol'zovanie, 2021, V. 44, No. 1, pp. 30–38, DOI: https://doi.org/10.21285/2686-9993-2021-44-1-30-38

2. Zadorozhnaya N.M., Tipizatsiya i klassifikatsiya rifogennykh formatsiy (Typification and classification of reef formations), Collected papers “Biota kak faktor geomorfologii i geokhimii. Rifogennye formatsii i rify v evolyutsii biosfery” (Biota as a factor in geomorphology and geochemistry. Reef formations and reefs in the evolution of the biosphere), Moscow: Publ. of Borissiak Paleontological Institute of the RAS, 2009, pp. 36–39.

3. Loucks R.G., Kerans Ch., Janson X., Introduction to carbonate environments, facies, and facies tracts, URL: https://www.beg.utexas.edu/lmod/_IOL-CM01/cm01-index.htm

4. Maksimova E.N., Chertina K.N., Tsiklicheskoe stroenie osinskogo gorizonta na primere odnogo iz mestorozhdeniy Nepsko-Botuobinskoy anteklizy (Cyclic structure of the Osinsky horizon using the example of one of the deposits of the Nepa-Botuoba anteclise), Collected papers “Litologiya osadochnykh kompleksov Evrazii i shel'fovykh oblastey” (Lithology of sedimentary complexes of Eurasia and shelf areas), Proceedings of IX All-Russian Lithological Conference (with international participation), Kazan, 30 September – 3 October 2019, Kazan': Publ. Of Kazan University, 2019, pp. 271–272.

5. Kizimov P.L., Kuznetsova L.S., Pivovar A.V., The experience of using seismic-geological analysis when drilling ring structures of the Osinskiy productive horizon

(In Russ.), Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdeniy, 2025, No. 5(401), pp. 37–42.

6. Priezzhev I.I., Shmar'yan L.E., Solokha E.V., A seismic inversion technique using a genetic algorithm with subsequent use of the inversion results in modeling the reservoir properties of the reservoir (In Russ.), Tekhnologii seysmorazvedki, 2009, No. 2, pp. 18–23.

7. Ampilov Yu.P., Safuanova K.R., Shteyn Ya.I., Prediction of thin-layer thickness using seismic full-waveform modeling (In Russ.), Vestnik MGU. Ser. 4. Geologiya = Moscow University Geology Bulletin, 2025, No. 2, pp. 106–112, DOI: https://doi.org/10.55959/MSU0579-9406-4-2025-64-2-106-112

This article presents the results of pilot testing of laser casing welding technology during well reconstruction using the sidetracking method at Samaraneftegaz JSC field. The main objective of this pilot project was to evaluate the applicability of laser welding of casing pipes in terms of its reliability and efficiency in the construction of high-tech wells, as well as in complex geological conditions, across the Rosneft Oil Company facilities. This laser casing welding technology was first applied at Rosneft Oil Company facilities and enables the replacement of threaded coupling connections in the casing with high-strength welds. The project envisages the use of a laser casing welding system, which creates high-torque, gas-tight welded joints. The candidate well for the pilot testing was selected based on the borehole geological conditions and design calculations of the casing's strength under operational loads, including the expected pressure during hydraulic fracturing. The pilot testing confirmed the reliability of the orbital laser casing welding system, including the use of an automatic ultrasonic testing system. It was also noted that additional time was spent on preparatory and final work to prepare the laser system for welding. The article provides a comparative analysis of the time required to assemble a casing pipe joint using welding and screwing. The high potential of laser casing welding technology for improving the efficiency and reliability of high-tech well construction is noted as the conclusion.

References

1. Sundeev S.Yu., Galiev R.R., Zagadov A.A. et al., Laser welding of casing pipes. Experience and application prospects (In Russ.), Neft'. Gaz. Novatsii, 2024, No. 10(287), pp. 13–16.

2. Fedoseev D.A., Korovin I.Yu., Koval' M.E. et al., On the possibility to reduce metal consumption for well structure (In Russ.), Neft'. Gaz. Novatsii, 2021, No. 8(249),

pp. 25–30.

3. Yakunin S.A., Agishev A.R., Nurgaleev A.R. et al., Well design with application of integral casing connections (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2024, No. 3, pp. 42–45, DOI: https://doi.org/10.24887/0028-2448-2024-3-42-45

4. Kompleks orbital'noy lazernoy svarki obsadnykh trub TongWELD (TongWELD orbital laser welding system for casing pipes), URL: https://ire-polus.com/wp-content/uploads/2024/05/ipg_ire_polus_tongweld_guide.pdf

The technology of scientific and methodological support for the construction of horizontal wells using geomechanical models has been implemented at PJSC «Surgutneftegas» since 2020 in order to select the optimal well design, safe drilling fluid density and drilling modes, based on well logging data of previously drilled wells, refined reservoir and hydraulic fracturing pressures, seismic profile, and core sample studies. Traditionally, the results of core studies, microscanners, the results of the extended leak test (XLOT-extended leak-off test) or the so-called stress tests (micro-fracturing), geological and technical monitoring data, sludge and cavernometry data are used as calibration data for building a geomechanical model. Based on theoretical studies and accumulated statistical materials it is proposed to include in the nomenclature of calibration information available data from geophysical surveys using the selective gamma defect thickness gauge, based on the interaction of gamma radiation with a material (rock, cement stone), which enables to interpret its characteristics (thickness, density, composition) and to evaluate the decompression zones. The use of the entire information obtained in the well design and construction cycle enables in the absence of actual values of the minimum horizontal stress, to calibrate the gradient of the well absorption onset, specifying the range of allowable density for trouble-free well construction. The article presents an implemented integrated approach to the construction of complex horizontal wells based on engineering analysis in the process of developing a drilling and completion strategy, an integral part of which is round-the-clock scientific and methodological support in real time.

