Riser Base Jumper Slugging Analysis by CFD Simulations

Abstract

Slugging is one of the operational hazards of subsea pipelines associated with the transportation of multiphase fluids. Such phenomenon can results in cyclic loading in the lines, leading to fatigue damage or high stress (possible strength concern) that need to be considered in the design process. However, there is a real lack in the literature of clear guidance addressing the way of investigation of such possible Flow Induced Vibration (FIV) issue. One solution is to perform Fluid Structure Interaction (FSI) analysis. However, for this purpose, it appears fundamental to recover at the best the main flow features that develop in characteristic piping systems. Depending on the flow conditions, on the line path configuration, slug can be disturbed, dissociated and consequently results in multi-scale flow that could become an additional source of fatigue. Riser Base Jumper (RBJ) in M-shape configuration, due to its complex geometry can be prone to such multi scale-flow and should be consequently treated with particular attention. The proposed paper aims to improve the understanding of the main flow features that accompany slug flow in a RBJ. It is proposed to use Computational Multiphase Fluid Dynamic (CMFD) to this end. The main objective of the analysis is to characterise at the best the different expected pressure variations and the related excitation frequencies.