Hydraulic modeling is an integral part of any MPD operation. Engineers rely on hydraulic flow modeling throughout an MPD project; i.e., during the candidate selection for the MPD well, the initial design, and, during the MPD operation. Hence, choosing the correct hydraulics model is critical to the success of an MPD project.

This paper proposes that the correct hydraulics model for a particular well depends on the nature of the reservoir and bottomhole conditions. Although, the data for simulation often comes from offset wells and may not be representative of the target well. Additionally the same hydraulics model may not work for different well conditions; e.g., a model that works for a two-phase drilling fluid may not work successfully for a high-density oil-based mud (OBM). Hence, an engineer should run flow models using different simulators and conclude the best possible model for the specific conditions.

The paper discusses two hydraulic models that were used in offshore India. Calibration of these models was done using data from offset wells. It was found that the models predicted different results with the same inputs. While one gave more realistic results on comparison with the post drilling reports on the offset wells, the other model did not match the results. On further analysis, it was found that the reason for failure of the second model was its inaccuracy in simulating high-density OBM; also, each software handled cuttings transport, geometry, and rheological behaviour differently. The paper compares these differences and discusses the type and range of applications for which each is most applicable.

The results conclude that a hydraulic model is case sensitive. An in-depth analysis of both models, the reasons for failure and success of each, and how using the correct hydraulics model can significantly influence the MPD operation will be presented.

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