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De-risking offshore installation of flexibles and umbilicals through the use of
detailed global analysis modelling
Chris Jones
www.xodusgroup.com
Installation Analysis
Global Analysis
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Installation
Analysis
Using FEA software to model the
different stages of the installation of
a subsea product
Static and Dynamic Behavior e.g.
– Tension in the winch
– Tension in the
pipeline/flexible/umbilical
– Bending / Moments /
Curvatures
Lay Tables
Environmental
Limits
Procedure
Installation Analysis
Installation Analysis Software
Programs
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OrcaFlex
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Flexcom / Pipelay
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Riflex / Simo
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Offpipe (Rigid Pipelay)
OrcaFlex www.orcina.com
Flexcom
http://www.mcskenny.com/software-solutions/flexcom.html
Installation Analysis
“Typical” Analysis of a Flexible Flowline or Umbilical
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Lowering to the seabed
Land the 1st End Termination
Normal pipelay
Lower the 2nd End
Land the 2nd End
Also
> J-Tube Pull-Ins
> Riser Pull-In (e.g. pull in to FPSO)
> etc
Example
Riser Pull-In To FPSO
Example
Riser Laydown
Example
Riser Laydown – Lay Table
Step
Vessel Position Riser Payout
(m)
(m)
A&R Payout
Tensioner
A&R Wire Load
(m)
Load (Tonnes)
(Tonnes)
Riser Minimum
Bend Radius
(m)
1
175
355
-
24.6
-
32
2
275
650
-
44.5
-
50
3
400
900
-
12.8
-
62
4
540
1200
-
37.2
-
48
5
570
1400
-
59.5
-
42
6
610
(1400)
250
-
74
45
7
620
(1400)
425
-
75
42
8
760
(1400)
575
-
60
33
9
890
(1400)
740
-
42
18
Experience from Installation Analysis
The main part of the installation process often provides low risk to the product
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Installation operations with the product in the water are often relatively
straightforward e.g. lowering and laying the product
Large MBRs
Wide range of payout and vessel position possible without damaging the product
Good safety margin
Higher risk is during deck handling, initiation, landing and tie-in operations
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The devil is in the detail!
Example
Deck Handling and Overboarding
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An umbilical is stored on a reel or
carousel on the back of the
installation vessel
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The umbilical path from the
carousel to the water during lay is
usually controlled by a series of
sheaves and chutes
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However to get the end fittings
into the water, they need to be
freely lifted
– High risk to the product!!
Example
Deck Handling
Overboarding
Chute
Carousel
Deck
Deflector
Deck
Tensioner
Umbilical
Path
Installation Vessel Aft Deck
Example
Deck Handling
Example
Deck Handling
Example
Deck Handling
Example
Deck Handling
Example
Deck Handling
Example
Deck Handling
Example
Deck Handling
Example
Deck Handling
Example
Deck Handling
Example
Deck Handling – Dynamics – Pendulum Effects
Double Pendulums
Example
Deck Handling – Dynamics – Pendulum Effects
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Limit the sea state if
needed to ensure
dynamic motion does
not damage the product
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Limit Hs (amplitude) or
Tp (avoid resonant
periods)
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MRU Direct Crane Tip
Measurement
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Irregular Waves
Pendulum Effect!
https://www.youtube.com/watch?v=ZD8y7Slx2ow
Example
Deck Handling 2nd End From Carousel To Splash Zone
Example
Vertical Lay System – Lift End Fitting Over Tower
Example
PLET Laydown
Anchor
Initiation
Wire
Pipelay
Vessel
Pipeline
PLET
PLET
Example
PLET Laydown – Detailed Model
Detailed Model
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Yoke Swivel Model
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Accurate COF and COB
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Detailed Drag Coefficients
and Added Mass Estimates
Observation – snatch loading in the
initiation wire
Example
PLET Laydown – Simplified Model
Simplifed Model
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PLET modelled simply as a line
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No yoke – initiation wire
connected direct to end of
PLET element
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Drag and added mass not
modelled In detail
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Submerged weight correct
Static configuration correct but
poor dynamic analysis
Example
PLET Laydown
In Summary….
Buoyancy
Rigging
Crane Block
Hydrodynamic
Properties
CoG
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Better
Definition
Installation
Equipment
Tri-Plate /
Rigging /
Lifting Tool
Bend
Restrictors/
Stiffener /
Uraduct
End
Fitting
Reduced
Risk
Higher
Sea State
Buoyancy
Bend
Restrictors
Thank you
All offshore images kindly supplied by Ocean Installer
www.xodusgroup.com