Session: 08-07-02 Internal Flows & FIV II

Paper Number: 80271

80271 - Lazy Wave Riser Slug Induced Vibration - Modelling Validation 

The paper addresses the flow-induced response of lazy wave riser system (either rigid or flexible). It mainly focuses on the mechanical response resulting from internal intermittent slug flows. The proposed works make echo to some previous papers (OMAE2020-18620, OMAE2021-60717), proposing novelty and additional features to be either considered in front end or detailed engineering. The focus will be done on the validation process of the proposed numerical models to assess the fatigue induced by such complex coupled physics.

The proposed method suggests coupling both multi-phase flow and mechanical solvers to recover the complex riser response. The coupling is ensured in both time / space to account for the variability of the slug flow properties along the riser. For validation purpose, a large-scale model test (19m long, 2’’ diameter) is proposed to (i) fully characterize the internal slug flow propagation in the lazy wav riser and then (ii) characterize the mechanical riser response. To feed the discussion on how to assess the total fatigue life and consider the different contributions, additional heave and vortex induced excitations are considered and compared.

The rough data coming from the large-scale model test have been firstly exhaustively post-processed to validate the expected internal flow regime against few existing well known empirical formulations. Then, they have been considered to characterize the slug flow at different locations in the riser system and to conclude on the variability of the slug flow properties along the riser system. On the same basis, the mechanical response (considering concomitant heave and current excitation) has been fully characterized and correlated to the different excitation sources.

Based on the exhaustive dataset, both flow assurance tools and the proposed coupled modelling has been experienced against the experimental data. An excellent match has been obtained considering the proposed modelling for a large range of flow conditions comparing the dynamic response of the riser. In the meantime, a simplified method has been also considered and validated for preliminary screening analysis.

The last part of the paper will open the discussion on the way to assess the riser overall fatigue considering different concomitant contributions such, as slug, VIV, Waves, to finally reduce the potential intrinsic conservatism of the current recommended practices.

Presenting Author: Matthieu Minguez SEAL Engineering (TechnipFMC subsidiary)

Authors:

Matthieu Minguez SEAL Engineering (TechnipFMC subsidiary)
Kevin Le Prin SEAL Engineering (TechnipFMC subsidiary)
Cristian Jara SEAL Engineering (TechnipFMC subsidiary)
Alain Liné TBI Université de Toulouse
Alexandre Cinello OCEANIDE
Thierry Rippol OCEANIDE