Integrated technology for influencing kerogen-containing strata of the Bazhenov formation

UDK: 622.276.6Пр.М
DOI: 10.24887/0028-2448-2020-3-14-17
Key words: Bazhenov formation, electric heating cable, CO2 injection, Huff-n-Puff technology
Authors: L.N. Nazarova (Gubkin University, RF, Moscow), D.S. Skorov (Gubkin University, RF, Moscowж PETEС Ltd., RF, Moscow)

Particular attention is paid both in Russia and in the world to the development of fields with unconventional oil resources, which include kerogen-containing strata of the Bazhenov formation, spread over an area of more than

1 mln km2. According to various estimates, the potential of the Bazhenov formation is up to 100 billion tons, not taking into account the hydrocarbon resource of kerogen. The development of such deposits is complicated by a number of factors: a complex, heterogeneous geological structure, low permeability, abnormally high reservoir pressures and temperatures, and the content of solid organic matter.

Given the high degree of enrichment with kerogen (according to various estimates, up to 28 %), the uneven distribution in volume, the development of the Bazhenov formation should differ significantly from traditional methods. Along with existing technologies that describe such development approaches as multi-stage hydraulic fracturing, method of thermal gas treatment, we proposed and tested using the CMG STARS hydrodynamic simulator the technology for the Bazhenov formation development, which assumes a complex effect on the formation. The method include of two stages. The first stage is heating the formation with an electric cable lowered into a horizontal well in order to form a primary system of interconnected microcracks in the kerogen matrix to increase injectivity and cover the formation with subsequent exposure. In addition, heating leads to the onset of thermal conversion of kerogen. At the second stage, cyclic injection of carbon dioxide by Huff-n-Puff technology is implemented in the following mode: injection – soak period – production. Injected CO2 works to dissolve kerogen and partially maintain reservoir pressure, which leads to the formation of mobile hydrocarbons and increased formation coverage due to the formation of a secondary system of microcracks. According to the calculation results, the cumulative oil production and gas injection in surface conditions after just over two years of implementation of the Huff-n-Puff technology amounted to 10,200 m3 and 2.03 mln m3, respectively. Cumulative production of carbon dioxide in the periods of production selection is 622,000 m3, which is 31 % of the accumulated injection.

References

1. Shchekoldin K.A., Obosnovanie tekhnologicheskikh rezhimov termogazovogo vozdeystviya na zalezhi bazhenovskoy svity (Substantiation of technological modes of thermogas effect on deposits of the Bazhenov formation): thesis of doctor of technical science, Moscow, 2016.

2. Nikitina E.A., Kuz'michev A.N., Charuev S.A., Tolokonskiy S.I., Experimental estimation for the quantity of additionally produced oil during low-temperature pyrolysis of kerogen-containing rock (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2017, no. 12, pp. 132–134.

3. Shakhmaev A.M. et al., Numerical evaluation of the wet combustion efficiency of the thermal gas tehnology on a 2D model (In Russ.), Ekspozitsiya Neft' Gaz, 2018, no. 2, pp. 47–50.

4.  Morariu D., Aver'yanova O.Yu., Some aspects of oil shale: conceptual framework, the possibility of evaluation and the search for oil recovery technologies (In Russ.), Neftegazovaya litologiya. Teoriya i praktika, 2013, V. 8, no. 1.

5. Khlebnikov V.N. et al., The study of hydrothermal influence on the Bazhenov formation breed (In Russ.), Bashkirskiy khimicheskiy zhurnal, 2011, no. 4, pp. 182–187.

6. Yu Wey et al., Simulation Study of CO2 huff-n-puff process in Bakken tight oil reservoirs, SPE-169575-MS, 2014, https://doi.org/10.2118/169575-MS.

7. Alharty N. et al., Enhanced oil recovery in liquid-rich oil shale reservoirs: Laboratory to field, SPE-175034-PA, 2015, https://doi.org/10.2118/175034-PA.

8. Tiika L. et al., Formation of the thermobitumen from oil shale by low-temperature pyrolysis in an autoclave, Oil shale, 2007, no. 4, pp. 535 – 546.

9. Keaney G.M. et al., Thermal damage and the evolution of crack connectivity and permeability in ultra-low permeability rocks, Proceedings of 6th North America Rock Mechanics Symposium (NARMS): Rock Mechanics Across Borders and Disciplines, Houston, Texas, USA, 2004.

10. Khamidullin R.A. et al., The reservoir properties of the rocks of the bazhenovskaya formation (In Russ.), Vestnik Moskovskogo Universiteta. Ser. 4. Geologiya = Moscow University Geology Bulletin, 2013, no. 5, pp. 57–64.

11. Pribylov A.A., Skibitskaya N.A., Zekel' L.A., Sorption of methane, ethane, propane, butane, carbon dioxide, and nitrogen on kerogen (In Russ.), Zhurnal fizicheskoy khimii = Russian Journal of Physical Chemistry A., 2014, no. 6, pp. 1043–1051.

12. Lifshits S.Kh., Chalaya O.N., Possible mechanism of oil formation in the flow of supercritical fluid illustrated by carbon dioxide (In Russ.), Sverkhkriticheskie Flyuidy: Teoriya i Praktika, 2010, no. 2, pp. 45–55.

13. Shakhmaev A.M. et al., Numerical implementation of the thermal gas technology mechanism in the 2D model  (In Russ.), Ekspozitsiya Neft' Gaz, 2018, no. 1 (61), pp. 39–45.

14. Erofeev A.A. et al., Simulation of thermal recovery methods for development of the Bazhenov formation (In Russ.), SPE-182131-RU, 2016, https://doi.org/10.2118/182131-RU.

