de-risking offshore installation of flexiblesand umbilicals ... vessel position (m) riser payout (m)...

www.xodusgroup.com

De-risking offshore installation of flexibles and umbilicals through the use of detailed global analysis modelling

Chris Jones

Global 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

Installation Analysis

Lay Tables

Procedure


Environmental Limits

Installation Analysis Software Programs

> OrcaFlex

> Flexcom / Pipelay

> Riflex / Simo

> Offpipe (Rigid Pipelay)


OrcaFlex www.orcina.com

Flexcomhttp://www.mcskenny.com/software-solutions/flexcom.html


“Typical” Analysis of a Flexible Flowline or Umbilical > 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

Riser Pull-In To FPSOExample

Riser LaydownExample

Riser Laydown – Lay TableExample

Step Vessel Position (m)

Riser Payout (m)

A&R Payout (m)

Tensioner Load (Tonnes)

A&R Wire Load (Tonnes)

Riser MinimumBend 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

The main part of the installation process often provides low risk to the product

> 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

> The devil is in the detail!

Experience from Installation Analysis

> An umbilical is stored on a reel or carousel on the back of the installation vessel

> The umbilical path from the carousel to the water during lay is usually controlled by a series of sheaves and chutes

> However to get the end fittings into the water, they need to be freely lifted – High risk to the product!!

Deck Handling and OverboardingExample

Deck HandlingExample

CarouselDeck

Tensioner

Overboarding Chute

Deck Deflector

Umbilical Path

Installation Vessel Aft Deck

Deck HandlingExample

Deck Handling – Dynamics – Pendulum EffectsExample

Double Pendulums

Deck Handling – Dynamics – Pendulum EffectsExample

> Limit the sea state if needed to ensure dynamic motion does not damage the product

> Limit Hs (amplitude) or Tp (avoid resonant periods)

> MRU Direct Crane Tip Measurement

> Irregular Waves

Pendulum Effect!

https://www.youtube.com/watch?v=ZD8y7Slx2ow

Deck Handling 2nd End From Carousel To Splash ZoneExample

Vertical Lay System – Lift End Fitting Over TowerExample

PLET LaydownExample

AnchorInitiation

Wire

PLET

PipelinePipelay Vessel

PLET

PLET Laydown – Detailed ModelExample

Detailed Model

> Yoke Swivel Model

> Accurate COF and COB

> Detailed Drag Coefficients and Added Mass Estimates

Observation – snatch loading in the initiation wire

PLET Laydown – Simplified ModelExample

Simplifed Model

> PLET modelled simply as a line

> No yoke – initiation wire connected direct to end of PLET element

> Drag and added mass not modelled In detail

> Submerged weight correct

Static configuration correct but poor dynamic analysis

PLET LaydownExample

In Summary….

Crane Block

Tri-Plate / Rigging / Lifting Tool

Buoyancy

End Fitting Bend

Restrictors

.

Reduced Risk

Higher Sea State

Better Definition

Installation Equipment

CoG

Buoyancy Rigging

Hydrodynamic Properties

Bend Restrictors/ Stiffener / Uraduct

www.xodusgroup.com

Thank you

All offshore images kindly supplied by Ocean Installer

de-risking offshore installation of flexiblesand umbilicals ... vessel position (m) riser payout (m)...

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