References

1. Baklashov I.V., Kartoziya B.A., Mekhanicheskie protsessy v porodnykh massivakh (Mechanical processes in rock masses), Moscow: Nedra Publ., 1986, 270 p.

2. Dzhalatyan Ya.E., Filimonov A.Yu., Pertsev I.A. et al., Comprehensive integrated approach for reliable minimal horizontal stress profiling at reservoir conditions (In Russ.), Burenie i neft’, 2021, No. 9, pp. 16–22, DOI: https://doi.org/10.62994/2072-4799.2024.65.12.001

During field development, water cuts in well production are inevitable. This may be the result of ineffective reservoir pressure maintenance (RPM) systems, natural bottomwater coning, or geomechanical changes. A thorough understanding of the nature and causes of water cuts enables successful management of the RPM system, timely adjustments to the workover program and maintenance of oil production levels. One of the well-known analytical methods for determining the causes of water cut is the analysis of Chan plots. Combining this method with methods for determining well interaction coefficients enables to identify the areas of the interwellbore space that most significantly influence water cut dynamics. This article proposes a rapid method for determining the source of water cuts, including an analysis of the well interaction coefficient dynamics and time constants obtained by history matching the Capacitance-Resistance Model Injector-Producer Pair Based Representation (CRMIP). The variability of the CRMIP parameters and the relationship to the causes of water flooding were analyzed using synthetic data obtained using a hydrodynamic model. The applicability of an integrated approach to identifying the causes of well water cut is examined using field data from one of the Western Siberia fields. The retrospective analysis of the causes of increasing water cut in production wells was carried out. The author's method established the existence and direction of induced fracture (waterflooding fracture) development, which was confirmed by more advanced, resource-intensive methods such as hydrodynamic survey interpretation and multiwell deconvolution.

References

1. Ustyugov A.S., Sutyagin V.V., Galiullin M.M., Express-diagnostics of definition of wells water-flooding causes based on field data analysis (In Russ.), Avtomatizatsiya, telemekhanizatsiya i svyaz’ v neftyanoy promyshlennosti, 2016, No. 8, pp. 4–9.

2. Chan K.S., Water control diagnostic plots, SPE-30775-MS, 1995, DOI: https://doi.org/10.2118/30775-MS

3. Drofa P.M., Kolesnikova A.A., Murzakova A.F. et al., Improving the efficiency of field development using automated analytical methods to assess the wells interference and the nature of watering (In Russ.), PRONEFT’’. Professional’no o nefti, 2023, V. 8, No. 3, pp. 127–139, DOI: https://doi.org/10.51890/2587-7399-2023-8-3-127-139

4. Stepanov S.V., Sokolov S.V., Ruchkin A.A. et al., Considerations on mathematical modeling of producer-injector interference (In Russ.), Vestnik Tyumenskogo gosudarstvennogo universiteta. Fiziko-matematicheskoe modelirovanie. Neft’, gaz, energetika, 2018, V. 4, No. 3, pp. 146–164, DOI: https://doi.org/10.21684/2411-7978-2018-4-3-146-164

5. Yousef A.A., Gentil P.H., Jensen J.L., Lake L.W., A capacitance model to infer interwell connectivity from production and injection rate fluctuations, SPE-95322-PA, 2006, DOI: https://doi.org/10.2118/95322-PA

6. Sayarpour M., Development and application of capacitance-resistive models to water/CO2 floods: Doctor’s thesis, The University of Texas at Austin, 2008.

7. Stepanov S.V., Ruchkin A.A., Bekman A.D. et al., Review of original methods for reservoir simulation of oil and gas-oil fields based on CRM family models (In Russ.), PRONEFT’’. Professional’no o nefti, 2025, V. 10, No. 3, pp. 44–59, DOI: https://doi.org/10.51890/2587-7399-2025-10-3-44-59

8. Gubanova A.E., Khabibullin B.A., Orlov D.M., Koroteev D.A., Modified CR-type material balance model for well production forecasts in case of well treatments

(In Russ.), SPE-206511-MS, 2021, DOI: https://doi.org/10.2118/206511-MS

9. Shevtsov N.O., Stepanov S.V., Development of the material balance model for consideration of wells productivity index changes (In Russ.), Matematicheskoe modelirovanie, 2022, V. 34, No. 2, pp. 3–16, DOI: https://doi.org/10.20948/mm-2022-02-01

10. Bekman A.D., Accounting for stimulation treatments in modeling of oil reservoirs development using the material balance method (In Russ.), Matematicheskoe modelirovanie, 2022, V. 34, No. 6, pp. 22–36, DOI: https://doi.org/10.20948/mm-2022-06-02

