MCE Deepwater Development 2015Modularity of PLET and ILT design

for easy offshore installation and pipelay

March 24th 2015

Emmanuel Fontaine

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1- PLET and ILT functionalities2- Offshore installation methods3- Installation constraintsand impact on design4- Mudmat modularity5- Conclusions

Agenda

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1 - PLET AND ILT FUNCTIONALITIES• A PLET or ILT makes connection between the pipeline and a well or

manifold

• Contains special features:

- A piping bend with one connector or

more + valves and secondary featings

- A piping frame to hold the piping elements

and protect from dropped object

- A mudmat foundation to sustain:

Gravity load

Environmental loads

Equipment loads

Pipeline, Jumper loads

Mudmat can be sliding on seabed or allow the pipeline expansion (rails)

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2 - OFFSHORE INSTALLATION METHODS

• Requires to accomodate a range of installation methods

• Needs to cope with installation constraints

• Subsea Structure needs thus to be modular: Piping module; Mudmatmodule; Special double joint module

• Some part are standardized with specific dimensions for flexibility and variety in use (S-J-Reel)

Installation Vessels3 Installation

modesS-Reel-J lay

3 Types of structurePLET – First End

PLET - Second EndInline Tee (ILT)

Thus 9 Groups of design to cope with

vessels and structure types

FUNCTION

CLIENT NEEDS

PLET-ILT

DESIGN

VESSELTO

INSTALL

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2 - OFFSHORE INSTALLATION METHODS

Assemblyin S-lay

firing line

Double joint module

Piping module

Foundation module

StingerPLET in

Catenary(S-type)

Buoyancy module

S-LAY

J-laytower/weldingstation

PLET in Catenary(J-Type)

Buoyancy module

PLET handling system

Pipingmodule + double joint module + foundation J-LAY

PLET handling system

Pipingmodule + double joint module + foundation

Reel laywork

station/weldingstation

PLET in Catenary(J-type)

Buoyancy module

REELLAY

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2 - OFFSHORE INSTALLATION METHODS REEL-LAY INSTALLATION SEQUENCE

• PLET installed in Reel-lay • A PLET handling system (PHS) skids the structure aft and

transversally into the workstation for welding up to pipeline

Aligner Wheel

Pipe Storage drum

Lay rampat vessel Stern

PLET Handling SystemSeven Oceans

PLET in the workstation

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2 - OFFSHORE INSTALLATION METHODS REEL-LAY INSTALLATION SEQUENCE – Laydown case

Final landing of complete PLET or simple piping module on a Pre-installed foundation. Foundation could also be post-installed.

PLET

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2 - OFFSHORE INSTALLATION METHODS J-LAY INSTALLATION SEQUENCE – Laydown case

• PLET installed in J-lay

• Pipeline and structure are deployed along vessel side with a J-lay tower

J-lay tower

Seven Borealis

PLET

Pipeline catenary

J-lay tower structure

PLET handling frame

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2 - OFFSHORE INSTALLATION METHODSJ-LAY INSTALLATION SEQUENCE - Laydown

Last stage: Final Landing of the all integrated PLET or single pipingmodule on a Pre-installed foundation. The foundation can also be post-installed.

PLET up-righted

Buoys

Pipeline catenary

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2 - OFFSHORE INSTALLATION METHODS S-LAY INSTALLATION SEQUENCE – ILT CASE

For S-lay, the challenge is having the Piping module pass along the firing line: may be installed before/after tensioners

Joints are welded, Field joint coated Tensioners are opened to their maximum range

allowing the double joint module to transit

DOUBLE JOINTMODULE

PIPINGMODULE

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2 - OFFSHORE INSTALLATION METHODS S-LAY S-LAY INSTALLATION SEQUENCE – ILT CASE

• Then the structure exits the firing line and enter the stinger

• Cross of the overbend region• Buoyancy is connected• Exit the stinger and last

rollers• Last stage: Final Landing of

the complete ILT or single piping module on Pre-installed foundation. Mudmatcan also be Post-installed.

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2 - OFFSHORE INSTALLATION METHODS ALTERNATE DEPLOYMENT TABLE

• Use a deployment table (after pipeline recovery after a Reel J-S lay)

• Can be used for very large/heavy structure

• Not applicable for ILT• Requires recovery of the line

and installation of PLET in a second stage

• Can be done with a second vessel (without J/S or Reel capacity)

Hang-off table

Pipeline catenary

Abandonment cable

PLET

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3 - INSTALLATION CONSTRAINTS AND IMPACT ON DESIGN

• We have a wide range of installation constraints and Contractorneeds to integrate them in the PLET/ILT design.

