Two-phase flow transient simulation of severe slugging in pipeline-risers systems

Abstract

Pipeline-risers systems are frequently encountered in the petroleum industry, especially in the offshore platforms. Single-phase flow does not involve significant troubles in the operations through these arrangements. However, during multiphase flow, flooding of the separation facilities could be expected due to the generation of severe slugs at the bottom of the riser. The size and frequency of the slugs are functions of the accumulation and displacement of liquid at the base of the riser and can be controlled with an adequate model. An improved transient model is presented to simulate severe slugging phenomenon in pipeline-risers systems. Gas penetration is described thoroughly since the first bubble penetrates into the riser until it reaches the top of it. The model presents improvements in the characteristics method applications including a correction for the gas density deviation caused by the nonfixed space-time resolution during the gas penetration. The results were compared with experimental data and previous models showing better accuracy. The model can be used to design new pipeline riser-systems or to adjust the operation of existing systems to prevent the occurrence of severe slug flow.

Model for Terrain-Induced Slug Flow for High Viscous Liquids

“…This paper introduces and extends a model for the study of the phenomenon of the severe or terrain slugging. This model adapts the work of Hernandez [6] viscous effects of the liquid phase.…”

“…Sarica & Shoham [5] developed a simplified model for transient severe slug. Hernandez et al [6] proposed corrections to the mechanistic model proposed by Sarica & Shoham [5] on the calculation of the liquid density through the method of characteristics.…”

“…On this work, the drift flux model of Fabre et al [4] is extended to take into account the liquid viscosity and riser angle inclination. The improvements and corrections proposed by Sarica & Shoham [5] and by Hernandez et al [6] were taken into account. A sensitivity analysis of the liquid viscosity and riser angle inclination is performed aiming to recognize the difference on the severe and terrain slugging behaviour when operating with viscous flows.…”