For field development scenarios hydrodynamic models acquired particular relevance, as they most fully include the entire set of available geological and geophysical data from the reservoir. In a standard history matching process based on a single geological model, achieving a good fit may lead to extreme, non-geological values of petrophysical properties in the near-wellbore areas. Input data for modeling are often determined with significant uncertainty and cover only a small fraction of the reservoir; thus, the use of a single history-matched model fails to account for these inherent uncertainties. All of this can significantly reduce the predictive capabilities of such models and increase the risks in development decision-making, particularly for under-explored reservoirs or greenfields. Methods for assisted history matching of hydrodynamic models based on ensembles of geological models are considered in the article. This method enables to include existing uncertainties of the initial geological and petrophysical data, and obtain a set of hydrodynamic models matched to the actual production data during optimization. The advantages of this approach in automation of the process and reduction of possible errors (extreme values of properties). The methods were developed and tested on a real field, considered various optimization approaches and algorithms. Based on the results, the quality and compliance with the adaptation criteria assessed.

References

1. Bianco A., Cominelli A., Dovera L. et al., History matching and production forecast uncertainty by means of the ensemble kalman filter – A real field application,

SPE-107161-MS, 2007, DOI: https://doi.org/10.2118/107161-MS

2. Seiler A., Evensen G., Skjervheim J.-A. et al., Advanced reservoir management workflow using an EnKF based assisted history matching method, SPE-118906-MS, 2009, DOI: https://doi.org/10.2118/118906-MS

3. Peters E., Arts R.J., Brouwer G.K., Geel C.R., Results of the Brugge benchmark study for flooding optimization and history matching, SPE-119094-MS, 2009,

DOI: https://doi.org/10.2118/119094-MS

4. Evensen G., Data assimilation: The ensemble Kalman filter, Springer, 2007, 272 p., DOI: https://doi.org/10.1007/978-3-540-38301-7

5. Eremyan G.A., Vybor tselevoy funktsii dlya resheniya zadachi avtoadaptatsii geologo-gidrodinamicheskoy modeli (Selection of the objective function for solving the problem of automatic adaptation of a geological-hydrodynamic model): thesis of candidate of technical science, Tomsk, 2020.

6. Vremennyy reglament otsenki kachestv pat i priemki trekhmernykh tsifrovykh geologo-gidrodinamicheskikh modeley (Temporary regulations for assessing the quality of paths and accepting three-dimensional digital geological and hydrodynamic models), Moscow: Publ. of Rosnedra, 2012.

7. IRM. Rukovodstvo pol’zovatelya tNavigator. Adaptatsiya i Optimizatsiya (IRM. User’s Guide tNavigator. Adaptation and Optimization), 2024.

8. Cancelliere M., Verga F., Viberti D., Benefits and limitations of assisted history matching, SPE-146278-MS, 2011, DOI: https://doi.org/10.2118/146278-MS

A significant number of fields worldwide are complicated by the presence of massive gas caps in the absence of any clay barrier between the oil- and gas-saturated sections. One of the challenges related to well operation at the Russkoye oil and gas condensate field is gas breakthrough from the gas cap and within the gas lens zone. Nowadays to reduce the gas-oil ratio in production wells, technologies such as cycling well operation, backup packers, and waterflooding systems are being successfully implemented. A well completion technology using autonomous inflow control devices (AICDs) was also implemented. AICDs, by changing hydraulic properties, enable the inflow to be limited in those well intervals where a gas breakthrough occurs. The devices operate based on Bernoulli's principle: when oil, gas, or water passes through an AICD, a pressure differential occurs, which, in turn, depends on the viscosity of the fluid passing through. Therefore the real-life AICDs operation experience showed that these devices are highly effective in preventing gas breakthroughs. When replicating the technology to actually drilled wells without installed inflow control devices, the technology applicability limits should be considered and the number of devices per well should be correctly selected depending on the planned production rates.

References

1. Zernin A.A., Molokov R.A., Plitkina Yu.A. et al., Comprehensive monitoring of wells with inflow control devices at an oil and gas condensate field (In Russ.), Ekspozitsiya Neft’ Gaz, 2024, No. 9, pp. 86–91,

DOI: https://doi.org/10.24412/2076-6785-2024-9-86-91

2. Zyuzev E.S., Davydov A.A., Oparin I.A. et al., Autonomous inflow control devices usage experience (In Russ.), Ekspozitsiya Neft’ Gaz, 2023, No. 1, pp. 36–40, DOI: https://doi.org/10.24412/2076-6785-2023-1-36-40

3. Roslyakov K.S., Abdullin A.A., Muslimov B.Sh., Islamov R.R., Justification of the selection of the optimal size of inflow control devices for the development of oil and gas reservoirs (In Russ.), Ekspozitsiya Neft’ Gaz, 2024, No. 3, pp. 30–33, DOI: https://doi.org/10.24412/2076-6785-2024-3-34

4. Zyuzev E.S., Priz K.I., Davydov A.A. et al., Secondary completion technology with automated well control: a new stage in the development of sub-gas zones (In Russ.), Neftegaz.RU, 2025, No. 12, pp. 48–53.

