Experimental and modeling studies of gas-liquid flow in vertical pipes at high superficial gas velocities

In many oilfield applications, gas-liquid (GL) flow modeling is required. One of these applications is predicting the uncontrolled hydrocarbon flow through a wellbore after a blowout, referred to as the worst-case discharge rate (WCD rate). It is common to see annular flow patterns in a wellbore during a blowout, especially when the superficial gas velocity (Vsg) is high and the superficial liquid velocity (Vsl) is low to moderate. As a result, accurate predictions of WCD rates require a better understanding of annular flow characteristics. Thus, this study is conducted with an annular flow pattern, maintaining Vsg between 8 and 120 m/s and Vsl between 0.25 and 0.96 m/s.

The analysis of the experimental measurements shows the establishment of an annular flow pattern with pressure drop (Δp) that increases with the in-situ Vsg at a constant Vsl. Moreover, the liquid holdup (H_L) reduced sharply with the Vsg at a constant liquid rate. Furthermore, a new mechanistic GL flow model is formulated based on an existing model and correlations. Finally, measurements are compared with the forecasts of the new and existing models and commercial software. It is shown that the new model provides a more precise forecast of Δp than the existing software and models.