DNV GL © 2013 Revised: 11 May, 2014 SAFER, SMARTER, GREENERDNV GL © 2013
Fan Joe Zhang
Product Manager – SURF & Marine Operation, Design & Engineering
DNV GL - Software
DNV GL Teck Talk webinar:
Subsea manifold installation – go through the splash zone
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DNV GL © 2013 Revised: 11 May, 2014
Agenda
Introduction to Sesam Marine software: the software tool to be used in the presentation and demo
Introduction to the subjects
Body(ies) definition and objects
Couplings
Conditions
Post- processing
Typical applications and examples
Demo
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Introduction to Sesam Marine
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Common challenges in marine operations engineering
How do you compute the sling forces?
how do you know contact forces?
How do you know what to do when something unplanned happens?
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DNV GL © 2013 Revised: 11 May, 2014
Sesam Marine
Managing risk of marine operations with visual simulation of calculations
Sesam Marine
Managing risk of marine operations with visual simulation of calculations
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DNV GL © 2013 Revised: 11 May, 2014
What is Sesam Marine?
A complete package for simulation of marine operations, from modelling to results
Build upon “state of the art” software for dynamic analysis
Graphical user interface makes modelling fast and easy
Developed together with Marintek
– Includes the modules named Sima, Simo and Riflex.
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DNV GL © 2013 Revised: 11 May, 2014
Marine operation analysis workflow in Sesam software
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Sesam GeniE Sesam HydroD
Panel and other models to run hydrodynamic analysis
DATA
Added mass, damping coefficients, 1st and 2nd
order wave loads, etc.
Sesam Marine
Graphicfiles
Graphic files for animation
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What Sesam Marine can be used for?
Engineering
– Quality assurance
– Feasibility evaluation
– Distinguish the really challenging tasks from the seemingly challenging tasks
Preparation for the actual operation
– Improve HSE performance
– Familiarization
– Cross – disciplinary communication
Decision support during actual operation:
– Online monitoring
– Visibility
– What – if – analysis
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Simulating boarding
Simulating pipelaying
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Introduction to the subjects
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The following subjects will be presented
Calculation of motion of any number of bodies– Weak positioning and coupling forces– Integration of equations of motion for each body separately– Maximum time step related to lowest natural period
Each body has 3 or 6 degrees of freedom (DOFs)– Various force models
Positioning system– Springs– Mooring lines– Thrusters
Couplings– Springs and dampers:
– Lines, winches– Fenders, bumpers– Docking cones
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System Modelling: GUI
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Basic definitions and objects– Location and environment– Body(ies) definition– Couplings– Calculation parameters– Conditions
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Location and environment definition
Location
– Physical constants
– Acc. of gravity
– Water density
– Air density
– Water depth
– Etc.
– Sea surface and flat bottom
Environment
– Wave
– Swell
– Wind
– Current
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Body(ies) definition
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Definition of bodies – 4 types
1. Large volume body, 6 degrees of freedom. Total motion is simulated in time domain
2. Large volume body, 6 degrees of freedom. Separation of motion calculation:
– First order wave motion calculated in frequency domain, from motion transfer functions.
– Low-frequency motion calculated in the time domain
3. Small volume body, 3 translation degrees of freedom. Position dependent hydrodynamic coefficients are allowed
4. Immovable body. Used for control and study of dynamic forces on a body, without the influence from body motion
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Parameters for bodies
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Read from hydrodynamic analysis
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Time dependent mass
Useful for ballasting during heavy lift operations
– offshore mating
– module removal
Options
– Specified mass change rate at given position
– Filling of tank with simple geometry, specify flow rate, effect of slack tanks
Applications
– Simulate a ballasting sequence and its influence on the static and dynamic response of a vessel.
– Model a sudden or gradual waterfilling of a subsea module after a specified time.
– The specified increase or decrease in mass both affect the gravity force and the mass matrix.
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0
100
200
300
400
500
600
. .. ... Time
Mas
s (t
)
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Positioning system
Various optional systems used control the global position of a body, such as:
Thrusters, either controlled by a DP system or not
Catenary mooring lines
Linear or non-linear springs connecting the body to a globally fixed point
Various guiding or contact element types
The springs and contact elements can also be used for coupling elements between bodies.
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Simplified Lift Line Model
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A fast and accurate lift line model for prediction of total static and dynamic line end forces and load offset.
Validation with irregular waves: Hs = 4m, Tz = 5s
Water depth: 3000 m
Load mass: 30 t
Added mass: 10 t
Wire mass: 30 t RIFLEXSIMO
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Couplings– Connection and contact element models– Hydrodynamic couplings
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Docking cone
Docking cone model can be used both as a global positioning element and a coupling element between bodies
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OBJ1
Δz
Δz1 Δz2
Force
Radial distance
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Fender
The fender model can be used both as a positioning element and as a coupling element, and expresses the contact force between a fender (point or cylinder) and a plane.