5. Tkachenko E.I., Shirokov A.S., Grandov D.V. et al., Pilot area as a key to successful development of hard-to-recover reserves (In Russ.), Ekspozitsiya Neft’ Gaz, 2021, No. 1, pp. 19–22, DOI: https://doi.org/10.24412/2076-6785-2021-1-19-22

This paper analyzes experimental results obtained using the unique equipment of the Stim-Lab laboratory (USA) and published between 2004 and 2012. It is shown that at high values of phase filtration rates in proppant packs, equality of the average volumetric flow rates of the phases is achieved (at saturation values sufficiently different from one and zero). Also, based on the experimental data, the values of the dynamic pressure in the phases, the average intensity of shear stresses, the Weber number, and the capillary number were determined. It was shown that for gas-liquid flows, the moment of dispersion of one of the phases into small droplets is determined by the Weber number, since it is higher than the obtained capillary numbers, and its critical value is approximately in the range of 0,04-0,27. The analysis also showed that the ratio of the intensities of shear stresses in the phases is proportional to the ratio of the average volumetric velocities, and a model is proposed within which the thickness of the laminar boundary layer in the phases is assumed to be equal to explain the found ratio. Based on the obtained results, recommendation can be given that in the case of gas-liquid flow in a proppant pack and a Weber number value near the critical value, the fluid can be considered homogeneous with an effective viscosity value determined by the gas content value using standard models or correlations.

References

1. Bitao Lai, Miskimins J.L., A new technique for accurately measuring two-phase relative permeability under non-Darcy flow conditions, Journal of petroleum science and engineering, 2015, V. 127, pp. 398–408, DOI: https://doi.org/10.1016/j.petrol.2015.01.034

2. Nigmatulin R.I., Dinamika mnogofaznykh sred (The dynamics of multiphase media), Part 1, Moscow: Nauka Publ., 1987, 464 p.

3. Yihuai Zhang, Branko Bijeljic, Ying Gao et al., Quantification of nonlinear multiphase flow in porous media, Geophysical Research Letters, 2021, V. 48,

DOI: https://doi.org/10.1029/2020GL090477

4. Spurin C., Bultreys T., Bijeljic B. et al., Mechanisms controlling fluid breakup and reconnection during two-phase flow in porous media, Phys. Rev. E 100, 2019, V. 100, No. 4, DOI: https://doi.org/10.1103/PhysRevE.100.043115

5. Bitao Lai, Experimental measurements and numerical modelling of hight velocity multiphase non-darcy flow effects in porous media: PhD Thesis, 2010, Colorado School of mines.

6. Olson K.E., Haidar S., Milton-Tayler D., Olsen E., Multiphase non-Darcy pressure drop in hydraulic fracturing, SPE-90406-MS, 2004,

DOI: https://doi.org/10.2118/90406-MS

7. Volkov M.G., Bykov A.A., Tairova A.A. et al., Model of nonlinear single-phase filtration in a proppant pack at high Reynolds numbers (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2025, No. 7, pp. 94–98, DOI: https://doi.org/10.24887/0028-2448-2025-7-94-98

8. Leybenzon L.S., Dvizheniye prirodnykh zhidkostey i gazov v poristoy srede (Movement of natural liquids and gases in a porous medium), Moscow – Leningrad: Gostekhizdat Publ., 1947, 244 p.

Every year, the main reserves of oil fields are depleting, so the main task in the development of oil fields is the maximum extraction of oil reserves. One of the ways to intensify oil production is to combat salt deposition. Therefore it is more effective to prevent precipitation than to remove the consequences of salt deposition during the well operation. Consequently, the use of complexones-based inhibitor compositions is one of the main methods for protecting wells from salt deposition. Sulfates are the most difficult inorganic deposits to remove. In this work, the components for the salt deposition inhibitor were selected and their ability to prevent the precipitation of sulfates was studied. The dependence of the inhibitory capacity of the complexones on the addition of extra components was investigated. The optimal ratio of components in the mixture for inhibiting sulfate deposits was selected. The physical and chemical characteristics of the developed composition were determined, and the inhibitory composition was tested for its ability to reduce the corrosiveness of the environment. The developed salt deposition inhibitor was tested on several mineralized waters that contain various precipitating ions. Additionally, the adsorption and desorption properties of the inhibitory composition were investigated to determine its potential use in the technology of injecting inhibitors into the reservoir.

References

1. Silin M.A., Magadova L.A., Tolstykh L.I. et al., Promyslovaya khimiya (Industrial chemistry), Moscow: Publ. of Gubkin University, 2016, 350 p.

2. Kashchavtsev V.E., Mishchenko I.T., Soleobrazovanie pri dobyche nefti (Salt formation in oil production), Moscow: Orbita-M Publ., 2004, 432 p. 

3. Iolchuev A.M., Savenok O.V., Analysis of the method for controlling scale deposition by periodically injecting the scale inhibitor into the bottomhole formation zone

(In Russ.), Nauka. Tekhnika. Tekhnologii (Politekhnicheskiy vestnik), 2018, No. 4, pp. 53–71.

4. Shangaraeva L.A., Methods for preventing scale in oil wells (In Russ.), Innovatsii v nauke, 2013, No. 27, pp. 163–167.

