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© 2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary © 2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary
Engineering Simulation
Solutions for Offshore
and Subsea
Harish Radhakrishnan
ANSYS Inc.
© 2010 ANSYS, Inc. All rights reserved. 2 ANSYS, Inc. Proprietary
Oil and Gas Market Overview
Macro Drivers
• Shifting supply side – 687.44 billion barrels of oil (bbl) in proven reserves – Depleting sources of easily accessible oil especially
outside of Middle East. – Reserve degradation of the super majors – Rise of independents and national oil companies – Viability of unconventional resources
• Tar sand, oil shale and coal-to-liquid, ultra-deep sea • Increasing demand
– Not sustainable at 106mb/d usage projected by 2030 – Growing global demand for automotive
• Global capacity to refine crude is not expanding rapidly – Need for cleaner burning liquid fuel
• Role of natural gas – Natural gas to increase by 51% from 2005-2030 to 158
Trillion cubic feet – Electricity generation from Natural gas will increase to
5.5% and 4.6% respectively in China and India – Increase production and transport of liquefied natural gas
(LNG)
© 2010 ANSYS, Inc. All rights reserved. 3 ANSYS, Inc. Proprietary
Key Market Problems
Reliable and Safe Product and
Processes - Drilling and Production
• Inherently complex problems – Deep-waters, high pressures – Temperature variation – Hurricane, waves, – Dense areas, combustible and
hazardous products – Drilling through complex geology,
long distances – Many production and processing
equipment : Topside, subsea • Enormous cost
– Human life – Environmental concerns – Delays and fines – Loss of capital, time and equipment
© 2010 ANSYS, Inc. All rights reserved. 4 ANSYS, Inc. Proprietary
ANSYS Presence
Diverse Range of Applications
• Oil-Water-Gas Separators
• Anchor Chain Drag • Ball Valves • Boilers • Cage Valve Erosion • Cementing • Check and Chock Valves • Downhole Filter Erosion • Downhole Injectors • Drill Bit Cooling and
Cuttings Removal • Drill Bit Design • Drill Bit String and
Electronic • Fire Suppression
• Flare Stacks • Fluidized Catalytic
Cracker (FCC) • Furnaces • Gas Dispersion • Gas Lifts • Gas Processing • Gas Separation • Generators • Heat Exchangers • Horizontal Drilling
Hydrocyclones • Jet and Pool Fires • Leaks and Seals
• Logging While Drilling • Mud Drilling Fluid • Mud Sedimentation • Pipe Manifolds • Pumps • Radial Reactor • Smoke Accumulation • Storage Tank Collapse • Subsea Blow-out • Subsea Landslide • Subsea Oil Cooling Coils • Vortex Induced Vibration
© 2010 ANSYS, Inc. All rights reserved. 5 ANSYS, Inc. Proprietary © 2010 ANSYS, Inc. All rights reserved. 5 ANSYS, Inc. Proprietary
Example
Applications
© 2010 ANSYS, Inc. All rights reserved. 6 ANSYS, Inc. Proprietary
Global Assessment of Floaters
• Remaining new Oil & Gas fields largely offshore, and in ever deeper water
• One off designs • High capital investment • Failure consequences high • Extreme environmental
conditions – Ultra deep water – Hurricanes
• Difficult to physically prototype given the design requirements
© 2010 ANSYS, Inc. All rights reserved. 7 ANSYS, Inc. Proprietary
Global Assessment of Floaters
• Many considerations – Stability – Integrity of
mooring/tether systems – Dynamic positioning
(station keeping) – Fatigue of
moorings/risers – Wave slamming – VIM/VIV – Structural integrity – Human factors
© 2010 ANSYS, Inc. All rights reserved. 8 ANSYS, Inc. Proprietary
Complete Solutions
• The ANSYS solution provides tools for all aspects of offshore simulation – ANSYS CFD can be used to
provide input to ANSYS AQWA for viscous effects
– ANSYS CFD can also be used to examine specific design issues that require better physical modeling, such as wave slamming and ride-up, sloshing
– The interface to ANSYS Mechanical products provides a simple and accepted method for assessing structural adequacy of floating offshore vessels
© 2010 ANSYS, Inc. All rights reserved. 9 ANSYS, Inc. Proprietary
Drill Bit Analysis
© 2010 ANSYS, Inc. All rights reserved. 10 ANSYS, Inc. Proprietary
Cementing/Mudflow in Casings
Experimental cutaway of cementing in an eccentric gap used for validation of CAE simulation.
