Estudo experimental de intermitência severa em um sistema água-ar.

Abstract

The objective of this work is to do an experimental study of the severe slugging phenomenon in the pipeline-riser system of the Multipurpose Multiphase Flow Laboratory by using the fluids air and water. Severe slugging may occur for low flow rates in pipeline-riser systems where a downward pipeline is followed by a vertical riser. In this phenomenon there is liquid accumulation at the bottom of the riser resulting in production losses due to the great fluctuations of pressure and flow rate during its cycles which may last for hours depending on the length of the system. The high pressure values can also cause shutdown of the platform separation system. The first stage of this study was to define the experimental procedure to be adopted. It was necessary to perform a calibration of the orifice plates in order to have a precise control of the gas mass flow rate. The experimental results were divided in stable and unstable cases. The instability is defined by the presence of pressure oscillations at the bottom of the riser. Stability maps were created to compare the stabiliy curve obtained by the stability linear theory with the experimental results. The experimental pressure oscillations were compared with two numerical models. The pressure variation at the separator was studied to verify the mitigation effects during unstable and/or severe slugging conditions.