5. Gaydamakina V.N., Gaydamakin V.N., Existing methods for preventing and combating salt deposits in submersible equipment (In Russ.), Nauchnyy zhurnal, 2018,

No. 7(30), pp. 28–30. – EDN: XWLPRJ

6. Voloshin A.I., Gusakov V.N., Fakhreeva A.V. et al., Scaling prevention inhibitors in oil production (In Russ.), Neftepromyslovoe delo, 2018, No. 11, pp. 60–72,

DOI: https://doi.org/10.30713/0207-2351-2018-11-60-72

7. Fink J.K., Petroleum engineer’s guide to oil field chemicals and fluids, Ch. 7. Scale Inhibitors, Waltham, USA: Gulf Professional Publishing, 2015, pp. 255–278,

DOI: https://doi.org/10.1016/B978-0-12-803734-8.00007-2

8. Fot K.S., Kolevatov A.N., Loshak A.A. et al., Effective technology for protecting production wells from scale deposits (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2025, No. 2, pp. 58-64, DOI: https://doi.org/10.24887/0028-2448-2025-2-58-64

9. Mandeev A.O., Gadel’shin I.R., The technology of scaling prevention (In Russ.), Aktual’nye problemy nefti i gaza, 2019, No. 2 (25), DOI: https://doi.org/10.29222/ipng.2078-5712.2019-25.art10

10. Glushchenko V.N., Silin M.A., Ptashko O.A. et al., Neftepromyslovaya khimiya. Oslozhneniya v sisteme plast-skvazhina-UPPN (Oilfield chemistry. Complications in the reservoir-well-oil treatment unit system), Moscow: MAKS press Publ., 2008, 328 p.

11. Valekzhanin I.V., Rafikov V.N., Sinitsyna T.I. et al., Testing a scale inhibitor squeeze technology into a bottomhole formation zone under the conditions of the Sorovskoye field (In Russ.), Ekspozitsiya Neft’ Gaz, 2023, No. 3, pp. 61–66, DOI: https://doi.org/10.24412/2076-6785-2023-3-61-66

12. Olajire A.A., A review of oilfield mineral scale deposits management technology for oil and gas production, Journal of Petroleum Science and Engineering, 2015, V. 135, pp. 723-737, DOI: https://doi.org/10.1016/j.petrol.2015.09.011

13. TTK «Rosneft Oil Company» No. P1-01.05 TTR-0148 “Primenenie khimicheskikh reagentov na ob»ektakh dobychi uglevodorodnogo syr’ya Kompanii” (Use of chemical reagents at hydrocarbon production facilities of the Company), version 1.00 M, 2023.

14. Aksenov D.A., Efficiency of preventing salt deposition using inhibitors (In Russ.), Ekonomika i sotsium, 2016, No. 5–3(24), pp. 64–66.

15. Shangaraeva L.A., Petukhov A.V., Research of the scale inhibitor’s adsorption-desorption properties in the down-hole equipment (In Russ.), Sovremennye problemy nauki i obrazovaniya, 2012, No. 6.

In the modern world, the demand for environmentally friendly energy sources is growing every day. Geothermal energy is an eco-friendly, renewable energy source not depending on weather conditions. Geothermal energy resources are highly varied and complex in nature and almost each of them has its own unique characteristics that must be taken into account for the effective use in heat recovery and electricity generation. When thermobaric conditions to which the fluid is subjected change along its entire path, the problem of the formation of poorly water-soluble deposits often arises, the most «problematic» of which are calcite, silica, iron oxides, and sulfates. The key factors influencing the formation of deposits are changes in temperature, pH, and liquid composition. The aim of this study is to select a base for a composition capable of dissolving deposits that predominantly consist of amorphous silica. The dissolving capacity of sodium carbonate Na2CO3, sodium hydroxide NaOH, and hydrofluoric acid HF was determined; deposit samples from the Mutnovskoye field (Kamchatka peninsula) were used as the soluble deposits. The solubility of the deposits was determined by the gravimetric method at various temperatures and solvent concentrations. The residual silicon concentration in the solution was determined by inductively coupled plasma optical emission spectroscopy (ICP-OES). The performed work shows the influence of temperature and solvent concentration on the quality of dissolution of amorphous silica deposits. The possibility of using various compositions as a base for treating geothermal wells from deposits is demonstrated.

References

1. Hassani K., Zheng W., A review of recent advances in mineral scaling in geothermal energy systems: mechanisms, mitigation, and case studies, Environmental Earth Sciences, 2025, V. 84, No. 14, DOI: https://doi.org/10.1007/s12665-025-12416-9

2. Garcia-Rios M., Jacquemet N., Geochemical modelling to evaluate mineral scaling risk in a geothermal loop, SPE-225485-MS, 2025,

DOI: https://doi.org/10.2118/225485-MS

3. Potapov V.V., Kashpura V.N., Alekseev V.I., A study of the growth of deposits in geothermal power systems (In Russ.), Teploenergetika = Thermal Engineering, 2001, No. 5, pp. 49–54.

