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

Installation Analysis

Environmental Limits

Installation Analysis Software Programs

> OrcaFlex

> Flexcom / Pipelay

> Riflex / Simo

> Offpipe (Rigid Pipelay)

Installation Analysis

OrcaFlex www.orcina.com

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

Installation Analysis

“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 HandlingExample

Deck HandlingExample

Deck HandlingExample

Deck HandlingExample

Deck HandlingExample

Deck HandlingExample

Deck HandlingExample

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