Terrain Slugging in a High-Pressure Pipeline-Riser System - Large Scale Experiments and Predictions With LedaFlow

The present work aims at investigating the performance of the LedaFlow multiphase simulator for transient terrain slugging scenarios. A number of two-phase riser slugging experiments performed at the SINTEF Large Scale Multiphase Laboratory are analyzed and simulated with LedaFlow. The experiments were conducted in an 8-inch pipe using Diesel and Nitrogen as fluids at pressures between 20 and 50 bar. The pipe geometry is approximately 423 meters long, and includes a 50 meter long "bump", a 65 meter declined pipe (-2 degrees) and a 54 meter long riser at the end. The gas supply line was 416 m long providing an upstream gas volume that gives extra compressibility to the system, facilitating liquid accumulation at the riser base and subsequent terrain slugging. The experiments show that at constant gas flow rates, the severity/amplitude of the slugging in the riser increases to a maximum at a superficial liquid velocity around 0.5–1 m/s (depending on the conditions), and then decreases to zero as the liquid flow rate is further increased. The experiments are reproduced well by the LedaFlow simulations, both in terms of pressure amplitudes and slugging periods.