4. Spinthaki A., Kamaratou M., Skordalou G. et al., A universal scale inhibitor: Adual inhibition/dispersion performance evaluation under difficult brine stresses, Geothermics, 2021, V. 89, DOI: https://doi.org/10.1016/j.geothermics.2020.101972

5. Paudyal S. et al., Silica and silicate scales formation in geothermal condition and their control, SPE-229152-MS, 2025, DOI: https://doi.org/10.2118/229152-MS

6. Kioka A., Nakagawa M., Theoretical and experimental perspectives in utilizing nanobubbles as inhibitors of corrosion and scale in geothermal power plant, Renew Sustain Energy Rev., 2021, V. 149, DOI: https://doi.org/10.1016/j.rser.2021.111373

7. Longval R. et al., An overview of silica scaling reduction technologies in the geothermal market, Energies, 2024, V. 17, No. 19, DOI: https://doi.org/10.3390/en17194825

8. Sarda J.P., Chemical leaching, Proceedings of 2nd NATA-CCMS Information Meeting on Hot Dry Rock Geothermal Energy, June 28-30, 1977, Los Alamos, New Mexico, USA, 1977.

9. Silin M.A., Magadova L.A., Kudryashov S.I. et al., The study of solubilizing ability of intensifying compositions in relation to calcium sulfate based on chelating agents (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2024, No. 11, pp. 108-113, DOI: https://doi.org/10.24887/0028-2448-2024-11-108-113

10. GOST 34781-2021. Drinkingwater. Prepared conditioned water for alcoholic beverages.Determination of the silicon concentration by the photometric method in the form of molybdosilicic acid.

11. Proost J., Santoro R., Jeriban S.A., Guiot I., Spectrophotometric determination of silicon in ultrapure, dilute hydrofluoric acid solutions, Microchemical Journal, 2008,

V. 89, No. 1, pp. 48–51, DOI: https://doi.org/10.1016/j.microc.2007.11.004

Ensuring the mechanical safety of buildings, especially in areas with permafrost soils, requires continuous geotechnical monitoring (GTM). A key problem in the lack of clear quantitative criteria for stabilizing monitored parameters and regulated procedures for justifying a reduction in monitoring frequency in current regulations. This leads to excessive costs and legal uncertainty when adjusting monitoring regimes. The article presents a methodology that establishes objective criteria for stabilization of soil temperature and deformations of foundations and basements of buildings. Based on GOST 25358‑2020 and GOST 24846‑2019, the criteria include three components: the accuracy criterion (changes between consecutive measurements do not exceed measurement error), the spatial randomness criterion (assumes a statistically random pattern of changes across nearby observation points and rules out systematic trends that might indicate ongoing geotechnical processes), the minimum sample criterion (at least three consecutive measurements or three annual cycles for natural characteristics). A detailed algorithm for adjusting GTM frequency is proposed, accounting for three scenarios regarding the presence and content of the monitoring program and differentiated legal procedures for each scenario in compliance with the Town Planning Code of the Russian Federation. The algorithm enables both reducing observation frequency when parameters stabilize and increasing it when dangerous deviations are detected (decaying deviations exceeding 80 % of permissible values, non‑decaying exceeding 50 %). Implementing the proposed approach will optimize monitoring costs while maintaining the required safety level through scientifically grounded regulation of observation frequency.

References

1. Zarya L.V., Pavlov V.A., Kanaev R.Yu. et al., Development of geotechnical monitoring of oil and gas fields construction facilities in the permafrost zone of Russia

(In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2022, no. 11, pp. 59–63, DOI: https://doi.org/10.24887/0028-2448-2022-11-59-63

2. Loktionov I.Yu., Zenkov E.V., D’yakova N.A. et al., Methodology for determining the scope of geotechnical monitoring work during the construction period (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2024, No. 11, pp. 56–59, DOI: https://doi.org/10.24887/0028-2448-2024-11-56-59

3. Piven’ A.V., Pogorzhal’skiy D.E., Matyukhin A.G. et al., Calculation method for determining the optimal class of leveling in the development of design solutions

(In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2023, No. 4, pp. 92–97, DOI: https://doi.org/10.24887/0028-2448-2023-4-92-97

4. Arnbrekht A.E., Vikulov G.E., Zenkov E.V. et al., Control of thawing of permafrost soils in the wellhead zone of production wells using geophysics methods (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2025, No. 8, pp. 84–88, DOI: https://doi.org/10.24887/0028-2448-2025-8-84-88

5. Filimonova V.K., Piven’ A.V., Sazhin A.F. et al., Identification of temperature anomalies during geotechnical monitoring (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2024, No. 4, pp. 117–120, DOI: https://doi.org/10.24887/0028-2448-2024-4-117-120

6. SP 22.13330.2016. Osnovaniya zdaniy i sooruzheniy (Foundations of buildings and structures).

7. SP 25.13330.2020. Osnovaniya i fundamenty na vechnomerzlykh gruntakh (Foundations and foundations on permafrost soils).

8. SP 497.1325800.2020. Osnovaniya i fundamenty zdaniy i sooruzheniy na mnogoletnemerzlykh gruntakh. Pravila ekspluatatsii (Foundations and foundations of buildings and structures on permafrost soils. Operating rules).

9. GOST 25358-2020. Soils. Field method of determining the temperature.

10. GOST 24846-2019. Soils. Measuring methods of strains of structures and building bases.

11. GOST 32019-2012. Technical condition monitoring of the unique buildings and constructions Rules of design and installation of permanent systems (stations) of monitoring.

