Industry experience indicates the vast majority of well failures in SAGD wells occur in the liner, and most of these appear to be related to a loss of subcool control. This paper presents an example of how two factors, well trajectory and reservoir performance, can combine to produce problems with subcool control that are difficult to discern under normal operation and likely to lead to a steam breakthrough event. Simulation of steam trap conformance is an important tool for optimizing SAGD efficiency, but it can also be instrumental for diagnosing, avoiding, and resolving subcool control issues. To be effective, the simulator must account for the parameters that govern conformance, which include reservoir performance, well geometry, reservoir properties, completion details, and operational controls. This example employs a rigorous simulation basis that captures the contributions of both injection well hydraulics and production well hydraulics to steam trap conformance, or the lack thereof. The example demonstrates how enhanced monitoring systems and procedures can be used to diagnose subcool control problems before a failure results. Furthermore, various mitigation strategies are explored to alleviate the subcool control problem and facilitate more efficient SAGD operation. The mitigation strategies include changes to the initial well design, such as customized injector or producer liners. The simulation basis enables the mitigation strategies to be assessed based on the uniformity and stability of the liquid level above the production well. The simulation results reveal different levels of effectiveness between the various mitigation options. This paper provides new insight into how factors like well trajectory and reservoir performance can compromise subcool control and explores creative solutions for improving SAGD performance.

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