On Subcool Control in Steam-Assisted-Gravity-Drainage Producers—Part I: Stability Envelopes
- Mazda Irani (University of Calgary and Ashaw Energy)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- June 2018
- Document Type
- Journal Paper
- 841 - 867
- 2018.Society of Petroleum Engineers
- steam trap control, Steam-Assisted Gravity Drainage, steam breakthrough limit, subcool, temperature observation wells
- 11 in the last 30 days
- 253 since 2007
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Steam-assisted-gravity-drainage (SAGD) industry experience indicates that the majority of producer workovers occur because of liners or electrical submersible pumps (ESPs), and both failures appear to result from inefficient “steam-trap control.” Thermodynamic steam-trap control, also termed “subcool control,” is a typical operation strategy for most SAGD wells. Simply, subcool (or reservoir subcool vs. pump subcool) is the temperature difference between the steam chamber (or injected steam) and the produced fluid. The main objective is to keep subcool higher than a set value that varies between 0 to 40° and even higher values.
This study presents a method to calculate the liquid-pool level from the temperature profile in observation wells, and liquid-pool shrinkage as a function of time. Unfortunately, it is not practical to monitor the liquid level by having observation wells for every SAGD well pair. For this reason, the algebraic equation for liquid-pool depletion on the basis of wellbore-drawdown, subcool, and emulsion productivity is generated. By use of this equation, the envelopes are suggested to differentiate three different regimes: “stable production,” “liquid-pool depletion,” and “steam-breakthrough limit.” Gas lift operations such as the MacKay River thermal project suggested that envelopes for constant wellbore drawdown are not practical. Therefore, the steam-breakthrough limit is defined for constant rate, which is more consistent in gas lift operations. In this study, the steam-breakthrough limit is validated for operation data from the MacKay River. This study provides a new insight into how factors such as production rate and wellbore drawdown can compromise subcool control and cause steam breakthrough, and how liquid-pool depletion may result in uncontrolled steam coning at long time.
As a part of this study, a minimum-subcool concept (or target reservoir subcool) is presented as a function of skin and pressure drawdown. It is shown that the minimum subcool is highly dependent on the maturity of steam-chamber and underburden heat loss especially for zero-skin producers. The results of this work emphasize that the target subcool on the producer should increase slightly with chamber maturity, considering that the skin is nonzero for most SAGD producers.
|File Size||1 MB||Number of Pages||27|
Butler, R. M. 1991. Thermal Recovery of Oil and Bitumen. Englewood Cliffs, New Jersey: Prentice Hall.
Butler, R. M. 1992. Gravity Drainage to Horizontal Wells. J Can Pet Technol 31 (4): 31–37. SPE-92-04-02-PA. https://doi.org/10.2118/92-04-02-PA.
Butler, R. M. 1994. Horizontal Wells for the Recovery of Oil, Gas, and Bitumen, ed. Betty Dargie. 228 pages. Calgary: Petroleum Society of the Canadian Institute of Mining, Metallurgy and Petroleum.
Edmunds, N. R. 2000. Investigation of SAGD Steam Trap Control in Two and Three Dimensions. J Can Pet Technol 39 (1): 30–40. PETSOC-00-01-02. https://doi.org/10.2118/00-01-02.
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.
Ito, Y. and Suzuki, S. 1999. Numerical Simulation of the SAGD Process in the Hangingstone Oil Sands Reservoir. J Can Pet Technol 38 (9): 27–35. PETSOC-99-09-02. https://doi.org/10.2118/99-09-02.
Ivory, J. J., Zheng, R., Nasr, T. N. et al. 2008. Investigation of Low-Pressure ES-SAGD. Presented at the International Thermal Operations and Heavy Oil Symposium, Calgary, 20–23 October. SPE-117759-MS. https://doi.org/10.2118/117759-MS.
Kaiser, T. M. V. and Taubner, S. P. 2014. Method for Controlling Fluid Interface Level in Gravity Drainage Oil Recovery Processes With Crossflow. US 20140083692 A1. Noetic Technologies Inc.
Kisman, K. E. 2003. Artificial Lift—A Major Unresolved Issue for SAGD. J Can Pet Technol 42 (8): 39–45. PETSOC-03-08-02. https://doi.org/10.2118/03-08-02.
Mukherjee, N. J., Gittins, S. D., Edmunds, N. R. et al. 1995. Comparison of Field Versus Forecast Performance for Phase B of the UTF SAGD Project in the Athabasca Oil Sands. Presented at the 6th UNITAR International Conference on Heavy Crude and Tar Sands, Houston, 12–17 February.
Muskat, M. 1937. The Flow of Homogeneous Fluids Through Porous Media, first edition. New York: McGraw-Hill.
Peaceman, D. W. 1983. Interpretation of Well-Block Pressures in Numerical Reservoir Simulation With Nonsquare Grid Blocks and Anisotropic Permeability. SPE J. 23 (3): 531–543. SPE-10528-PA. https://doi.org/10.2118/10528-PA.
Taubner, S. P., Lipsett, M. G., Keller, A. et al. 2016. Gravity Inflow Performance Relationship for SAGD Production Wells. Presented at the SPE Canada Heavy Oil Technical Conference, Calgary, 7–9 June. SPE-180714-MS. https://doi.org/10.2118/180714-MS.
Yang, Y., Huang, S., Liu, Y. et al. 2017. A Multistage Theoretical Model to Characterize the Liquid Level During Steam-Assisted-Gravity-Drainage Process. SPE J. 22 (1): 327–338. SPE-183630-PA. https://doi.org/10.2118/183630-PA.
Yuan, J. Y. and Nugent, D. 2013. Subcool, Fluid Productivity, and Liquid Level Above a SAGD Producer. J Can Pet Technol 52 (2): 360–367. SPE-157899-PA. https://doi.org/10.2118/157899-PA.