Modelling of cyclic geomechanical treatment of carbonate reservoirs

UDK: 622.276.6
DOI: 10.24887/0028-2448-2021-1-52-56
Key words: cyclic geomechanical treatment, carbonate reservoir, permeability dependence on pressure, micro-fissures, lab experiments, sector models
Authors: D.P. Anikeev (Almetyevsk State Oil Institute, RF, Almetyevsk; Oil and Gas Research Institute of RAS, RF, Moscow), E.S. Zakirov (Almetyevsk State Oil Institute, RF, Almetyevsk; Oil and Gas Research Institute of RAS, RF, Moscow), I.M. Indrupskiy (Almetyevsk State Oil Institute, RF, Almetyevsk; Oil and Gas Research Institute of RAS, RF, Moscow), I.I. Ibragimov (Almetyevsk State Oil Institute, RF, Almetyevsk), R.A. Zakiryanov (Almetyevsk State Oil Institute, RF, Almetyevsk)

The paper summarizes the results of laboratory experiments performed on core samples of two carbonate reservoirs of the Republic of Tatarstan with modeling of real in-situ stresses to assess the dependence of permeability on a cyclic change in pore pressure. Each experiment consisted of 14 pressure stages with two changes in the direction: primary depletion, followed by increase in pressure, and then secondary depletion. At each stage, the permeability was measured for the saturating fluid, and the dynamic values of Poisson's ratio and Young's modulus were obtained by the acoustic method. The behavior of permeability depends both on the initial properties of the samples and saturating fluid. 'Looser' samples with the lowest initial values of Young's modulus showed the strongest permeability reduction during primary depletion. For samples with the highest Young's modulus and the poorest initial reservoir properties, the permeability changed slightly with a decrease in pore pressure. For water-saturated samples, reservoir compaction was recorded as the result of the cyclic change in pressure, most likely associated with plastic deformation of carbonate rock under the influence of water. For hydrocarbon-saturated samples, an increase in permeability during the cyclic geomechanical treatment (CGT) was obtained, ranging from 20% to 3.5 times. For a number of samples, during the increase in pore pressure, an evidence of the formation of a tensile fracture (equivalent to the hydraulic fracturing process) was noted. In all those cases, the value of the fracturing pressure was significantly lower than theoretically estimated which indicates a decrease in rock strength as a result of the previous pressure depletion.

The experimental results were used in flow simulations on sector models of two reservoir elements. Taking into account the dependence of permeability on pressure leads to more heterogeneous distributions of the reservoir pressure and oil recovery. It is shown that in order to assess the potential effect of CGT, appropriate consideration of reservoir compartmentalization and heterogeneity is important. For the sector model of the element with favorable parameters, an increase by 24.6% in cumulative oil production over 10 years was achieved due to the integrated use of CGT.

References

1. Patent SU1609978A1, Method of treating bottom-hole zone of formation, Inventors: Bakirov E.A., Zakirov S.N., Shcherbakov G.A., Kondrat R.M., Panteleev G.V., Fedoseev A.P., Shandrygin A.I.

2. Khristianovich S.A., Kovalenko Yu.F., Kulinich Yu.V., Karev V.I., Increase the productivity of oil wells using the geoloosening (In Russ.), Neft' i gaz Evraziya, 2000, no. 2, pp. 90–94.

3. Patent RU2620099C1, Method of increasing productivity of development wells and injection capacity of injection wells, Inventors: Zakirov S.N., Drozdov A.N., Zakirov E.S., Drozdov N.A., Indrupskij I.M., Anikeev D.P., Ostapchuk S.S. 

4. Patent RU2645684C1, Method of directional loading of the plast, Inventors: Klimov D.M., Karev V.I., Kovalenko Yu.F., Titorov M.Yu.

5. Patent RU2285794C1, Well bottom zone treatment method, Inventors: Karev V.I., Klimov D.M., Kovalenko Ju.F., Kulinich Ju.V., Samokhvalov G.V., Titorov M.Ju.

6. Zakirov S.N., Razrabotka gazovykh, gazokondensatnykh i neftegazokondensatnykh mestorozhdeniy (Development of gas, gas condensate and oil-and-gas condensate fields), Moscow: Struna Publ., 1998, 628 p.