12. Town-planning code of the Russian Federation of December 29, 2004 No. 190-FZ.

13. Letter of the Ministry of Construction and Housing and Communal Services of the Russian Federation No. 34072-DV/08 dated September 14, 2019. “O poryadke podtverzhdeniya sootvetstviya vnosimykh v proektnuyu dokumentatsiyu, poluchivshikh polozhitel’noe zaklyuchenie ekspertizy proektnoy dokumentatsii, izmeneniy trebovaniyam, ukazannym v ch. 3 st. 49 Gradostroitel’nogo Kodeksa RF” (On the procedure for confirming the conformity of changes made to design documentation that have received a positive conclusion from the design documentation review with the requirements specified in Part 3 of Article 49 of the Urban Development Code of the Russian Federation).

One of the typical challenges in the development of mature fields is the progressive water cut increase in the production, accompanied by a higher concentration of associated gases, particularly highly toxic and corrosion-active hydrogen sulfide H2S. The presence of dissolved H2S in marketable crude oil creates significant technological, economic, and environmental risks. Due to increasingly stringent quality standards and feedstock transportation requirements, the allowable H2S concentration in crude oil is regulated and must not exceed 20 ppm. Existing degassing methods are often energy-intensive, costly, or insufficiently effective in achieving the target specifications. This creates a need to upgrade the process equipment of oil treatment facilities and to develop new technical solutions. This paper considers a fundamentally new degassing unit for hydrogen-sulfide-containing crude oil based on shelf-type acoustic emitters, which promote the removal of sulfur-containing gas from the bulk oil phase through the action of physical cavitation fields. The main objective of the work was pilot-scale field testing of the developed cavitation-based oil treatment technology for the selective removal of hydrogen sulfide. The studies were carried out directly at an oil production facility of TatRITEKneft Territorial Production Enterprise. The tests confirmed the effectiveness of the technology under actual field operating conditions and demonstrated a high level of crude oil purification from hydrogen sulfide. The use of a physical treatment method, as opposed to chemical scavengers, reduces operating costs and improves the environmental safety of the process.

References

1. Sakhabutdinov R.Z., Shatalov A.N., Garifullin R.M. et al., Podgotovka i ochistka neftey ot serovodoroda (Preparation and purification of oils from hydrogen sulfide), Kazan: Ikhlas Publ., 2012, 162 p.

2. Mazgarov A.M., Kornetova O.M., Tekhnologii ochistki poputnogo neftyanogo gaza ot serovodoroda (Technologies for associated petroleum gas desulphurization) Kazan’: Publ. of KFU, 2015, 70 p.

3. Khuramshin R.T., Ismagilov F.R., Vishnevskaya E.E. et al., On the need to switch to a new type of sinks of hydrogen sulphide and mercaptans in oil, oil products, and gas (In Russ.), Mir nefteproduktov, 2018, No. 3, pp. 4–10.

4. Vetrova T.K., Morozov V.A., Dorogochinskaya V.A. et al., Effectiveness of various types of absorbers of hydrogen sulfide in residual fuel oil (In Russ.), Khimiya i tekhnologiya topliv i masel, 2011, No. 6, pp. 25–26.

5. Anufriev A.A., Sovershenstvovanie fizicheskikh metodov ochistki nefti ot serovodoroda (Improving physical methods for removing hydrogen sulfide from oil): thesis of candidate of technical science, Bugul’ma, 2023.

6. Shipilov D.D., Sovershenstvovanie tekhnologiy ochistki nefti ot serovodoroda na promyslovykh ob»ektakh (Improving technologies for oil purification from hydrogen sulfide at oilfield facilities): thesis of candidate of technical science, Bugul’ma, 2011.

7. Nikitin A.A., Karasev E.N., Dutlov E.V. et al., Selection of optimum technologyof decrease of hydrogen sulfidein petroleum residue (In Russ.), Neftepererabotka i neftekhimiya, 2014, No. 9, pp. 19–23.

8. Sakhabutdinov R.Z., Anufriev A.A., Shatalov A.N., Shipilov D.D., Improvement of hydrogen sulfide stripping physical methods (In Russ.), Ekspozitsiya Neft’ Gaz, 2017, no. 3, pp. 39–41.

9. Mullakaev M.S., Ul’trazvukovaya intensifikatsiya tekhnologicheskikh protsessov dobychi i pererabotki nefti, ochistki neftezagryaznennykh vod i gruntov (Ultrasonic intensification of technological processes of oil production and refining, purification of oil-contaminated waters and soils): thesis of candidate of technical science, Moscow, 2011.

10. Suleymanov M.A., Verbitskiy V.S., Evaluation of the application of the acoustic degassing method in oil production wells (In Russ.), Delovoy zhurnal Neftegaz.RU, 2024, No. 11(155), pp. 40–45.

11. Alfayaad A.G.Kh., Kemalov R.A., Kemalov A.F., Valiev D.Z., WaveWellTech: innovatsionnaya volnovaya tekhnologiya dlya intensifikatsii dobychi nefti (WaveWellTech: Innovative wave technology for enhanced oil production), Kazan’: Publ. of Kazan University, 2024, 123 p.

12. Alan-Reys N.V., Es’kin A.A., Zhilyakova T.S., Unru P.P., Effect of ultrasonic radiation on the air bubbles ascent time (In Russ.), Vestnik Inzhenernoy shkoly Dal’nevostochnogo federal’nogo universiteta, 2020, No. 2(43), pp. 116–123, DOI: https://doi.org/10.24866/2227-6858/2020-2-12

13. Tronov V.P., Separatsiya gaza i sokrashchenie poter’ nefti (Gas separation and reduction of oil losses), Kazan’: FEN Publ., 2002, 407 p.

