A Slug-Length Distribution Law for Multiphase Transportation Systems

This paper reports on a probabilistic approach which is used to analyze the formation of slugs in nearly horizontal pipelines. Knowledge of the probability amplitude for a liquid bridge in the formation zone allows derivation of the slug-length distribution law. The method is suitable for simulating complex situations, including unsteady flows. For horizontal steady flows, a simple model of this probability, expected to be valid in large-diameter pipes or for long slugs (tail of the distribution), yields a Gaussian law, which is distinct from the log-normal law. Frequency, mean length, and variance depend on only one parameter, which may be predicted from theoretical study (not included here). This new length distribution law is verified against experimental data obtained with an air/water test loop (42 mm in diameter and 400 m long) installed in the Beauplan production laboratory in France and is compared with the log-normal distribution law.