Foreign projects for Rosneft Oil Company are one of the key areas for the hydrocarbon resource base development. Currently, Rosneft is running projects in Myanmar, Egypt, Iraq, Cuba and offshore of Mozambique. One of the special projects is the Varadero field on the territory of the Republic of Cuba. The oil bearing capacity at the field is found in the Upper Jurassic and Lower Cretaceous carbonate formations. The Varadero oil is a typical representative of the naphthenic oils of the North Cuban Oil Basin by its physico-chemical properties. It is characterized by high viscosity and density, significant content of resin-asphaltene compounds and sulfur. One of the essential activities during oil production at the Varadero field is the well stimulation and mitigation response in well operation. In relation to the object under consideration, it is possible to distinguish the fight against the formation of high-viscosity oil-water emulsions, the deposition of high molecular weight components and oilfield equipment corrosion. To restore the wells productivity and keep oil production at required level, it is recommended to use complex acid treatment technologies with use of organic solvents.
The article provides an algorithm for designing complex acid treatment technologies for the conditions of the Varadero field, based on a series of laboratory studies on the selection of acid compositions and solvents for cleaning the critical matrix from asphaltene deposits. The results of acid treatments are presented and an analysis of their effectiveness is performed.
References
1. Ananev V.V., Verzhbitskiy V.E., Obukhov A.N. et al., Geology and petroleum potential of the Gulf of Mexico, Cuba, SPE-171212-MS, 2014, DOI: https://doi.org/10.2118/171212-MS
2. Smith G.E., Hurlburt G., Li V.P., Heavy oil carbonate: Primary production in Cuba, SPE-79002-MS, 2002, DOI: https://doi.org/10.2118/79002-MS
3. Androulidakis Y., Kourafalou V., Hole L.R. et al., Pathways of oil spills from potential cuban offshore exploration: Influence of ocean circulation, J. Mar. Sci. Eng., 2020, V. 8, pp. 535, DOI: https://doi.org/10.3390/jmse8070535
4. Schenk C.J., Jurassic-Cretaceous composite total petroleum system and geologic models for oil and gas assessment of the North Cuba Basin, Cuba, In: U.S. Geological Survey North Cuba Basin Assessment Team, Jurassic-Cretaceous Composite Total Petroleum System and geologic assessment of oil and gas resources of the North Cuba Basin, Cuba, U.S. Geological Survey Digital Data Series DDS–69–M. Chap. 2, 94 p., URL: https://www.arlis.org/docs/vol1/A/289003955/289003955b.pdf
5. Gonsales P.E.O, Ramires A.B., Drilling strings design for construction of extended reach wells (on the example of Cuba), Neftegazovoe delo, 2019, V. 17, no. 5, pp. 15-22, DOI: http://dx.doi.org/10.17122/ngdelo-2019-5-15-22
6. Gusakov V.N., Kashtanova L.E., Nazarova S.V. et al., Design of technologies for processing bottom-hole zone of Varadero oilfield (Cuba) (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2017, no. 12, pp. 126–130, DOI: https://doi.org/10.24887/0028-2448-2017-12-126-130
7. Yakubova S.G., Manaure D.A., Machado R.A. et al., Effect of oxyethylated isononylphenol (neonol) on viscosity characteristics of water–oil emulsions , Petroleum Science and Technology, 2018, V. 36, no. 17, pp. 1389–1395, DOI: https://doi.org/10.1080/10916466.2018.1482318
8. Voloshin A.I., Dokichev V.A., Fakhreeva A.V. et al., Composition and physico-chemical properties of high-viscosity oil of Varadero oil field (Cuba) (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2019, no. 9, pp. 34-37, DOI: https://doi.org/10.24887/0028-2448-2019-9-34-37
9. Manaure D.A., Fakhreeva A.V., Voloshin A.I. et al., Oil composition of Varadero (Cuba) deposits according to IR and NMR spectroscopy (In Russ.), Bashkirskiy khimicheskiy zhurnal, 2019, V. 26, no. 2, pp. 55-60.
10. Guzmán R., Ancheyta J., Trejo F., Rodríguez S., Methods for determining asphaltene stability in crude oils, Fuel, 2017, V. 188, pp. 530–543, DOI: https://doi.org/10.1016/j.fuel.2016.10.012
11. API 42. Recommended practices for laboratory evaluation of surface active agents for well stimulation, Washington D.S.: American Petroleum Institute. 2nd Edition, 1990, 22 p.
12. Shaydullin V.A., Vakhrushev S.A., Magzumov N.R. et al., Features of killing wells operating fractured formations with abnormally low formation pressures and high gas factor (In Russ.), SPE-202071-MS, 2020, DOI: https://doi.org/10.2118/202071-MS
13. Bulgakova G.T., Kharisov R.Ya., Sharifullin A.R., Pestrikov A.V., Design optimization of large volume selective acid treatments in carbonate reservoirs (In Russ.), Territoriya Neftegaz, 2010, no. 11, pp. 39-43.
14. Rozovskiy A.Ya., Kinetika topokhimicheskikh reaktsiy (Kinetics of topochemical reactions), Moscow: Khimiya Publ., 1974, 224 p.
15. Vakhrushev S.A., Folomeev A.E., Kotenev Yu.A., Nabiullin R.M., Acid treatment with diverting on carbonate reservoirs of R. Trebs oil field (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2016, no. 4, pp. 112–117.
16. Folomeev A.E., Taipov I.A., Khatmullin A.R. et al., Gelled acid vs. self-diverting systems for carbonate matrix stimulation: an experimental and field study, SPE-206647-MS, 2021, DOI: https://doi.org/10.2118/206647-MS
