Flow-Induced Vibration of a Reversed U-Shaped Jumper Conveying Oil-Gas Two-Phase Flow

Abstract

Subsea jumpers connecting the underwater wellhead and nearby manifold commonly undergo flow-induced vibration (FIV) due to the spatially frequent alteration in the flow direction, velocity, pressure and phase volume fraction of the oil–gas two-phase flow, potentially leading to fatigue damage. This paper reports the numerical results of the FIV of a reversed U-shaped jumper excited by gas–liquid two-phase flow, which evolves from the initial slug flow with a fixed gas–liquid ratio of 1:2 when transporting through the jumper. The FIV response and flow pattern evolution are examined with a gas flow rate of Qg = 4–12 kg/s and a liquid flow rate of QL = 96–288 kg/s. When the gas–liquid flow passes through the jumper, the flow regime subsequently presents the slug flow, bubble flow, churn flow and imperfect annular flow. The out-of-plane response frequency coincides with the pressure fluctuation frequency for the four connecting bends, suggesting the fluid–structure interaction (FSI). Nevertheless, the vibration displacement is limited with the maximum value less than 0.0014D (where D is the jumper diameter) in the present considered flow rate range.