On gas-oil ratio forecasting for Western Siberia oil fields

There is an increase in associated petroleum gas (APG) production above design values at a number of oil fields in the final stage of development. The reason is the high water cut of productive formations and the release of free gas from oil in the bottom–hole zone when the bottom-hole pressure decreases below the saturation pressure. Exceeding the planned production of APG leads to malfunction of processing plants, complications in the processing of wellbore fluids and the need to burn excess gas on flares. A brief review of studies of the genesis of gases dissolved in reservoir water is performed, modern methods for predicting the gas content in mineralized water are considered. Existing software systems have low convergence of calculated values with laboratory and field data at high values of water cut and the gas-oil ratio (GOR). In order to increase accuracy, the Cubic Plus Association (CPA) type equation of state was modified. Empirical correlations were developed that estimate the percentage of water molecules forming hydrogen bonds in wells and field collection systems. The modified equation was tested at the fields of Rosneft Oil Company. A comparison of the measured GOR values with the design and calculated according to CPA showed that with a water cut of more than 92 % and a bottom–hole pressure below saturation pressure, the smallest error (5,47–10,8 %) is between the actual and calculated GOR according to CPA; in other cases, between the measured and the design GOR.

References

1. Khalfin R.S., Zeygman Yu.V., Predicting associated petroleum gas production taking into account the dissolution of gas in formation water based on the adaptation of the cubic equation of state (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2021, No. 9, pp. 65–69, DOI: https://doi.org/10.24887/0028-2448-2021-9-65-69

2. Mikhaylov V.G., Ponomarev A.I., Topol’nikov A.S., Prediction of gas factor taking into account gas dissolved in the water at late stages development of oil fields

(In Russ.), SOCAR Proceedings, 2017, No. 3, pp. 41–48, DOI: https://doi.org/10.5510/OGP20170300322

3. Kordik K.E., Bortnikov A.E., Leont’ev S.A., Results of laboratory modeling of formation fluid interaction with the injected water in conditions simulating liquid intensive discharge out of a formation (In Russ.), Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdeniy, 2015, No. 2, pp. 66–69.

4. Batalin O.Yu., Vafina N.G., Transformation of deep fluid flow in the process of oil and gas field formation of north Western Siberia (In Russ.), Georesursy, 2019,

No. 21(3), pp. 25–30, DOI: https://doi.org/10.18599/grs.2019.3.25-30

5. Akulinchev B.P., Rakhbari N.Yu., The mechanism of water dissolved and free gases interaction during forming of hydrocarbons deposits (In Russ.), Georesursy. Geoenergetika. Geopolitika, 2011, No. 2(4).

6. Novikov D.A., Borisov E.V., Geochemistry of water-soluble gases in the oil and gas bearing sediments of the zone of junction between the Yenisei-Khatanga and the West Siberian basins (the Arctic regions of Siberia) (In Russ.), Georesursy, 2021, V. 23, No. 4, pp. 2–11, DOI: https://doi.org/10.18599/grs.2021.4.1

7. Novikov D.A., Gordeeva A.O., Chernykh A.V. et al., The influence of trap magmatism on the geochemical composition of brines of petroliferous deposits in the western areas of the Kureika Syneclise (Siberian Platform) (In Russ.), Geologiya i geofizika = Russian Geology and Geophysics, 2021, V. 62, No. 6, pp. 861–881,

DOI: https://doi.org/10.15372/GiG2020160

8. Kutyrev E.F., Shkandratov V.V., Belousov Yu.V., Some results of physical modeling of gas exchange processes in an oil-injected water system (In Russ.), Georesursy, 2008, No. 5, pp. 33–36.

9. Kanzafarov F.Ya., Change of properties of oil gas while in Samotlorskoye oilfield development (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2009, No. 1,

pp. 47–49.

10. Bortnikov A.E., Kutyrev E.F., Belousov Yu.V. et al., On the change in the gas factor of oil during the development of flooded deposits (In Russ.), Territoriya Neftegaz, 2010, No. 2, pp. 62–65.

11. Sorokin A.V., Sorokin V.D., Sorokina M.R., Formation of oil zones with different physical and chemical properties during the development of a deposit (In Russ.), Izvestiya vuzov. Neft’ i gaz, 2011, No. 3(87), pp. 41–47.

12. McGee K.A., Susak N.J., Sutton A.J., Haas J.L., The solubility of methane in sodium chloride brines, U.S. Geological Survey Open-File Report 81-1294, 1981, 42 p.,

DOI: https://doi.org/10.3133/ofr811294

13. Gang Gao, Zhilong Huang, Baojia Huang et al., The solution and exsolution characteristics of natural gas components in water at high temperature and pressure and their geological meaning, Petroleum Science, 2012, V. 9, pp. 25–30, DOI: https://doi.org/10.1007/s12182-012-0178-9

14. Li Sun, Jierong Liang, Solubility calculations of methane and ethane in aqueous electrolyte solutions, Journal of Solution Chemistry, 2021, No. 50(6), pp. 920–940.

15. Sørensen H., Pedersen K.S., Christensen P.L., Modeling of gas solubility in brine, Organic Geochemistry, 2002, No. 33, pp. 635–642.

16. Novak N., Kontogeorgis G.M., Castier M., Economou I.G., Modeling of gas solubility in aqueous electrolyte solutions with the eSAFT-VR Mie equation of state, Industrial and Engineering Chemistry Research, 2021, No. 60(42), pp. 15327–15342.

17. Baojiang Sun, Haikang He, Xiaohui Sun et al., Prediction method of solubility of carbon dioxide and methane during gas invasion in deep-water drilling, Journal of Contaminant Hydrology, 2022, V. 251, DOI: https://doi.org/10.1016/j.jconhyd.2022.104081

18. Taherdangkoo R., Liu Q., Xing Y. et al., Predicting methane solubility in water and seawater by machine learning algorithms: Application to methane transport modeling, Journal of Contaminant Hydrology, 2021, V. 242, DOI: https://doi.org/10.1016/j.jconhyd.2021.103844

19. R. Nakhaei-Kohani, Atashrouz S., Hadavimoghaddam F. et al., Solubility of gaseous hydrocarbons in ionic liquids using equations of state and machine learning approaches, Scientific Reports, 2022, No. 12(1), DOI: https://doi.org/10.1038/s41598-022-17983-6

20. Kontogeorgis G.M., Voutsas E.C., Yakoumis I.V., Tassios D.P., An equation of state for associating fluids, Industrial and Engineering Chemistry Research, 1996,

No. 35, pp. 4310–4318, URL: https://www.sci-hub.ru/10.1021/ie9600203

21. Debye P., Huckel E., On the theory of electrolytes, Physikalische Zeitschrift, 1923, No. 24, pp. 185–206.

22. Kontogeorgis G.M., Michelsen M.L., Folas G.K. et al., Ten years with the CPA (Cubic-Plus-Association) equation of state. Part 1. Pure compounds and self-association systems, Industrial and Engineering Chemistry Research, 2006, No. 45, pp. 4855–4868.

23. Aasberg-Petersen K., Stenby E., Fredenslund A., Prediction of high-pressure gas solubilities in aqueous mixtures of electrolytes, Industrial and Engineering Chemistry Research, 1991, No. 30, pp. 2180–2185, DOI: https://doi.org/10.1021/ie00057a019

24. Lewis G.N., Randall M.J., The activity coefficient of strong electrolytes, Journal of the American Chemical Society, 1921, No. 43, pp. 1112–1153.