HMPE lines in deepwater MODU mooring offshore Brazil · HMPE lines in deepwater MODU mooring...

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HMPE lines in deepwater MODUmooring offshore BrazilFaster relocations, reliable performance and survival

Sérgio Leite – Lankhorst Ropes – PortugalJorn Boesten – DSM Dyneema – Netherlands

Tuesday, 4th October 2011OTC Brasil 2011 – Rio de Janeiro

OTC 22486 · HMPE mooring lines · S Leite, J Boesten · 2/(20)

Agenda

• Why

• Drivers adoption HMPE in temporary platformmooring

• Properties rope with HMPE

• Case – system performance and storm stiffness

• Case – creep

• Operational benefits and cost savings

• Conclusions

Why HMPE offshore Brazil

• Need to efficiently drillhundreds of wells

• Deeper water depths

• 2-300 kilometersoffshore, logisticalchallenges

• Rising costs ofdeepwater MODUmoorings

Why HMPEFaster mooring operational cost savings

Cost factor Potential savingsCost factor Potential savings

Anchor handlingvessels

Use smaller ones

Less trips to shore

Use less time (fasterinstallation)

Installation &decommissioningtime

Faster using HMPE versuspolyester

(up to 40% faster)

Rig down time Faster hookup(twice as fast)

Connecting hardware Smaller (or no) buoys

Watch circle Smaller

MODU rope with HMPEConstruction and material

Construction: Gama 98

• Core: 12 Braided sub-ropes(laid parallel) from SK78 byDSM Dyneema

• Jacket: Overbraidusually Polyester, can be othersynthetic material

• Filter:Between core and the jacketrestricts the ingress of particles

MODU rope with HMPEProperties (with PET jacket)

General CharacteristicsStrength wet/dry 100 %Specific gravity ~1.04 (buoyant)Elongation Very LowWater absorption NoneAbrasion Resistance ExcellentMelting Point 140 oC HMPE

260 oC PET

Chemical Resistance (Jacket)Acids GoodAlkalis ModerateOil/Gas Very Good

Ultra Violet Resistance Excellent

MODU rope with HMPELoad extension properties

• Extension at break of 2%

• Similar to steel wire rope

• 3-4 times less thanPolyester

HMPE – PET mooring evaluationDelmar study

• Comparative study investigating performance ofHMPE, PET and hybrid moorings

• API RP 95F 2006 metocean conditions

51372mSK78

6915mChain

Typical mooring line

(2286 m WD)

Rig wire 610m 1,2

PET 915m 4

MODU rope with HMPE3-4 times stiffer than Polyester

• 3-4 times stifferthan Polyester

• Up to 50%reduction onwatch circle

Typical EA Values (*MBL) for rope with PET or HMPE

Stiffness Mode Polyester EA SK78 EA

Drift 15 60

Storm 30 105

Intact System Performance Curves

7500' water depth

0 200 400

Horizontal Tension (kips)

Polyester

Hybrid

Catenary

Steel Semi-Taut

Intact System Performance Curves

7500' water depth

0 200 400

Horizontal Tension (kips)

Polyester

Hybrid

Catenary

Steel Semi-Taut

Intact system performance curves2268 m water depth

Case - storm stiffnessGOM - MODU mooring reliability - API 95F 2006

• An HMPE MODU mooring system can be engineered tohave similar performance and survivability as a PETsystem in deepwater applications– with the benefit of improved station keeping

– also under the updated (more severe / post Katrina) APIstorm conditions in the GOM

– Hybrid configuration allows the system designer the ability toengineer system stiffness to optimize FOS and station keeping

HMPE – Technical challenge: creepCreep case study

• All HMPE fibers will creep under permanent load

• SK78 (low creep grade) is the only HMPE fiberapproved by Bureau Veritas and ABS for MODUmoorings

1,2610mRig wire

51372mSK78

6915mChain

Typical mooring line

(2286 m WD)

Buoy - 3

PET 915m 4

HMPE – Technical challenge: creepCreep case study – less than 0,1% line elongation in one year

• All HMPE fibers will creep under permanent load

• SK78 (low creep grade) is the only HMPE fiberapproved by Bureau Veritas and ABS for MODUmoorings

Calculated creep (m)

(3812m line length)

1 year 1.4

5 years 5.5 – 9.8

HMPE MODU rope compared to PET3x lighter and transport volume reduced by 40%

• 630t MBL rope, 1200 m

• Reduction on the reeldimensions – from Ø 4.0 mflange (Polyester) down to Ø 3.0m flange (HMPE)

• Rope weight decreases from 19tto 7t

Why HMPEFaster mooring operational cost savings

Cost factor Potential savingsCost factor Potential savings

Anchor handlingvessels

Use smaller ones

Less trips to shore

Use less time (fasterinstallation)

Installation &decommissioningtime

Faster using HMPE versuspolyester

(up to 40% faster)

Rig down time Faster hookup(twice as fast)

Connecting hardware Smaller (or no) buoys

Watch circle Smaller

HMPE in temporary platform mooringDrivers for adoption of HMPE versus PET

• Reduced operational costs when relocating drilling rigs

• Improved station keeping Enabling for moorings in water >2500meter deep

• Special grade developed for optimum performance in MODUmooring: Dyneema® SK78

Reliability

• Approved by Bureau Veritas and ABS for MODU moorings

• Use of rope with Dyneema® accepted by major operators such asShell and Petrobras

• Mooring analysis shows sometimes a polyester insert is needed forreduction of peak (storm) loads

ABS ApprovedABS ApprovedABS ApprovedABS Approved

Operational savings versus polyesterSystem cost evaluations

Higher Capex cost of a MODU mooring system withHMPE is offset by Opex savings with every rigrelocation

0 5 10

Relocations

Dyneema®

Conclusions

• Lankhorst ropes and DSM Dyneema have over 10 yearsexperience in supplying synthetics to offshore industry

• Gama 98® rope with SK78 from DSM Dyneema is aproven mooring line for deepwater moorings,accepted by major operators such as Petrobras

• Hybrid HMPE-PET mooring line design allows mooringengineer to optimize between station keeping andstorm survivability

• Higher initial CAPEX will be offset by OPEX savingsthrough ie faster installation and hook up

Sérgio Leite – Lankhorst Ropes/Offshore Division – Portugalsleite@lankhorstropes.pt

Jorn Boesten – DSM Dyneema – Netherlandsjorn.boesten@dsm.com

Obrigado – Thank you

HMPE lines in deepwater MODU mooring offshore Brazil · HMPE lines in deepwater MODU mooring...

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