7. Zakirov S.N., Drozdov A.N., Zakirov E.S. et al., Technical and technological aspects of geomechanical impact on the reservoir (In Russ.), Neftegaz.RU, 2018, no. 6, pp. 24–29.

8. Zakirov S.N., Drozdov A.N., Alekseev B.G., Kolobanov A.V., Natural manifestations of geomechanical processes (In Russ.), Nedropol'zovanie XXI vek, 2018, no. 3, pp. 72–77.

9. Khashper A.L., Aminev T.R., Fedorov A.I., Zhonin A.V., Research of dependence of rock permeability on its stress-strain state (In Russ.), Geologicheskiy vestnik, 2019, no. 1, pp. 133–140

10. Karev V.I., Vliyanie napryazhenno-deformirovannogo sostoyaniya gornykh porod na fil'tratsionnyy protsess i debit skvazhin (Influence of the stress-strain state of rocks on the filtration process and well flow rate): thesis of doctor of technical science, Moscow, 2010.

11. Anikeev D.P., Indrupskiy I.M., Zakiryanov R.A., Ibragimov I.I., Otsenka vliyaniya izmeneniya pronitsaemosti ot davleniya na neodnorodnost' drenirovaniya karbonatnogo kollektora (Assessment of the effect of pressure-dependent permeability changes on the heterogeneity of drainage of a carbonate reservoir), Proceedings of VI International Scientific and Practical Conference “Dostizheniya, problemy i perspektivy razvitiya neftegazovoy otrasli” (Achievements, problems and prospects for the development of the oil and gas industry), 16–18 October 2019, Al'met'evsk: Publ. of ASPI, 2019, pp. 33–36.

12. Indrupskiy I.M., Ibragimov I.I., Zakiryanov R.A. et al., Permeability alteration of carbonate reservoir rock under cyclic geomechanical treatment, IOP Conference Series: Materials Science and Engineering, 2020, V. 921, https://doi.org/10.1088/1757-899X/921/1/012009

13. Sylte J.E., Thomas L.K., Rhett D.W. et al., Water induced compaction in the Ekofisk field, SPE-56426-MS, 1999.

14. Ibragimov I.I., Indrupskiy I.M., Lutfullin A.A., Otsenka effekta geomekhanicheskogo vozdeystviya s pomoshch'yu gidrodinamicheskogo modelirovaniya (Assessment of the effect of geomechanical impact using hydrodynamic modeling), Proceedings of V International Scientific and Practical Conference "Dostizheniya, problemy i perspektivy razvitiya neftegazovoy otrasli" (Achievements, problems and prospects for the development of the oil and gas industry), 12 November 2020, Almet'evsk: Publ. of ASPI, 2020.

The paper summarizes the results of laboratory experiments performed on core samples of two carbonate reservoirs of the Republic of Tatarstan with modeling of real in-situ stresses to assess the dependence of permeability on a cyclic change in pore pressure. Each experiment consisted of 14 pressure stages with two changes in the direction: primary depletion, followed by increase in pressure, and then secondary depletion. At each stage, the permeability was measured for the saturating fluid, and the dynamic values of Poisson's ratio and Young's modulus were obtained by the acoustic method. The behavior of permeability depends both on the initial properties of the samples and saturating fluid. 'Looser' samples with the lowest initial values of Young's modulus showed the strongest permeability reduction during primary depletion. For samples with the highest Young's modulus and the poorest initial reservoir properties, the permeability changed slightly with a decrease in pore pressure. For water-saturated samples, reservoir compaction was recorded as the result of the cyclic change in pressure, most likely associated with plastic deformation of carbonate rock under the influence of water. For hydrocarbon-saturated samples, an increase in permeability during the cyclic geomechanical treatment (CGT) was obtained, ranging from 20% to 3.5 times. For a number of samples, during the increase in pore pressure, an evidence of the formation of a tensile fracture (equivalent to the hydraulic fracturing process) was noted. In all those cases, the value of the fracturing pressure was significantly lower than theoretically estimated which indicates a decrease in rock strength as a result of the previous pressure depletion.

The experimental results were used in flow simulations on sector models of two reservoir elements. Taking into account the dependence of permeability on pressure leads to more heterogeneous distributions of the reservoir pressure and oil recovery. It is shown that in order to assess the potential effect of CGT, appropriate consideration of reservoir compartmentalization and heterogeneity is important. For the sector model of the element with favorable parameters, an increase by 24.6% in cumulative oil production over 10 years was achieved due to the integrated use of CGT.

