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www.subsea7.comSubsea Partner of Choice 18.01.2008
Development of a New Deep-Water Riser System
Daniel KarunakaranSubsea 7
www.subsea7.comSubsea Partner of Choice 18.01.2008
IntroductionGrouped SLORTM is an ‘open bundle’ riser solution developed by Subsea 7 and 2H Offshore
Array of close standing SLOR’s/COR’s connected together by a buoyant guide frame
www.subsea7.comSubsea Partner of Choice 18.01.2008
Single Line Offset Riser - SLORTM
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ExxonMobil Kizomba A & B SLORTM
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SLORTM and CORTM DesignSLORTM and CORTM
Excellant fatigue performance
Decoupled from vessel motion
Pre-installable
Low vessel
payload
Gas lift capability
Field proven
www.subsea7.comSubsea Partner of Choice 18.01.2008
Multiple single SLORTM
• Spacing
• Clash avoidance - flexibles
• Wake interference of air cans
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Grouped SLORTM Design
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Grouped SLORTM DesignRiser and air can
- Single line or pipe-in-pipe
- Slender air can
Guide Frame- Light weight truss with
buoyancy tanks
- Tethered to suction pile
- Integral receptacles with bearing pads
GUIDE FRAME
CENTRAL FLANGED CONECTION
TETHER
BUOYANCY TANK
SLOR STEM RECEPTACLE
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Grouped SLORTM - ConfigurationTypical 4 SLOR’s/COR’s
- 5 to 6m air can diameter
- 10 to 25m air can length with compartments
- 100 to 150Te base tension
- 50Te tether base tension
- Suction pile foundations
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Grouped SLORTM Design Development• Pipe sizing
• Air can sizing
• Optimization - F/L routing Vessel interface Clearance
• Stability / splay optimization
• Storm / fatigue analysis
• Special joint / forging design
• Installation planning
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Grouped SLORTM - QualificationFinite Element Analysis (FEA)
- Assumed CD of 2.0
- Frame Offset < 2% water depth for deep water (800m), <6% for ultra-deep water (2000m)
- Guide frame typically 150m away from vessel
- Frame bearing loads <10Te, well within capacity of bearing pads
- Riser stroke < 4m
690
700
710
720
730
740
750
-30 -20 -10 0 10 20 30
Distance from Frame Centreline (m)
Elev
atio
n fr
om M
udlin
e (m
)
SLOR Frame
No Current
CD=2.0100yr Current
CD=10100yr Current
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Grouped SLORTM - QualificationComputational Fluid Dynamics (CFD)
- Confirm hydrodynamic coefficients employed in FEA
- Drag coefficient (CD) < 2.0
- Air can spacing of 1.0 diameter gives best response in terms of VIV, wake effects and galloping
- CFD further verified using model tow test
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Grouped SLORTM - QualificationTow Model Test
- Conducted in MARIN’s test centre in Holland
- Model towed at speeds up to 0.7m/s
- Incidence of model to flow is varied
- Air can separation increased from 0.5D – 2.0D
- CD ~ 1.0 to 1.5 for air can spacing of 1.0 time diameter
- No possibility of clashing between air cans
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Full Grouped SLORTM Model Test•MARIN (in Netherlands) was engaged to conduct the model test of Grouped SLOR involving for a water depth of 800m
•Model scaling of 1:73 is adopted
•Model test results gathered should be applicable for deeper water depth
•Results indicate VIV response of risers in Grouped SLOR is smaller than single SLOR
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Grouped SLORTM – Installation AssessmentInstallation of Guide Frame
Installation of Riser- Towing : Tug boats- Reel-lay vessel : Seven
Oceans- J-Lay vessel : Seven Seas
Mating of SLOR/COR with Guide Frame
Installation of Flexible Jumper
Seven Oceans
Seven Seas
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Grouped SLORTM – Installation AssessmentRiser Installation by J-Lay
- Subsea 7 Vessel – Seven Seas
- Assembling of double joints
- Lower riser components via the moon pool using the A&R wire
- Cross-haul operation to transfer riser to main crane and auxiliary crane for connecting riser bottom assembly
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Conclusions•Well developed riser solution for deep and ultra-deep water environments.
•Concepts are qualified
•Eliminate clearance issue with good fatigue performance.
•Installation flexibility.
•High usage of local content.
www.subsea7.comSubsea Partner of Choice 18.01.2008
subsea partner of choice
Contact Information:
Daniel Karunakaran,Subsea 7
Daniel.Karunakaran@subsea7.com
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