Velocity profile in an eccentric gap (left), contours of turbulent viscosity (right)
Some images courtesy of Halliburton
© 2010 ANSYS, Inc. All rights reserved. 11 ANSYS, Inc. Proprietary
Gas Dispersion
Some images courtesy of BMT
Some images courtesy of Kerr-McGee North Sea
© 2010 ANSYS, Inc. All rights reserved. 12 ANSYS, Inc. Proprietary
Flare Radiation
Flare flow pathlines,
coloured by
temperature
Flame shape and shroud surface
temperature for two different fuel
and wind ratios
Fuel to
Wind ratio
1:2
Fuel to
Wind ratio
2:1
© 2010 ANSYS, Inc. All rights reserved. 13 ANSYS, Inc. Proprietary
Wave\Wind Loading
Transient pressure distribution caused by ocean waves on an shallow water platform
Some images courtesy of BP
© 2010 ANSYS, Inc. All rights reserved. 14 ANSYS, Inc. Proprietary
Application Examples
Off-shore structures
Modal Analysis Harmonic Analysis Static Structural Analysis
© 2010 ANSYS, Inc. All rights reserved. 15 ANSYS, Inc. Proprietary
Blast Analysis
Simulated
stress on a
section of
LPG tanker
Façade
Detonation
Response
© 2010 ANSYS, Inc. All rights reserved. 16 ANSYS, Inc. Proprietary
Umbilical, Risers & Flexible
Piping
Equivalent stress response of the multi-
layer umbilical to a 36 degrees bend
© 2010 ANSYS, Inc. All rights reserved. 17 ANSYS, Inc. Proprietary
Application Examples
Thermo-Mechanical Analysis of
Umbilicals
© 2010 ANSYS, Inc. All rights reserved. 18 ANSYS, Inc. Proprietary
Tank Sloshing
Without baffles
Colored contours of
gas, oil and water
in a separation tank
Baffle stress With baffles
© 2010 ANSYS, Inc. All rights reserved. 19 ANSYS, Inc. Proprietary
Renewable Energy : Turbines
Vertical Axis
Marine Turbine
Axial turbine
Blade
stress
analysis
© 2010 ANSYS, Inc. All rights reserved. 20 ANSYS, Inc. Proprietary
Propulsion, Propeller Wakes & Cavitation
Courtesy SVA-Potsdam (Potsdam
Model Basin)
© 2010 ANSYS, Inc. All rights reserved. 21 ANSYS, Inc. Proprietary
Valves, Chocks, Regulators and Pumps
Flow streamline
for a petroleum
control valve
Subsea regulator
Surface temperature
on a valve surface
Some images courtesy of Hydril
Wellhead
Thermal
data
© 2010 ANSYS, Inc. All rights reserved. 22 ANSYS, Inc. Proprietary
Pressure Vessels
Stress, deformation
and fracture
© 2010 ANSYS, Inc. All rights reserved. 23 ANSYS, Inc. Proprietary
Global Design Solutions - Floaters
• ANSYS AQWA is primarily for global mooring performance, but does much more – Connect /offloading
/disconnect scenarios – Float-over installations – Launching installations – Lifting operations – Transportation – Failure conditions – Air gap – User definable functionality
© 2010 ANSYS, Inc. All rights reserved. 24 ANSYS, Inc. Proprietary
Ship & landing craft Jacket launch Lifting operation – AMOG
Truss spar – Technip Floatover Stinger
Hydrodynamic Modelling
© 2010 ANSYS, Inc. All rights reserved. 25 ANSYS, Inc. Proprietary
Shielding Mooring systems
FPSO & TLP Concept
Self-installing platform
– Arup Energy
Cargo lowered
onto vessel
Offloading operation – SBM
Hydrodynamic Modelling
© 2010 ANSYS, Inc. All rights reserved. 26 ANSYS, Inc. Proprietary
AQWA-FLUENT Coupling
15m string attached to top center of the cylinder
String draw down rate – 1 m/s
Cylinder mass – 5000kg
© 2010 ANSYS, Inc. All rights reserved. 27 ANSYS, Inc. Proprietary
Fully Coupled FLUENT-AQWA
• Automated coupling • FLUENT and AQWA exchange information at each time
step • Multiphase VOF model with Open Channel Boundary
Condition in FLUENT to include waves effects • Accurate and effective for these subsea applications
Transient FLUENT simulation with Rigid Body motion
AQWA simulation for Global Analysis
Drag forces/moments
Linear and angular velocities
© 2010 ANSYS, Inc. All rights reserved. 28 ANSYS, Inc. Proprietary
Animation
© 2010 ANSYS, Inc. All rights reserved. 29 ANSYS, Inc. Proprietary
Code Check
• ANSYS Heritage in Offshore Structural Analysis – ANSYS ASAS – system level analysis – ANSYS Mechanical – component level analysis
• Current ANSYS Offshore Structural Analysis – ANSYS Workbench – System & Component
• Design Modeler • ANSYS Structural • Splinter/Fatjack/Beamst • Links for coupled simulations
© 2010 ANSYS, Inc. All rights reserved. 30 ANSYS, Inc. Proprietary
ANSYS Mechanical Applications
• Offshore Structures • Pipelines and Risers • Tubulars, connectors • BOPs • Pressure vessels • Seals • Hulls • Etc….