References

1. Patent SU1609978A1, Method of treating bottom-hole zone of formation, Inventors: Bakirov E.A., Zakirov S.N., Shcherbakov G.A., Kondrat R.M., Panteleev G.V., Fedoseev A.P., Shandrygin A.I.

2. Khristianovich S.A., Kovalenko Yu.F., Kulinich Yu.V., Karev V.I., Increase the productivity of oil wells using the geoloosening (In Russ.), Neft' i gaz Evraziya, 2000, no. 2, pp. 90–94.

3. Patent RU2620099C1, Method of increasing productivity of development wells and injection capacity of injection wells, Inventors: Zakirov S.N., Drozdov A.N., Zakirov E.S., Drozdov N.A., Indrupskij I.M., Anikeev D.P., Ostapchuk S.S. 

4. Patent RU2645684C1, Method of directional loading of the plast, Inventors: Klimov D.M., Karev V.I., Kovalenko Yu.F., Titorov M.Yu.

5. Patent RU2285794C1, Well bottom zone treatment method, Inventors: Karev V.I., Klimov D.M., Kovalenko Ju.F., Kulinich Ju.V., Samokhvalov G.V., Titorov M.Ju.

6. Zakirov S.N., Razrabotka gazovykh, gazokondensatnykh i neftegazokondensatnykh mestorozhdeniy (Development of gas, gas condensate and oil-and-gas condensate fields), Moscow: Struna Publ., 1998, 628 p.

7. Zakirov S.N., Drozdov A.N., Zakirov E.S. et al., Technical and technological aspects of geomechanical impact on the reservoir (In Russ.), Neftegaz.RU, 2018, no. 6, pp. 24–29.

8. Zakirov S.N., Drozdov A.N., Alekseev B.G., Kolobanov A.V., Natural manifestations of geomechanical processes (In Russ.), Nedropol'zovanie XXI vek, 2018, no. 3, pp. 72–77.

9. Khashper A.L., Aminev T.R., Fedorov A.I., Zhonin A.V., Research of dependence of rock permeability on its stress-strain state (In Russ.), Geologicheskiy vestnik, 2019, no. 1, pp. 133–140

10. Karev V.I., Vliyanie napryazhenno-deformirovannogo sostoyaniya gornykh porod na fil'tratsionnyy protsess i debit skvazhin (Influence of the stress-strain state of rocks on the filtration process and well flow rate): thesis of doctor of technical science, Moscow, 2010.

11. Anikeev D.P., Indrupskiy I.M., Zakiryanov R.A., Ibragimov I.I., Otsenka vliyaniya izmeneniya pronitsaemosti ot davleniya na neodnorodnost' drenirovaniya karbonatnogo kollektora (Assessment of the effect of pressure-dependent permeability changes on the heterogeneity of drainage of a carbonate reservoir), Proceedings of VI International Scientific and Practical Conference “Dostizheniya, problemy i perspektivy razvitiya neftegazovoy otrasli” (Achievements, problems and prospects for the development of the oil and gas industry), 16–18 October 2019, Al'met'evsk: Publ. of ASPI, 2019, pp. 33–36.

12. Indrupskiy I.M., Ibragimov I.I., Zakiryanov R.A. et al., Permeability alteration of carbonate reservoir rock under cyclic geomechanical treatment, IOP Conference Series: Materials Science and Engineering, 2020, V. 921, https://doi.org/10.1088/1757-899X/921/1/012009

13. Sylte J.E., Thomas L.K., Rhett D.W. et al., Water induced compaction in the Ekofisk field, SPE-56426-MS, 1999.

14. Ibragimov I.I., Indrupskiy I.M., Lutfullin A.A., Otsenka effekta geomekhanicheskogo vozdeystviya s pomoshch'yu gidrodinamicheskogo modelirovaniya (Assessment of the effect of geomechanical impact using hydrodynamic modeling), Proceedings of V International Scientific and Practical Conference "Dostizheniya, problemy i perspektivy razvitiya neftegazovoy otrasli" (Achievements, problems and prospects for the development of the oil and gas industry), 12 November 2020, Almet'evsk: Publ. of ASPI, 2020.


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