15. Mukhina E. et al., Hydrocarbon saturation for an unconventional reservoir in details (In Russ.), SPE-196743-RU, 2019, https://doi.org/10.2118/196743-RU.

Particular attention is paid both in Russia and in the world to the development of fields with unconventional oil resources, which include kerogen-containing strata of the Bazhenov formation, spread over an area of more than

1 mln km2. According to various estimates, the potential of the Bazhenov formation is up to 100 billion tons, not taking into account the hydrocarbon resource of kerogen. The development of such deposits is complicated by a number of factors: a complex, heterogeneous geological structure, low permeability, abnormally high reservoir pressures and temperatures, and the content of solid organic matter.

Given the high degree of enrichment with kerogen (according to various estimates, up to 28 %), the uneven distribution in volume, the development of the Bazhenov formation should differ significantly from traditional methods. Along with existing technologies that describe such development approaches as multi-stage hydraulic fracturing, method of thermal gas treatment, we proposed and tested using the CMG STARS hydrodynamic simulator the technology for the Bazhenov formation development, which assumes a complex effect on the formation. The method include of two stages. The first stage is heating the formation with an electric cable lowered into a horizontal well in order to form a primary system of interconnected microcracks in the kerogen matrix to increase injectivity and cover the formation with subsequent exposure. In addition, heating leads to the onset of thermal conversion of kerogen. At the second stage, cyclic injection of carbon dioxide by Huff-n-Puff technology is implemented in the following mode: injection – soak period – production. Injected CO2 works to dissolve kerogen and partially maintain reservoir pressure, which leads to the formation of mobile hydrocarbons and increased formation coverage due to the formation of a secondary system of microcracks. According to the calculation results, the cumulative oil production and gas injection in surface conditions after just over two years of implementation of the Huff-n-Puff technology amounted to 10,200 m3 and 2.03 mln m3, respectively. Cumulative production of carbon dioxide in the periods of production selection is 622,000 m3, which is 31 % of the accumulated injection.

References

1. Shchekoldin K.A., Obosnovanie tekhnologicheskikh rezhimov termogazovogo vozdeystviya na zalezhi bazhenovskoy svity (Substantiation of technological modes of thermogas effect on deposits of the Bazhenov formation): thesis of doctor of technical science, Moscow, 2016.

2. Nikitina E.A., Kuz'michev A.N., Charuev S.A., Tolokonskiy S.I., Experimental estimation for the quantity of additionally produced oil during low-temperature pyrolysis of kerogen-containing rock (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2017, no. 12, pp. 132–134.

3. Shakhmaev A.M. et al., Numerical evaluation of the wet combustion efficiency of the thermal gas tehnology on a 2D model (In Russ.), Ekspozitsiya Neft' Gaz, 2018, no. 2, pp. 47–50.

4.  Morariu D., Aver'yanova O.Yu., Some aspects of oil shale: conceptual framework, the possibility of evaluation and the search for oil recovery technologies (In Russ.), Neftegazovaya litologiya. Teoriya i praktika, 2013, V. 8, no. 1.

5. Khlebnikov V.N. et al., The study of hydrothermal influence on the Bazhenov formation breed (In Russ.), Bashkirskiy khimicheskiy zhurnal, 2011, no. 4, pp. 182–187.

6. Yu Wey et al., Simulation Study of CO2 huff-n-puff process in Bakken tight oil reservoirs, SPE-169575-MS, 2014, https://doi.org/10.2118/169575-MS.

7. Alharty N. et al., Enhanced oil recovery in liquid-rich oil shale reservoirs: Laboratory to field, SPE-175034-PA, 2015, https://doi.org/10.2118/175034-PA.

8. Tiika L. et al., Formation of the thermobitumen from oil shale by low-temperature pyrolysis in an autoclave, Oil shale, 2007, no. 4, pp. 535 – 546.

9. Keaney G.M. et al., Thermal damage and the evolution of crack connectivity and permeability in ultra-low permeability rocks, Proceedings of 6th North America Rock Mechanics Symposium (NARMS): Rock Mechanics Across Borders and Disciplines, Houston, Texas, USA, 2004.

10. Khamidullin R.A. et al., The reservoir properties of the rocks of the bazhenovskaya formation (In Russ.), Vestnik Moskovskogo Universiteta. Ser. 4. Geologiya = Moscow University Geology Bulletin, 2013, no. 5, pp. 57–64.

11. Pribylov A.A., Skibitskaya N.A., Zekel' L.A., Sorption of methane, ethane, propane, butane, carbon dioxide, and nitrogen on kerogen (In Russ.), Zhurnal fizicheskoy khimii = Russian Journal of Physical Chemistry A., 2014, no. 6, pp. 1043–1051.

12. Lifshits S.Kh., Chalaya O.N., Possible mechanism of oil formation in the flow of supercritical fluid illustrated by carbon dioxide (In Russ.), Sverkhkriticheskie Flyuidy: Teoriya i Praktika, 2010, no. 2, pp. 45–55.

13. Shakhmaev A.M. et al., Numerical implementation of the thermal gas technology mechanism in the 2D model  (In Russ.), Ekspozitsiya Neft' Gaz, 2018, no. 1 (61), pp. 39–45.

14. Erofeev A.A. et al., Simulation of thermal recovery methods for development of the Bazhenov formation (In Russ.), SPE-182131-RU, 2016, https://doi.org/10.2118/182131-RU.

15. Mukhina E. et al., Hydrocarbon saturation for an unconventional reservoir in details (In Russ.), SPE-196743-RU, 2019, https://doi.org/10.2118/196743-RU.
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