Session: 04-04-04: Rigid Pipelines IV

Submission Number: 156552

Advancements in Vortex-Induced Vibration Fatigue Prediction for Subsea Pipeline Free Spans: Research Progress From the TIDE Research Hub 

Free spans pose a major challenge when designing and maintaining subsea pipelines. These spans can form due to natural seabed irregularities, manmade irregularities (such as buckle initiator or crossing structures) and local scour. When ocean waves and currents interact with a free spanning pipeline section,  alternate vortex shedding may develop, potentially leading to vortex-induced vibration (VIV) and fatigue damage. The pipeline response, the ensuing amount of fatigue, and consequently whether the free-span requires mitigation, is governed by complex coupled interactions among the pipeline, seabed, and flow. Given the complexity of these interactions, predictions of VIV-induced fatigue based on design codes (such as DNV-RP-105) are necessarily simplified and are thereby likely to be conservative.

To investigate potential conservatisms in design practice, this research systematically considers several separate factors (such as hydrodynamics and the effect of near-seabed turbulence, local seabed irregularities, marine growth on spans, non-linear soil springs, etc.) and how these factors are combined to change the structural and fatigue behavior of a free-spanning pipeline. This research is being undertaken within the Transforming energy Infrastructure through Digital Engineering (TIDE) Research Rub (https://tide.edu.au/) at The University of Western Australia.  The team comprises academics, students and multiple industrial collaborators, with activities that include (1) reviewing pipeline survey data across multiple pipelines from installation to operation stages to identify changing free-span geometry, (2) conducting laboratory model tests and high-fidelity numerical simulations to investigate VIV, (3) analyzing span propagation due to local scour, and (4) studying bedform migration. The research aims to generate tailored design advice for individual components of the free-span system, that can be integrated into structural dynamic models to enable improved fatigue prediction – and this paper provides an overview of the current progress of the research program.

Presenting Author: Phil Watson The University of Western Australia

Presenting Author Biography: Phil is the Shell Professor of Offshore Engineering and Director of the ARC ITRH on Transforming energy Infrastructure through Digital Engineering (TIDE, https://tide.edu.au/) at University of Western Australia. He is a highly experienced offshore geotechnical engineer with over 25 years experience, and previously held the position of Global Director of GeoConsulting for Fugro. At Fugro he was a champion of innovation and technology development, working to integrate specialist consulting teams around the world, and with a commitment to sharing expertise and streamlining access to leading edge design approaches. Prior to joining Fugro, Phil was a Director of specialist geotechnical consulting firm Advanced Geomechanics, based in Perth.
Phil is a Fellow of The Australian Academy of Technology and Engineering, a Fellow of the Institution of Engineers Australia, the current Chair of ISSMGE Technical Committee 209 ‘Offshore Geotechnics’, and a committee member of ISO Working Group 10 / API Resource Group 7.