Aasta Hansteen â the worlds largest SPAR
Aasta Hansteen â the worlds largest SPAR
Aasta Hansteen â the worlds largest SPAR
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<strong>Aasta</strong> <strong>Hansteen</strong> –<br />
<strong>the</strong> <strong>worlds</strong> <strong>largest</strong> <strong>SPAR</strong><br />
Øystein Gabrielsen, leading engineer - mooring<br />
2012-09-26
<strong>Aasta</strong> <strong>Hansteen</strong><br />
1824 - 1908 2016 →<br />
2<br />
2012-09-26
<strong>Aasta</strong> <strong>Hansteen</strong> – breaking barriers<br />
• Largest displacement<br />
• Widest<br />
• Largest topside capacity<br />
• No VIM strakes<br />
• With condensate storage<br />
• Offloading to shuttle tankers<br />
• Norhternmost <strong>SPAR</strong><br />
• Cut resistant fiber ropes<br />
• Steel Catenary Risers<br />
Water depth: 1300 m<br />
• (Not <strong>the</strong> deepest)<br />
3<br />
2012-09-26
<strong>Aasta</strong> <strong>Hansteen</strong> Mooring system<br />
Todays presentation:<br />
• Mooring Requirements<br />
• Mooring layout<br />
• Mooring components<br />
• Mooring Design challenges<br />
• Mooring Installation challenges<br />
• Mooring Polyester rope challenges<br />
• Mooring component Quality<br />
4<br />
2012-09-26
Mooring System Design Requirements<br />
• To be according to PSA requirements<br />
• «Easy» installation<br />
• «Easy» replacement of mooring line segments<br />
• 0.8 mm/year corrosion allowance on chain<br />
• Polyester rope shall withstand trawl impact<br />
• Continue production with one mooring line out of service<br />
• Fatigue life 10x design life<br />
5<br />
2012-09-26
Mooring System Design Requirements<br />
Wea<strong>the</strong>r<br />
condition<br />
Intact<br />
One Line<br />
failure<br />
Two Line<br />
failure<br />
Three Line<br />
failure<br />
Normal<br />
operation<br />
100 year<br />
10 year<br />
2.2<br />
Class 3<br />
1.5<br />
Class 3<br />
1.5<br />
Class 3<br />
One line<br />
out of<br />
service<br />
1 year<br />
100 year<br />
2.2<br />
Class 3<br />
1.5<br />
Class 1<br />
1.5<br />
Class 3<br />
1.2<br />
Class 1<br />
1.5<br />
Class 3<br />
6<br />
2012-09-26
Mooring layout<br />
7<br />
2012-09-26
Mooring line components<br />
• 254mm cut resistant polyester rope<br />
• 160mm R4 chain<br />
• Ballgrab style connector<br />
• H-links<br />
• Suction anchors / DPA<br />
8<br />
2012-09-26
Taut leg mooring system<br />
Platform chain: 160mm R4 chain<br />
254mm cut resistant polyester rope<br />
Bottom chain: 160mm R4 chain<br />
Ballgrab style connector<br />
H-links<br />
Suction anchors / DPA<br />
9<br />
2012-09-26
Chain Jacks and fairleads<br />
10<br />
2012-09-26
Design and Installation challanges<br />
Design challanges:<br />
• Easy installable<br />
• Easy replaceable<br />
• Mooring line stiffness<br />
• Construction stress<br />
• Analysis tools<br />
• Extreme loads<br />
• Trawl protection<br />
Installation challanges:<br />
• 1300 m water depth<br />
• First hook-up of <strong>SPAR</strong> with topside<br />
installed<br />
• NO twist in mooring lines<br />
• Short installation season<br />
• Qualification of laydown of polyester rope<br />
• Polyester rope creep<br />
• Limitations from design<br />
11<br />
2012-09-26
Polyester mooring line challenges<br />
• Damages due to Trawlling<br />
• Internal abrasion due to sand ingress<br />
+ Polyester stiffness<br />
12<br />
2012-09-26
Polyester rope stiffness<br />
• Stiffness is non-linear<br />
• Polyester rope length «changes»<br />
Permanent elongation<br />
13<br />
2012-09-26
Polyester rope prelay qualification<br />
Ongoing fullscale offshore test:<br />
• Does a rope lay stable on <strong>the</strong> seabed at <strong>Aasta</strong> <strong>Hansteen</strong>???<br />
• 75m 226mm polyester rope laid down October 2012<br />
Furter work:<br />
• Monitor current at <strong>the</strong> location<br />
• Verify actual polyester ropes sand filter with <strong>Aasta</strong> <strong>Hansteen</strong> soil<br />
14<br />
2012-09-26
Cut resistant polyester rope<br />
• Testing requirements are made<br />
• <strong>Aasta</strong> <strong>Hansteen</strong> Design Loads are<br />
established<br />
• Different designs are tested<br />
15<br />
2012-09-26
Quality !!<br />
• Certification of components is not enough!!<br />
• Extended QC of chain and coupling elements:<br />
− Additional inspector<br />
− Extended MPI-testing<br />
− Extended verification of UT<br />
− Follow up of steel manufacturer<br />
• Same quality level for polyester rope QC<br />
16<br />
2012-09-26
<strong>Aasta</strong> <strong>Hansteen</strong> – Worlds <strong>largest</strong> <strong>SPAR</strong><br />
Øystein Gabrelsen<br />
E-mail: oygab@statoil.com<br />
Tel: +4797985837<br />
www.statoil.com<br />
17<br />
2012-09-26
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