Probabilistic Assessment of Resources and Reserves in Oil and Gas Exploration

The problem of forecasting the results of geological exploration at various stages is very relevant in the development of licensed areas. According to the authors, it can be solved through the technology of probabilistic assessment of localized resources and reserves, taking into account the probabilities of the field existence. The purpose of the study is to increase the reliability of such estimates based on a geostatistical approach to interpreting data from modern methods of geological investigation. To achieve this goal, two scientific tasks were solved: the task of estimating the probability of the existence of a field (Pg) at the evaluation stage, and the task of estimating the probability of the existence of a field at the point of the exploration well (Pe) at the exploration stage. The article uses model data to show that the key components of Pg – the probabilities of the existence of a reservoir and a seal within the trap – can be estimated based on the results of their seismic prediction: final maps and maps of the standard deviation of the discrepancies. The probability of the existence of structural traps can be obtained from stochastic modeling of structural surfaces, and the probability of their filling – from basin modeling. The Pe components – the probability of a reservoir existence at the point of the exploration well and the probability of a reservoir top to be above the product-water contact also can be obtained from the results of seismic forecasting. The main advantage of the proposed approach is an objective quantitative assessment of the probability of the field’s existence, based on modern research technologies and the degree of study of objects. The main problem is the degree of reliability of the estimation of statistical parameters of the general population according to the sample data. Although the first results of its solution look encouraging, research in this direction needs to be continued.

1. Abdrazakova D.I., Lebedev M.V., Ermakov P.V., Khazipov R.L., Zakrevsky K.E. (2025). Structural uncertainties assessment of the geological model based on operational drilling data (on the example of the VK reservoir of the Kamennoe license area). Neftyanoe khozyaystvo = Oil industry, 1, pp. 6–11. (In Russ.) https://doi.org/10.24887/0028-2448-2025-1-6-11

2. Aronov V.I., Poroskun V.I. (2002). On the issue of constructing maps of interpolation errors. Geofizika, 2, pp. 39–40. (In Russ.)

3. Burstein L.M., Grekova L.S., Zhilina I.V. (2006). Forecast of oil and gas potential based on the analysis of conditional probabilities (using the example of the Upper Jurassic oil and gas complex in the south-east of Western Siberia). Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdeniy = Geology, geophysics and development of oil and gas fields, 5–6, pp. 85–91. (In Russ.)

4. Chiles J.-P., Delfiner P. (1999). Geostatistics: modeling spatial uncertainly. New York: John Wiley & Sons, 696 p. https://doi.org/10.1002/9780470316993

5. Demyanov V.V., Savelyeva E.A. (2010). Geostatistics: theory and practice. Moscow: Nauka, 327 p. (In Russ.)

6. Dubrule Olivier (2003). Geostatistics for Seismic Data Integration in Earth Models. Zeist: EAGE, 296 p. https://doi.org/10.1190/1.9781560801962

7. Emelyanova N.M., Poroskun V.I. Probabilistic oil and gas resource assessment for subsurface areas taking into account the dependence of geological risks of aggregated local objects by area and section. Neftegazovaya Geologiya. Teoriya I Praktika, 16(3). (In Russ.) https://doi.org/10.17353/2070-5379/28_2021

8. Fokin A.N. (2011). Risks and uncertainties in the exploration process. ROGTEC, 27, pp. 76–84. (In Russ.)

9. Fotiadi E.E., Demin V.I., Leontovich V.B., Rastegin A.A., Kontorovich A.E. (1981). Forecast of oil and gas fields. Moscow: Nedra, 350 p. (In Russ.)

10. Galkin V.I., Galkin S.V., Levinzon I.L., Ponomarev V.A. (1997). Forecasting of oil and gas potential of local structures by probabilistic and statistical methods. Izvestiya VUZov. Neft’ i gaz, 1, pp. 31–35. (In Russ.)

11. Galkin S.V. (2009). Probabilistic forecast of geological risks in the search for oil and gas deposits. Perm: Knizhny mir, 223 p. (In Russ.)

12. Galkin S.V. (2012). Methodology of accounting for geological risks at the stage of prospecting and exploration of oil fields. Vestnik PNIPU. Geologiya. Neftegazovoe i gornoe delo, 4, pp. 23–32. (In Russ.) https://doi.org/10.15593/2224-9923/2012.4.3

13. Glukhov T.V. (2022). A new approach to risk assessment and volumetric parameters uncertainty analysis for exploration process. Ekspozitsiya Neft’ Gaz, 6, pp. 34–38. (In Russ). DOI: 10.24412/2076-6785-2022-6-34-38.