14. Skoblo A. I., Molokanov Yu.K., Shchelkunov A.I., Protsessy i apparaty neftegazopererabotki i neftekhimii (Processes and equipment for oil and gas refining and petrochemistry), Moscow: Nedra Publ., 2000, 677 p.

15. Promtov M.A., Pul’satsionnye apparaty rotornogo tipa: teoriya i praktika: monografiya (Rotary-type pulsation devices: theory and practice: monograph), Moscow: Mashinostroenie-1 Publ., 2001, 260 p.

In the paper, the authors summarize the experience of studying the quality factors of girth welded joints in pipeline transport facilities for oil and oil products. Typical approaches to studying girth welded joints are described including the following: macro- and microstructure of welded joint cross-sections, a description of standard and special tests of laboratory samples taken from welds, hardness measurements in various zones of welded joints and metal along the crack edges, and fractographic analysis of crack surface is given. In addition, the authors of the paper reveal the subtle aspects of the studies: the use of various non-destructive testing methods at the first stage of the studies to identify the defectiveness of girth welded joints and its compliance with the requirements of industry regulatory documentation, the use of local chemical analysis methods for monitoring the phases composition in welds, and comparison of results obtained by different methods. Among the most frequently encountered factors are the following: manufacturing defects of welded joints (lack of penetration, incomplete fusion, slag lines, pores); associated earthworks with deviations from the standard operating procedures of their execution and generation of excessive bending stresses in adjacent girth welded joints; installation of repair structures that generate additional bending stresses in adjacent girth welded joints.

References

1. Skorodumov S.V., Salikhov R.N., Investigating the quality of weld affecting the reliability of operation of main oil pipeline structures (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2024, No. 7, pp. 130–135, DOI: https://doi.org/10.24887/0028-2448-2024-7-130-135

2. Skorodumov S.V., Ivanushkin D.G., Non-destructive inspection methods in fracture diagnostics of pipelines (In Russ.), Nauka i tehnologii truboprovodnogo transporta nefti i nefteproduktov = Science&Technologies: Oil and Oil Products Pipeline Transportation, 2025, V. 15, No. 6, pp. 499–509, DOI: https://doi.org/10.28999/2541-9595-2025-15-6-499-509

3. Makhutov N.A., Neganov D.A., Studenov E.P., Skorodumov S.V., Analysis of process of deformation and fracture of oil pipeline under single static loading (In Russ.), Nauka i tehnologii truboprovodnogo transporta nefti i nefteproduktov = Science&Technologies: Oil and Oil Products Pipeline Transportation, 2023, V. 13, No. 5,

pp. 395–401.

4. Skorodumov S.V., Salikhov R.N., Features of fractographic studies at pipeline transport facility reliability factors research (In Russ.), Problemy sbora, podgotovki i transporta nefti i nefteproduktov, 2025, No. 6(158), pp. 133–148, DOI: https://doi.org/10.17122/ntj-oil-2025-6-133-148

In the context of the global energy transition and stricter climate regulation, accurately assessment of the carbon footprint of oil refineries is becoming not just a reporting element but a strategic necessity, directly impacting the competitiveness of their products. Oil refineries produce a wide range of petroleum products, and it's essential to find a fair way to allocate the refinery's total emissions among individual product types. This article examines key methodological approaches to determining greenhouse gas emissions at refineries, from greenhouse gas emissions inventories to comprehensive life cycle assessments of petroleum products. Existing methods for allocating products by mass, energy content, economic value, and added value, their advantages, methodological limitations, and applicability depending on the assessment objectives are analyzed. The conclusion is that the energy content allocation method is preferable in terms of physical validity, data comparability, and compliance with international requirements, including CORSIA standards. The results of this work provide a methodological basis for reliably assessing the carbon intensity of petroleum products, serve as a foundation for making management decisions regarding the company's low-carbon development, enable an assessment of the carbon footprint of one of Rosneft's Oil Company refined petroleum products, and enable the company to offer end consumers products with a proven low carbon footprint.

References

1. GOST R ISO 14067-2021. Greenhouse gases. Carbon footprint of products. Requirements and guidelines for quantification.

2. GOST R ISO 14044-2019. Environmental management. Life cycle assessment. Principles and framework.

3. Federal Law No. 296-FZ of July 2, 2021 “Ob ogranichenii vybrosov parnikovykh gazov” (On Limiting Greenhouse Gas Emissions),

URL: http://www.kremlin.ru/acts/bank/47013

4. Morettia S., Moroa A., Edwardsa R. et al., Analysis of standard and innovative methods for allocating upstream and refinery GHG emissions to oil products: A review, Applied Energy, 2017, V. 206, pp. 372–381, DOI: https://doi.org/10.1016/j.apenergy.2017.08.183

5. Abramov V.I., Vlasov A.V., Perfil’ev D.O., Carbon footprint: Assessment techniques, comparison of methodologies and calculation prospects in Russia (In Russ.), Kreativnaya ekonomika, 2024, V. 18, No. 8, pp. 2101–2124, DOI: https://doi.org/10.18334/ce.18.8.121475