SAGD operators are actively installing Inflow Control Devices (ICDs) in their SAGD production wells to enable production at low or ‘negative’ subcool values in order to maximize drawdown, increase fluid production rates and optimize SAGD economics. Operating the wells under higher vapour conditions could expose the ICDs to high velocity steam carrying sand particles, causing erosion and liner failure. A staged approach has been developed for assessing the relative erosion risk of candidate ICDs, including a stage one qualitative assessment, followed by analytical erosion calculations and Computational Fluid Dynamics (CFD) modeling.
In the first stage qualitative assessment, factors such as the anticipated fluid flow path, relative fluid velocity, and ICD housing design are used as inputs to estimate relative erosion rates, identify ICD surfaces where erosion rates are anticipated to be high and to rank ICD candidates based on relative erosion risk. The evaluation of potential erosion risk included consideration of both the predicted erosion severity and the probable consequences of erosive wear, which could include loss of the desired flow control response or damage to the integrity of the body or housing of the ICD. The result of the first stage is a short-list of the top-ranked ICD design candidates.
In the second stage, analytical erosion models are then used to quantify erosion rates on identified target surfaces. Flow velocities and impact angles identified in the first stage are used with analytical flow relationships, such as equations for expansion jets downstream of the flow control elements, as inputs to selected erosion models. The result of this second stage is an updated short list of top-ranked ICD designs.
Finally, coupled solid particle and fluid multiphase CFD simulations are conducted on a small set of ICD design candidates to obtain detailed results on the location and severity of erosion within the flow control element and on all the surfaces of the designs. The results of this stage are specific identification of susceptible erosion surfaces and rates, providing information for the selection of the appropriate ICD design.
At each stage, the number of ICD candidate designs under consideration is reduced. In this manner, simpler methods of analysis (qualitative assessment) may be readily applied to a large number of devices, while more intensive modeling approaches (multiphase CFD) are reserved for a smaller set of design candidates. This approach provides insights into erosion risk based on successively more in-depth analysis methods, including particle paths and erosion locations in the CFD analysis stage which may not be identified using higher-level analytical methods. These results of the CFD analysis could then be used to help improve accuracy when applying analytical erosion models.
Author: Prasad, S., Zahacy, T.
Publisher: SPE Thermal Well Integrity and Design Symposium, Banff, 2018
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