Complex bedding effect simulation for hydraulic fracture optimization based on geomechanical modeling

UDK: 550.8.028+550.8.055
DOI: 10.24887/0028-2448-2022-4-26-31
Key words: Lutseyaskhskoe field; Achimov deposits; hydraulic fracture optimization; geomechanical modeling; core study; TIV- anisotropy; complex bedding effect
Authors: R.K. Nepop (PetroGM LLC, RF, Novosibirsk; Institute of Geology and Mineralogy, Siberian Branch of the RAS, RF, Novosibirsk), N.Yu. Smirnov (PetroGM LLC, RF, Novosibirsk), V. Reyes Ahumada (PetroGM LLC, RF, Novosibirsk), M.A. Nizametdinova(PetroGM LLC, RF, Novosibirsk), A.G. Kolyagin (Zarubezhneft JSC, RF, Moscow)

This paper presents the results of comprehensive studies on the Achimov deposits and overlaying clay horizons of Luceyakhskoe field, Western Siberia, aimed at hydraulic fracturing design and optimization. Multidisciplinary investigations included: core testing, 1D/3D Geomechanical modeling and their calibration to earlier hydraulic fracturing results and drilling events, and multivariate calculations of hydraulic fracturing designs. During the study, specific thin bedding was revealed in the silt-clayey sediments of the seal and interlayers. This rock structure is the main reason of differences in rock properties for both: vertical and horizontal directions. The physical and mechanical properties anisotropy of the geological environment can lead to a change in the minimum horizontal stress’s values, which in turn, is one of the main factors that controls the hydraulic fracture geometry. The data correlation obtained within the framework of one project made possible to characterize the complex bedding barrier effect in the seal and interlayer deposits and to be accounted on hydraulic fracture design stage. It was shown that the complex bedding barrier effect has a significant impact on the fracture propagation during hydraulic fracturing. Ignoring this effect in the modeling leads to incorrect calculation of the fracture opening in hydraulic fracturing simulators. At the hydraulic fracturing design optimization, several scenarios were simulated for different combinations of the complex bedding interval’s location, tonnage and horizonal borehole’s depth. Additionally, the selection of the optimal buffer volume and injection rate was performed. As a result of the analysis of more than 1000 hydraulic fracturing design scenarios, 3 basic scenarios were selected for implementation at the Lutseyaskhskoe field, corresponding to different risk levels for an optimal decision making.

References

1. Punanova S.A., Hydrocarbon accumulations of Achimov sediments northern regions of Western Siberia (In Russ.), Ekcpozitsiya Neft' Gaz, 2020, no. 3, pp. 10–13.

2. Borodkin V.N., Kurchikov A.R., To the problem of refining the western and eastern boundaries of the Achimov clinoform complex (West Siberia) (In Russ.), Geologiya i geofizika, 2015, V. 56, no. 9, pp. 1630–1642.

3. Ali A.H.A., Brown T., Delgado R. et al., Watching rocks change-mechanical earth modeling (In Russ.), Oilfield Review, 2003, Summer, V. 15, pp. 22–39.

4. Coussy O., Poromechanics, John Wiley and Sons, 2004, 315 p.

5. Fjar E., Holt R.M., Raaen A.M., Horsrud P., Petroleum related rock mechanics, International Journal of Rock Mechanics and Mining Sciences, 2009, V. 46, no. 8, pp. 1398–1399, https://doi.org/10.1016/j.ijrmms.2009.04.012

6. Warpinski N., Fracture growth in layered and discontinuous media, Proceedings of the Technical Workshops for the Hydraulic Fracturing Study: Fate and Transport, Washington, DC: Environ. Prot. Agency, 2011.

7. Ju W., Wu C., Sun W., Effects of mechanical layering on hydraulic fracturing in shale gas reservoirs based on numerical models, Arabian Journal of Geosciences, 2018, no. 11(12), pp. 1–11, DOI: 10.1007/s12517-018-3693-1

This paper presents the results of comprehensive studies on the Achimov deposits and overlaying clay horizons of Luceyakhskoe field, Western Siberia, aimed at hydraulic fracturing design and optimization. Multidisciplinary investigations included: core testing, 1D/3D Geomechanical modeling and their calibration to earlier hydraulic fracturing results and drilling events, and multivariate calculations of hydraulic fracturing designs. During the study, specific thin bedding was revealed in the silt-clayey sediments of the seal and interlayers. This rock structure is the main reason of differences in rock properties for both: vertical and horizontal directions. The physical and mechanical properties anisotropy of the geological environment can lead to a change in the minimum horizontal stress’s values, which in turn, is one of the main factors that controls the hydraulic fracture geometry. The data correlation obtained within the framework of one project made possible to characterize the complex bedding barrier effect in the seal and interlayer deposits and to be accounted on hydraulic fracture design stage. It was shown that the complex bedding barrier effect has a significant impact on the fracture propagation during hydraulic fracturing. Ignoring this effect in the modeling leads to incorrect calculation of the fracture opening in hydraulic fracturing simulators. At the hydraulic fracturing design optimization, several scenarios were simulated for different combinations of the complex bedding interval’s location, tonnage and horizonal borehole’s depth. Additionally, the selection of the optimal buffer volume and injection rate was performed. As a result of the analysis of more than 1000 hydraulic fracturing design scenarios, 3 basic scenarios were selected for implementation at the Lutseyaskhskoe field, corresponding to different risk levels for an optimal decision making.

References

1. Punanova S.A., Hydrocarbon accumulations of Achimov sediments northern regions of Western Siberia (In Russ.), Ekcpozitsiya Neft' Gaz, 2020, no. 3, pp. 10–13.

2. Borodkin V.N., Kurchikov A.R., To the problem of refining the western and eastern boundaries of the Achimov clinoform complex (West Siberia) (In Russ.), Geologiya i geofizika, 2015, V. 56, no. 9, pp. 1630–1642.

3. Ali A.H.A., Brown T., Delgado R. et al., Watching rocks change-mechanical earth modeling (In Russ.), Oilfield Review, 2003, Summer, V. 15, pp. 22–39.

4. Coussy O., Poromechanics, John Wiley and Sons, 2004, 315 p.

5. Fjar E., Holt R.M., Raaen A.M., Horsrud P., Petroleum related rock mechanics, International Journal of Rock Mechanics and Mining Sciences, 2009, V. 46, no. 8, pp. 1398–1399, https://doi.org/10.1016/j.ijrmms.2009.04.012

6. Warpinski N., Fracture growth in layered and discontinuous media, Proceedings of the Technical Workshops for the Hydraulic Fracturing Study: Fate and Transport, Washington, DC: Environ. Prot. Agency, 2011.

7. Ju W., Wu C., Sun W., Effects of mechanical layering on hydraulic fracturing in shale gas reservoirs based on numerical models, Arabian Journal of Geosciences, 2018, no. 11(12), pp. 1–11, DOI: 10.1007/s12517-018-3693-1


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