The following characterizes the fender model:
– Zero contact force for distances larger than a specified value
– Compression force normal to the plane calculated from a specified deformation - force relation
– In-plane friction proportional to the normal force (static and dynamic friction may be different). Shear stiffness and deformation of the fender included.
– The plane can have any position and orientation
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Fenderpoint
Fender element w/ rolling
Fender point
Fender element w/o rolling
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Fender examples
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Roller berthing fender at ship's side Roller fenders between two ships
Spherical fender Fenders used as support membersFender used for dist. measurement
Fixed berthing fender at ship side
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Bumper
The bumper element model is used to model contact force between a body and a globally fixed cursor or bumper, or contact forces between bodies:
Particularly useful in the analysis of offshore installation operations, where deflectors / bumper bars are used to guide a module to its correct position and to protect existing equipment from impact damages.
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Bumpers
Cone/support
1
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The final control of horizontal position can be accomplished by docking cones, and the vertical supports by linear springs.
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Topside docking cone with bumper
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Fenders and connecting wires
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Hydrodynamic coupling
Most accurate method is to include full hydrodynamic coupling as well as mechanical coupling between the two vessels.
Hydrodynamic coupling between the vessels includes
– Coupled added mass
– Coupled retardation functions
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Calculation Parameters
In a SIMO or RIFLEX task there are static and dynamic calculation parameters that must be adjusted to suit the needs for the given project.
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Conditions– Initial condition– Condition– Condition set– Conditions space
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Conditions and analysis
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Condition set and condition space
Condition set is used to define a list of runs (i.e. a parameter variation) based on variables defined in the task.
– One or more variables as fixed for all runs in the "Configure fixed variables" section
– User may also set one of the variables as a probability variable -typically used for fatigue analyses. The probability variable must add up to 1 for all simulation runs combined.
Condition space is used to create a matrix of runs based on variables defined in the task.
– All variable values are run against each other.
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Flexibility
Easy to modify parameters and to run several simulations
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Post-processing
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Direct plotting from result data - “Fast results”
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Post-processing – Transparent (QC/QA)
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Diagram Palette
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Animation
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Typical Applications and examples
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Typical applications – Complex marine operations
Lifting of topsides and modules
Lifting and installation of SURF structures (templates, pipelines, flexible risers)
Float-over installation/removal of topsides
Load-out from quay to barge
Offloading (tankers in tandem or side-by-side)
Offshore crane operations
Jacket lift installation and removal
Transportation of offshore floaters (e.g. TLP, Semi, Spar)
Up-ending of SPAR
Towing by tugs (e.g. GBS)
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Marine operations at Sheringham Shoal
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Lifting of topsides and modules
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Jacket superstructure installation
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Dynamic analysis of a float-over operation
Jacket support: Docking cone
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Pendulum installation method
Developed by Petrobras Depth 3000m Template weight: 285t
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[m]
[s][s]
[kN
]
Tension at anchor handling vesselVertical template position
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Example: Installation of an 28" spool on the Snøhvit field
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Installed successfully by Technip Offshore Norge AS August 24, 2005
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Example: Installation of the Fram module onto TROLL C
The model includes:
Hydrodynamic models of TROLL C and S-7000
Dynamic positioning
Bumpers
Docking cones
Support elements
Crane wires
Tugger lines
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Example: Installation of a 500t module on Snorre A
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Multiple bodies
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Example: Field Bottom Structure for Ormen Lange (1050 t)
The model includes:
Hydrodynamic vessel model
Dynamic positioning
Fenders
Mooring hawsers
Support elements
Complete lifting configuration
Splash zone forces
Geotechnical forces
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Example: Installation of Ormen Lange Template
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1140 T TemplateInstalled on 850 m water depthby Heerema Marine Contractors 20.08.2005
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Example: Scandi Acergy installing Gjoa template
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Example: Ormen Lange - Inline Tee installation Use of local guidewires & guideposts
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Guide funnel with multiple guide point passages
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Exploring new installation methods
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Leg Turbine Platform Analysis – Feasibility study
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Demo case
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Installation of subsea structures
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RAOs
Vessel
DP
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Float-over installation
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4 fender couplings – bt1, bt2, bt3 and bt4Fenders Docking cone
Catenary mooring lineFixed force elongation
Bumper element
DNV GL © 2013 Revised: 11 May, 2014
SAFER, SMARTER, GREENER
www.dnvgl.com/software
Thank you!
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