• Need to specialize/adapt the design for each vessel tool.

• For foundation the greatest flexibiltity is coming with the Pre and Post-installed mudmat.

Pipi

ngm

odul

e •Similar for all 3 modes S, Reel, J

•But Requiresspecialinterfaces : the PLET handling toolsof Reel and J-lay towers Pi

pelin

e s

peci

aljo

int •Integrated to

piping module for Reel and J-lay

•Separated for S-lay

Foun

datio

nm

odul

e •Generallyintegrated (Reel/J)

•Can be separatedfor S-lay

•Can be Pre or Post installed for all 3 modes

•Can be fixed to piping module or allow it to slide ( with rails)

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3 - INSTALLATION CONSTRAINTS AND IMPACT ON DESIGN

With interface for J-lay handling With interface for Reel-lay handling

With separated pipingframe for S-lay handling

With special double joint (S-lay firing line)

PLET/ILT MODULE TYPES

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3 - INSTALLATION CONSTRAINTS AND IMPACT ON DESIGN

Mudmat integrated to PLET/ILT(w/o foldable wings)

Pre-installed mudmat

Suction Pile for stab and hinge over system Post-installed mudmat

PLET/ILT FOUNDATION

MODULE TYPES

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4 - MUDMAT MODULARITY• The structure overall size is a constraint for the offshore

deployment.• The mudmat can be quite large and heavy.• The weight of the PLET is increased due to the mudmat (+ 10-

20 MT).• Additional buoyancy is required for the mudmat.• The mudmat is adding a hydrodynamic mass (limit sea states).• The installation time is increased as well as risks to deploy

heavy and large structure.• Solutions :Post-install the foundation on a pre-installed piping module

(patent pending)Pre-install the foundation and land the piping module inside

(patent pending)

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4 - MUDMAT MODULARITYPOST-INSTALLED MUDMAT SOLUTION

• Video of installation stages: the piping module exits the stinger, goes in the sagbend transit and lands on seabed, Mudmat is then connected by the top (patent pending)

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4- MUDMAT MODULARITYPRE-INSTALLED MUDMAT SOLUTION

Piping module and frame

Mudmat

Piping module and frame

Mudmat module

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4- MUDMAT MODULARITYGAINS WITH A MODULAR MUDMAT APPROACH

Geotechnic Pipeline Structure InstallationPost-installed:Mudmat is connected by the top Final settlement of the assembly is enabledby load transfer of piping module on the mudmat

Pre-installed:Mudmat is pre-installed on seabedMudmat settlementoccurs with selfweightof foundation, and further after pipingmodule landing

Both: No size limit to cope with very soft soil

Both:Can be used withS/Reel/J lay modes

Residual plastic strain (S & Reel lay) may induce a pipeline axial rotationBuoys counter the rotation and residual torsion to remain small for mudmatconnection (post-installed case) or piping module tilt (pre-installed case)

Less buoyancyrequired in catenary

Both:There is no size limitation for the mudmat

The piping frame can be sliding on mudmatand accommodate large thermal expansion

Installation is reversible: recovery is possible without overstressing the piping frame

Conception ismodular and can bestandardized

Post-installed:No need to oversize the mudmat for installation tolerances

Pre-installed:Mudmat size needs to account for installation tolerances +/-5m

Both: installedseparately and can bewith a smaller vessel

Lighter and safer to handle with vesselcranes

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5 - CONCLUSIONS

• S-Reel-J methods require specific interfaces on PLET/ILT modules for installation.

• Design must take into account these constraints (in pipingand mudmat module) by having common part related to installation method.

• Thinking modular ease the design and installation• The Pre or Post-Installed mudmat modules offers great

flexibility for installation • The Pre and Post-Installed mudmat design are applicable to

S, J or Reel-lay• A separate foundation module allow lighter structure in the

firing line (the structure is easier to handle)

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• Thank you for your attention

• Any Questions ?

• Emailemmanuel.fontaine@subsea7.com

This presentation only reflects the opinion of its author and does not imply endorsement by the company to which acknowledgements are made.

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