Conference proceeding
Subsea Cable Stability on Rocky Seabeds: Comparison of Field Observations Against Conventional and Novel Design Methods
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering (OMAE), Vol.5: Pipelines, Risers and subsea systems, p.V005T04A043/1
ASME 2018: 37th International Conference on Ocean, Offshore and Arctic Engineering, Madrid, Spain, Jun. 17 - 22, 2018, Code 140007 (Madrid, Spain, 17/07/2018 - 22/07/2018)
25/09/2018
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Abstract
As offshore renewable energy projects progress from concept demonstration to commercial-scale developments there is a need for improved approaches beyond conventional cable engineering design methods that have evolved from larger diameter pipelines for the oil and gas industry. New approaches are needed to capture the relevant physics for small diameter cables on rocky seabeds to reduce the costs and risks of power transmission and increase operational reliability.
This paper reports on subsea cables that MeyGen installed for Phase 1a of the Pentland Firth Inner Sound tidal stream energy project. These cables are located on rocky seabeds in an area where severe metocean conditions occur. ROV field observation of these cables shows them to be stable on the seabed with little or no movement occurring over almost all of the cable routes, despite conventional engineering methods predicting significant dynamic movement.
We cite recent research undertaken by the University of Western Australia (UWA) to more accurately assess the hydrodynamic forces and geotechnical interaction of cables on rocky seabeds. We quantify the conformity between the cables and the undulating rocky seabed, and the distributions of cable-seabed contact and spanning via simulations of the centimetric-scale seabed bathymetry. This analysis leads to calculated profiles of lift, drag and seabed friction along the cable, which show that all of these load and reaction components are modelled in an over-conservative way by conventional pipeline engineering techniques. Overall, our analysis highlights that current cable stability design can be unnecessarily conservative on rocky seabeds. Our work foreshadows a new design approach that offers more efficient cable design to reduce project capex and enhance through-life integrity management.
Details
- Title
- Subsea Cable Stability on Rocky Seabeds: Comparison of Field Observations Against Conventional and Novel Design Methods
- Creators
- Terry Griffiths - University of Western AustraliaScott Draper - University of Western AustraliaLiang Cheng - University of Western AustraliaFeifei Tong - University of Western AustraliaAntonino Fogliani - University of Western AustraliaDavid White - University of SouthamptonFraser Johnson - MeyGen, Edinburgh, UKDaniel Coles - MeyGen, Edinburgh, UKStephen Ingham - JDR Cable Systems, Ltd., Hartlepool, UKCaroline Lourie - JDR Cable Systems, Ltd., Hartlepool, UK
- Publication Details
- Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering (OMAE), Vol.5: Pipelines, Risers and subsea systems, p.V005T04A043/1
- Conference
- ASME 2018: 37th International Conference on Ocean, Offshore and Arctic Engineering, Madrid, Spain, Jun. 17 - 22, 2018, Code 140007 (Madrid, Spain, 17/07/2018 - 22/07/2018)
- Publisher
- American Society of Mechanical Engineers; United States
- Identifiers
- 991013041311102368
- Academic Unit
- Faculty of Science and Engineering
- Language
- English
- Resource Type
- Conference proceeding