Courtesy of Delta Marine Engineering Company Courtesy of ACA Engineering Consultants
© 2010 ANSYS, Inc. All rights reserved. 31 ANSYS, Inc. Proprietary
Design Assessment
- Introduction
• What is Design Assessment? – Enables the customer to define additional data that is associated with
their model and then perform custom post processing. • Custom definition of input data, result definitions & solve + post scripts
– Without any customisation, it enables the combination of existing solutions
• Static Structural • Flexible Dynamics (at a specific time)
– Predefined scripts for BEAMST and FATJACK.
© 2010 ANSYS, Inc. All rights reserved. 32 ANSYS, Inc. Proprietary
ANSYS Structural Mechanics
• ANSYS Structural analysis
© 2010 ANSYS, Inc. All rights reserved. 33 ANSYS, Inc. Proprietary
Offshore System level analysis
Requirement Oil & Gas fixed Jacket
Wind Turbine fixed Jacket
Oil & Gas Floating
Geometry DM/SCDM DM/SCDM DM/SCDM
Wave + Current (tubular)
ANSYS/Structural ANSYS/Structural
ANSYS/Structural
Wave + Current (shell/solid)
- - Via AQWA
Pile analysis Splinter Splinter -
Aeroelastic coupling
- ANSYS/Structural via shared DLL
-
Fatigue (tubular) FATJACK FATJACK FATJACK
Fatigue (shell/solid)
- - OSAP/nCode
ULS (tubular/beam)
BEAMST BEAMST BEAMST
ULS (shell/solid) - - OSAP
FSI - - -
© 2010 ANSYS, Inc. All rights reserved. 34 ANSYS, Inc. Proprietary
• Coupled hydro-elastic analysis for tubular framed structures – Fully coupled hydrodynamic loading with non-linear analysis capability – Automatic computation of hydrodynamic damping – Regular and irregular waves – Ability to take RAO results as time history loading – Tube-in-tube contact
Tubular Coupled Wave-Structures
• Wave loading for application of Morison forces (coupled for non-linear analyses)
• Calculation of added mass due to marine growth
• Hydrodynamic mass calculations • Buoyancy calculations, including
free flooding
© 2010 ANSYS, Inc. All rights reserved. 35 ANSYS, Inc. Proprietary
ANSYS - Code Checks (FATJACK/BEAMST)
• Joint Code & Member Code checks including: – AISC 10th edition working stress and 2nd edition LRFD – API RP2a-WSD 21st edition working stress – RP2A-LRFD 1st edition – ISO 19902
• Easy-to-use code check facilities including: – Code checks on time histories – Code checks on combined load cases – Visualization of code checks – Ability to use them in combination with ANSYS calculations
© 2010 ANSYS, Inc. All rights reserved. 36 ANSYS, Inc. Proprietary
• FATJACK module offers both deterministic and spectral fatigue capabilities – for tubular frame structures subjected to waves and current or wind including
wind gusts – can be used in frequency and time domain – sea states: JONSWAP, Pierson-Moskovitz, Ochi-Hubble, Scot-Weigel and
Shell New Wave, or user-defined wave spectra
• FATJACK includes explicit SCF definitions – SCFJ – if crown & saddle SCF is known e.g. from empirical formulae – SCFA – if SCF is known at specific locations e.g. from FE – SCFB – if SCF is constant across a section – SCFP – if SCF values vary with location
• Automatic (empirically derived) SCF definitions based on – Efthymiou, Wordsworth, Kuang or DS449
ANSYS
- Fatigue Assessments
© 2010 ANSYS, Inc. All rights reserved. 37 ANSYS, Inc. Proprietary
ANSYS
- Fatigue Assessments: Rainflow counting
• Reduces spectrum of varying stress into simple stress reversals • Allows the application of Miner’s rule to assess fatigue life of structure
subject to complex loading • Based on ASTM E1049-85 (2005) Standard Practices for Cycle Counting
in Fatigue Analysis • It is possible to use results from up to 1000 different transient dynamic
analyses and loading (i.e., multi-directional wave spectra) • Uses Rainflow counting method to produce stress range histogram • Results can be combined using a probabilistic approach, output includes:
• fatigue life (based on Miner´s rule) • usage factors • damage per wave (history) • stress histograms
© 2010 ANSYS, Inc. All rights reserved. 38 ANSYS, Inc. Proprietary
ULS Check in Design Assessment
© 2010 ANSYS, Inc. All rights reserved. 39 ANSYS, Inc. Proprietary
System to component analysis
• Detailed joint analysis is possible:
© 2010 ANSYS, Inc. All rights reserved. 40 ANSYS, Inc. Proprietary
Summary
• ANSYS continues to offer and invest in significant capabilities for offshore applications – Significant progress in implementing key features of
ASAS in ANSYS Structural Mechanics products – New Design Assessment tool enabling advanced
customized post-processing, including application of ANSYS developed code checking tools and user custom capabilities (not limited to Offshore)
– Separate code checking products
© 2010 ANSYS, Inc. All rights reserved. 41 ANSYS, Inc. Proprietary © 2010 ANSYS, Inc. All rights reserved. 41 ANSYS, Inc. Proprietary
Thank You
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