14. Glukhov T.V., Lebedev M.V. (2025). Assessing the probability of a gas accumulation in the Upper Cretaceous NB1 reservoir unit in the Nadym-PurTaz area. Neftegazovaya Geologiya. Teoriya I Praktika, 20(4). (In Russ). https://www.ngtp.ru/rub/2025/38_2025

15. Grekova L.S. (2011). Prognosis of probable oil and gas potential of local structural traps (with reference to horizon YU1 of south-east of West Siberia, Tomsk region). Russian oil and gas geology, 5, pp. 84–91 (In Russ.)

16. Ikon K., Olyunina O. (2019). Methodological approach for assesing the risks of exploration drilling and the experience forecasting of numbers of discoveries as a result of implimentation explorational program (as in the case of north-eastern areas of Western Siberia). Trophimukovckie chteniya-2019, pp. 170–173. (In Russ.)

17. Kontorovich A.E., Eder L.V. (2015). A new paradigm of the development strategy for the mineral resource base of the oil producing industry in the Russian Federation. Mineral’nye resursy Rossii. Ekonomika i upravlenie, 5, pp. 8–17. (In Russ.)

18. Novokreschin A.V. (2008). Algorithms of structural constructions based on a statistical model based on borehole and seismic data: abstract of the dissertation for PhD of Engineering Sciences: 25.00.10. Novosibirsk, 21 p. (In Russ.)

19. Orlova L.A., Kuranov A.V., Otmas A.A., Zeger N.А. (2010). Analysis of the reliability of resource estimates of local objects before exploration. Neftegazovaya geologiya. Teoriya i praktika = Petroleum geology. Theoretical and applied studies, 5(4), pp. 1–12. (In Russ.)

20. Otmas A.A. (2006). On the issue of the reliability of estimates and geological risks during exploration (using the example of the Kaliningrad region). Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdeniy = Geology, geophysics and development of oil and gas fields, 8, pp. 35–40. (In Russ.)

21. Otmas A.A.S., Podol’skiy Yu.V. (2014). Evaluation of development-well success ratio and approving factor of local structures’ resources in Nenets autonomous district. Neftegazovaya geologiya. Teoriya i praktika = Petroleum geology. Theoretical and applied studies, 9(1), pp. 1–13. (In Russ.) https://doi.org/10.17353/2070-5379/8_2014

22. Polishchuk A.V. (2020). Exploration history analysis and adjustment of geological risk assessment template. Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdeniy = Geology, geophysics and development of oil and gas fields, 2, pp. 19–30. (In Russ.) https://doi.org/10.30713/2413-5011-2020-2(338)-19-30

23. Polishchuk A.V. (2022). Analysis of hydrocarbon systems and assessment of oil and gas potential in the Jurua basin of the Solimoins Basin (Brazil): dissertation for PhD of Geologo-Mineralogical Sciences: 1.6.11. Tyumen, 189 p. (In Russ.)

24. Polyakov A.A. (2016). Systematic approach to the risk reduction analysis during prospecting and exploration activity of oil and gas fields. Neftegazovaya geologiya. Teoriya i praktika = Petroleum geology. Theoretical and applied studies, 11(1), pp. 1–22. (In Russ.) https://doi.org/10.17353/2070-5379/3_2016

25. Polyakov A.A., Murzin Sh.M. (2012). International experience in geological risk analysis. Neftegazovaya geologiya. Teoriya i praktika = Petroleum geology. Theoretical and applied studies, 7(4), pp. 1–29. (In Russ.)

26. Shatrov S.V. (2018). Estimation of hydrocarbon resources based on joint modeling of probabilistic and volumetric characteristics of search facilities: dissertation for PhD of Geologo-Mineralogical Sciences: 25.00.12. Ufa, 160 p. (In Russ.)

27. Sysoev A. P., Novokreschin A.V. (2001). Statistical interpretation models based on the integrity of seismic and borehole data. Geofizika, 1, pp. 31–41. (In Russ.)

28. Yanevits E.A., Lapkovsky V.V., Lebedev M.V. (2022). Stochastic modeling of structural uncertainties as a basis for probabilistic estimation of hydrocarbon resources. Proc. Conf: Ways to realize the oil and gas potential of Western Siberia. Khanty-Mansiysk, pp. 154–164. (In Russ.)