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Norsk Marinteknisk Forskningsinstitutt
PEMEX‐INTSOKDeepwater Technology Seminar
Cuidad del Carmen, May 9‐10, 2013
By Petter Andreas Berthelsen
MARINTEK USA Inc
Motion and responses for deepwater production systems
Introduction
Exploration of oil and gas in deeper water in areas where the weather conditions are extreme gives several challenges that need to be solved, e.g.:
• Wave‐current interaction• Extreme waves; higher order and viscous drift forces• Large mooring line forces• Green water and wave impact• VIV
• MARINTEK has long traditions with developing methods, carrying out analyses and verification with model tests of marine structures in deep water.
About MARINTEK
MARINTEK is a contract research institute within marine technology.
MARINTEK carries out contract R&D for marine related industries:• Maritime• Oil and Gas• Ocean Energy
Main Research areas are:• Hydrodynamics and structures• Energy and machinery technology• Operations technology
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MARINTEKNorwegian Marine Technology Research Institute
Main office in Trondheim, NorwayOffices in Oslo and BergenSubsidiary in Houston; MARINTEK (USA), Inc.Subsidiary in Rio de Janeiro; MARINTEK do Brasil, Ltda.
Marine Technology Centre, Trondheim
Rio de Janeiro
MARINTEK do Brasil, Ltda.
Houston
MARINTEK (USA), Inc.
Trondheim
OsloBergen
Ocean Basin Laboratory (80x50x10 m)
MARINTEK operates national marine technology laboratories
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Model tests in the Ocean Basin
Ocean Basin model test
Typical test set‐up:•Measurement of:
− 6 DoF motions by use of optical position meas. system
− Mooring line and riser forces− Relative wave elevation close to structure− Impact loads
•Observation (by video):− Green water− Motions of mooring lines and risers (by
underwater video)
Challenge:Deepwater system design verification by model tests
Ocean Basin 10m deepModel scale 1:150
Example: FPSO 3000 m water depth
Hydrodynamic loads not directly influenced by mooring/riser system
Can truncate mooring/risersto obtain hydrodynamic characteristics of floater
Truncation of mooring and riser system
• Truncated system should maintain the same hydrodynamic characteristics of the floater as the full depth system
• It is required that the responses measured with the truncated system can be reproduced by a coupled simulation model
− This numerical model will be used to obtain design values for the full depth system
=> Hybrid verification procedure
Hybrid verification procedure
Full depth and truncated mooring systems (VERIDEEP)
Quasi‐static characteristics comparison
Restoring force and single line Surge vs pitch
Comparison of dynamic line forces (VERIDEEP)Reduced depth Full depth
An active hybrid decomposed mooring system (HydeMoor) for model testing of deepwater offshore platforms
To be presented at OMAE2013, Nantes, France
From laboratories to numerical simulation tools
MARINTEK analysis tools
• SIMO – Simulation of rigid multibody system
• RIFLEX – Global analysis of risers, mooring, umbilicals
• MIMOSA – Mooring analysis
• SIMLA – Simulation of Pipe laying
• BFLEX – Local analysis of flexible risers• UFLEX – Local analysis of complex risers
• MULDIF 2 – Next generation potential flow solver
• SIMA – Graphical user interface
Example: Disconnected turret buoy system
• Coupled time domain analysis− Turret buoy 6DOF rigid body− Riser: FEM with pipe‐in‐pipe inside bellmouth− Umbilicial: FEM
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Example: Disconnected turret buoy system
Visualization: SimVis
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Example: Hybrid Risers/Disconnectable Turret/FPSO System
Visualization: SimVis
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Example: Hybrid Risers/Disconnectable Turret/FPSO System
Visualization: SimVis
Example: Turret Disconnection
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Visualization: SimVis
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Wave current interactions: Mooring line forces
6800 kN
4500 kN
Difference is larger than the line force from the current alone
Wave current interactions: Air gap
Increased wave amplification around semi columns with current present (MULDIF‐1, Zhang et al., 2007)
MULDIF‐2 Development
• Internal development at MARINTEK throughout 5 years
• Industry code implementation performed as a JIP− Present participants: Statoil, Aker Solutions, NOV‐APL, Rolls‐Royce Marine, DNV, MARINTEK
• Overall objective to develop a hydrodynamic potential theory code that handles various problems not handled well by excisting industry codes
− Effect from wave‐current interaction− Significant wave drift forces => large mooring and thrust forces− Airgap (increased wave amplification)
− It needs to be user friendly, robust and well validated
• Phase 1 (2010‐2013)− Focus on wave‐current interactions for single problems in deep and finite water depths
• Phase 2 (2013‐2015 plans)− Focus on semi‐empirical practical nonlinear corrections for higher sea states and for viscous effects − Multibody with current
SIMA – MARINTEK Workbench
• Developed in a JIP between MARINTEK and Statoil ASA. • The main simulation programs presently available through the SIMA interface are:
− SIMO− RIFLEX− SIMO/RIFLEX coupled analysis
• Future support− SIMLA− MULDIF2
• Purpose:− Make the task of setting up a
simulation model of a dynamic system easier and faster.
− Visualize everything− Workbench that presents the user
with a common interface no matter which simulation software is used.
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Thank you!
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COUPLED ANALYSIS APPROACH
• Time domain finite element model (e.g. RIFLEX‐C: SIMO + RIFLEX)
All interaction effects between mooring/risers and vessel are modelled directly
WIND
WAVES
CURRENT