Oil-Rate Prediction Model for the Ramp-up Phase of a Steam-Assisted-Gravity-Drainage Process: Stability Approach
- Mazda Irani (Ashaw Energy)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- June 2019
- Document Type
- Journal Paper
- 1,016 - 1,036
- 2019.Society of Petroleum Engineers
- rising phase, SAGD, steam fingering, instability, ramp-up
- 24 in the last 30 days
- 78 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 10.00|
|SPE Non-Member Price:||USD 30.00|
In a steam-assisted-gravity-drainage (SAGD) process, the steam chamber starts to develop in three stages: ramp up, lateral spreading, and wind down. Although the physics of ramp up (or the rising phase) is completely different from that of lateral spreading, the current theoretical analyses of SAGD use a similar approach for modeling lateral spreading to calculate the ramp-up oil rate. The oil rate at the ramp-up phase is highly dependent upon the upward growth of the steam chamber, which is controlled by the frontal instability of the steam-condensate front into the heated bitumen. In this study, the evolution of disturbance (spatial-growth rate) was explored by solving the initial value problem governing the linear stability of the pressure and water-phase velocity normal to the edge of the steam chamber found in the SAGD process. To investigate the interaction of the steam chamber/reservoir zones, a new model was formulated that coupled the pressure diffusion equations and condensate leakoff into a reservoir beyond the chamber. The results suggested that the steam interface in the SAGD process was unstable if it moved faster than the critical velocity. In the ramp-up phase, the velocity at the chamber interface increased until it reached the instability velocity. Once it was reached, the instability caused extensive mixing and convection that reduced the temperature at the interface, thus causing the interface velocity to reduce to the instability velocity. As a result, the interface grew at the equilibrium velocity of minimum instability velocity (or critical velocity). The vertical/horizontal permeability ratio of the reservoir is a controlling parameter of instability. The calculated oil-production rate at ramp up increases linearly with time, which contradicts Butler's ramp-up formula that states that rate is correlated to the cubic root of time. Another key finding was that the suggested ramp-up-rate formula was highly dependent upon the reservoir-water mobility, which was supported by field operations in reservoirs with high water mobility such as Suncor/Firebag and Nexen/Long Lake, where the ramp-up time was significantly less than that in reservoirs with low water mobility, such as those in the MacKay River Field.
|File Size||1 MB||Number of Pages||21|
Andronov, A. A., Vitt, A. A., and Khaikin, S. E. 1966. Theory of Oscillators, translated from the Russian by F. Immirzi, edited and abridged by W. Fishwick. Oxford: Pergamon Press.
Butler, R. M. 1987. Rise of Interfering Steam Chambers. J Can Pet Technol 26 (3): 70–75. PETSOC-87-03-07. https://doi.org/10.2118/87-03-07.
Butler, R. M. 1991. Thermal Recovery of Oil and Bitumen. Englewood Cliffs, New Jersey: Prentice Hall.
Butler, R. M. 1994. Horizontal Wells for the Recovery of Oil, Gas and Bitumen, Vol. 1, 169–199. Richardson, Texas: Monograph Series, SPE.
Butler, R. M. and Stephens, D. J. 1981. The Gravity Drainage of Steam-Heated Heavy Oil to Parallel Horizontal Wells. J Can Pet Technol 20 (2): 90–96. PETSOC-81-02-07. https://doi.org/10.2118/81-02-07.
Gotawala, D. R. and Gates, I. D. 2011. Stability of the Edge of a SAGD Steam Chamber in a Bitumen Reservoir. Chem Eng Sci 66: 1802–1809. https://doi.org/10.1016/j.ces.2011.01.025.
Hopf, E. 1942. Abzweigung einer periodischen Lösung von einer stationären Lösung eines Differentialsystems, Berichten der Mathematisch-Physischen Klasse der Sächsischen Akademie der Wissenschaften zu Leipzig XCIV, 1–22. In The Hopf Bifurcation and Its Applications, J.E. Marsden and M. McCracken, Sec. 5 (English translation with comments). New York: Springer-Verlag, 1976.
Irani, M. and Cokar, M. 2016. Discussion on the Effects of Temperature on Thermal Properties in the Steam-Assisted-Gravity-Drainage (SAGD) Process. Part 1: Thermal Conductivity. SPE J. 21 (2): 334–352. SPE-178426-PA. https://doi.org/10.2118/178426-PA.
Irani, M. and Gates, I. D. 2013. Understanding the Convection Heat-Transfer Mechanism in Steam-Assisted-Gravity-Drainage Process. SPE J. 18 (6): 1202–1215. SPE-167258-PA. https://doi.org/10.2118/167258-PA.
Irani, M. and Gates, I. D. 2014. On the Stability of the Edge of a Steam-Assisted-Gravity-Drainage Steam Chamber. SPE J. 19 (2): 280–288. SPE-167260-PA. https://doi.org/10.2118/167260-PA.
Irani, M. and Gates, I. D. 2016. Drained/Undrained Zones Boundary in Steam-Assisted Gravity Drainage Process. SPE J. 21 (5): 1721–1742. SPE-174417-PA. https://doi.org/10.2118/174417-PA.
Irani, M. and Ghannadi, S. 2013. Understanding the Heat-Transfer Mechanism in the Steam-Assisted Gravity-Drainage (SAGD) Process and Comparing the Conduction and Convection Flux in Bitumen Reservoirs. SPE J. 18 (1): 134–145. SPE-163079-PA. https://doi.org/10.2118/163079-PA.
Ito, Y. and Ipek, G. 2005. Steam Fingering Phenomenon During SAGD Process. Presented at the SPE International Thermal Operations and Heavy Oil Symposium, Calgary, 1–3 November. SPE-97729-MS. https://doi.org/10.2118/97729-MS.
Zargar, Z. and Farouq Ali, S. M. 2018. Comprehensive Multi-Stage Analytical Treatment of Steam-Assisted Gravity Drainage SAGD. Presented at the SPE Annual Technical Conference and Exhibition, Dallas, 24–26 September. SPE-191533-MS. https://doi.org/10.2118/191533-MS.