Carbonate reservoirs are characterized by low production rates and low oil recovery factors. This may be due to imperfection of the conventional waterflooding system. To overcome the production challenges, we need to improve our knowledge of waterflooding mechanisms in dual porosity carbonate reservoirs. Dedicated flow-after-flow tests involved 36 injection wells in carbonate reservoirs of Ttaneft PJSC. On the resulting Inflow Performance Relationships (IPR) curves intersection points represent limited pressures. Any pressure increase above these values would result in a rapid water breakthrough. The limited pressure values were also determined from sharp increase of the permeability-thickness product evident from the interpretation of injection and fall-off curves at different liquid rates made possible through different-size chokes. Predictably, this is caused by closing of fractures and matrix at pressure drawdown; maximum permeability was recorded on the injection curve with maximum injectivity. The resultant bar graphs of limited bottomhole pressure, wellhead pressure, and differential pressure vary significantly and lack normal distribution. So, further attempt was made to obtain a relationship between a limited pressure and some influencing parameter. The reservoir pressure was found to be the influencing parameter. The obtained relationships are characterized by high correlation number (R2>0.88) and have a physical meaning. The paper offers equations to determine a limited bottomhole pressure as a function of reservoir pressure for different types of carbonate reservoirs with a calculation error of less than 10 %. Maintenance of limited pressures will allow to improve the performance of waterflooded development of carbonate reservoirs.
References
1. Bakirov A.I., Sovershenstvovanie tekhnologii izvlecheniya nefti zavodneniem iz karbonatnykh kollektorov mestorozhdeniy Tatarstana (Improving the technology of oil recovery by waterflooding from carbonate reservoirs of Tatarstan fields): thesis of candidate of technical science, Bugul'ma, 2018.
2. Nugaybekov R.A., Shafigullin R.I., Kaptelinin O.V. et al., Evaluation of flooding system performance on oil deposits in carbonate reservoirs of Novo-Yelkhovskoe oil field (In Russ.), Problemy sbora, podgotovki i transporta nefti i nefteproduktov, 2011, no. 3, pp. 94-97.
3. Mukanov A.R., Bigeldiyev A., Batu A., Kuvanyshev A.M., Features of field development with tight carbonate reservoirs by waterflooding, SPE-202534-MS, 2020, DOI: https://doi.org/10.2118/202534-MS
4. Ligin'kova Ya.S., Issledovanie osobennostey zavodneniya zalezhey nefti v karbonatnykh kollektorakh (na primere Gagarinskogo i Opalikhinskogo mestorozhdeniy) (Investigation of the features of waterflooding of oil deposits in carbonate reservoirs (on the example of the Gagarinskoye and Opalikhinskoye fields)), Collected papres “Problemy razrabotki mestorozhdeniy uglevodorodnykh i rudnykh poleznykh iskopaemykh” (Problems of development of deposits of hydrocarbon and ore minerals), Proceedings of XII All-Russian scientific and technical conference, Perm: Publ. of PSTU, 2019, pp. 43–45.
5. Molokovich Yu.M., Markov A.I., Suleymanov E.I. et al., Vyrabotka treshchinovato-poristogo kollektora nestatsionarnym drenirovaniem (Development of a fractured-porous reservoir by non-stationary drainage), Kazan': Regent" Publ., 2000, 156 p.
6. Diyashev R.N., Sovmestnaya razrabotka neftyanykh plastov (Joint development of oil reservoirs), Moscow: Nedra Publ., 1984, 208 p.
7. RD 153-39.0-918-15. Metodicheskoe rukovodstvo po opredeleniyu predel'no-dopustimykh zaboynykh davleniy (Methodological guidelines for determining the maximum permissible bottomhole pressures), Bugul'ma: Publ. of TatNIPIneft', 2015, 29 p.
8. Iktisanov V.A., Bobb I.F., Ganiev B.G., Study of the problem of optimization of bottomhole pressure for fractured-porous reservoirs (In Russ.), Neftyanoe khozyaystvo = Oil Industry, Neftyanoe khozyaystvo, 2017, no. 10, pp. 94–97, DOI: 10.24887/0028-2448-2017-10-94-97
9. Iktisanov V.A., Bobb I.F., Fokeeva L.Kh., Consequences of deviations of bottomhole pressures from optimal values (In Russ.), Oil Gas Journal Russia, 2017, no. 8(118), pp. 60–64.
