In this paper we perform a comprehensive analysis of two- and three-phase large scale experimental data from the SINTEF Multiphase Laboratory on low liquid loading flows. The experimental work was financed by Statoil (" Experiments for low liquid loading with liquid holdup discontinuities in two- and three-phase flows" [1]), addressing key flow assurance challenges in the gas condensate field development offshore Tanzania [2]. In the present work we use this new data for the purpose of improving the predictions of LedaFlow. In particular, we are interested in predicting the discontinuous onset of liquid accumulation (due to multiple holdup solutions) for large diameter pipes, which is a very important matter for many wet-gas transport systems. We demonstrate that the current data enables calculation of the interfacial friction factor with unprecedented accuracy for a wide range of parameters. This is important because the interfacial friction is the most crucial model in these circumstances, and ordinarily it has also been the most uncertain closure in multiphase flow models. We show that by calibrating the interfacial friction model to this data, LedaFlow is able to predict the onset of liquid accumulation with remarkable accuracy for three different pipe diameters (4", 8" and 12"), indicating that the model has good scaling abilities. Finally, we show that the prevailing LedaFlow-predictions of holdup and pressure drop also become very accurate for these types of conditions.
This paper summarizes the work performed with respect to closure improvements in LedaFlow for low liquid loading conditions in moderately inclined pipes, with particular emphasis on predicting the onset of liquid accumulation. Here, " low liquid loading" is taken to mean low liquid flow rates, typically USL≤0.01 m/s.
