Fatigue Performance of Sour Deepwater Riser Welds_ Crack Growth vs. Enduranc
Ci fDt i RComparison of Deepwater Riser Systems …possibility.no/utc2008/ps/B1 - Jean-Francois...
Transcript of Ci fDt i RComparison of Deepwater Riser Systems …possibility.no/utc2008/ps/B1 - Jean-Francois...
Agenda
Factors Influencing Riser SelectionSCR’sFlexiblesMonobore HRT (SLOR)Monobore HRT (SLOR)Bundle HRTField ArchitectureCost ComparisonConclusions
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Factors influencing riser selection
Functional Specification DiameterInternal Pressure, Design temperatureOverall Heat Transfer CoefficientOverall Heat Transfer CoefficientFluid service (H2S, CO2,…WAT)Requirement for riser base gaslift
Characteristics of the fieldWater depthWater depthFPU type and environmentNumber of risers and layout of the wells and manifolds
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Factors influencing riser selection (Continued):
Other factorsAvailability of installation vessels/construction sitePossibility of Installation before FPU arrivalEase of maintenance and inspection (”Integrity Ease of maintenance and inspection ( Integrity management”)
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Steel Catenary Risers (SCRs)
Erha (Acergy EPCI)
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SCRs feasibility
Feasibility is OK when:The thermal insulation requirements are limited: a maximum insulation thickness should not be exceeded to avoid compression issues.For spread-moored FPSO: Fatigue is acceptable at the Touch Down Zone.For turret-moored FPSO: Fatigue of a catenary configuration g y gis likely to be unacceptable and to require alternative SCR configurations (Lazy wave, heavy bottom,…).SCR’s can be installed after FPU arrival: constraint on time to first oil and SIMOPS.
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SCRs feasibility (continued):
Concept advantages DrawbacksNo limitation on water depth.No limitation on pressure.
In-place fatigue is driving the requirements of welding quality, which No limitation on pressure.
No local yard requirement.Low cost.
g q y,decreases laying rate.Riser base far from FPSO (gas lift, subsea (gas lift, subsea processing).Field layout issues to accommodate a large accommodate a large number of risers.
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SCR’s technological envelope
Large diameter, thickness (40mm).Overall Heat Transfer Coefficient: more than 2.5W/m2K Overall Heat Transfer Coefficient: more than 2.5W/m2K (wet insulation).Pipe-in-pipe in dynamic applications is questionable.Temperature limited by flexible joint at FPU (130°C)Temperature limited by flexible joint at FPU (130°C).Capacity of Heavy installation vessel.Capacity of the FPU to accept large vertical loads and increasing with water depth.H2S content degrades fatigue resistance and may require the use of Corrosion Resistant Alloys (CRA), or CRA clad y ( ),pipe.Fatigue and compression at Touch Down Point relates to W/D ratio and FPU motion
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W/D ratio, and FPU motion.
Flexibles
Maximum Water Depth : 1310 m
Water Depth at FPSO : 1050 m
Water Depth at shallow end of Gas import export : 100 m
Frade Acergy (Installation)
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gy ( )
Flexibles: feasibility
Concept advantagesN l l d i
Feasibility is OK when:Th l i l ti No local yard requirements
Can be used in shallow water
D b k
Thermal insulation requirements are relatively low: there is a limitation on the amount of insulation
DrawbacksCost
compatible with installation squeeze loads.Service fluids such as water, oil export gas : there are oil export, gas : there are some limitations on gas service (dewatering and high velocity gas).Risers can be installed after FPU arrival: constraint on time to first oil and SIMOPS.Wellfluid is corrosive
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Wellfluid is corrosive.
Flexibles technological envelope
Diameter: less than 16” Fatigue and fatigue External Pressure (collapse): less than 2500m
The tensioner crushing l d d d f l
assessmentAdvantages
Can be used in “shallow” loads needed for laying and the hydrostatic pressure tend to collapse the carcass and the vault
waterMultibore
the carcass and the vaultThe reverse end cap effect in deep sea, tends to destroy the pipe by destroy the pipe by armours buckling
OHTC larger than 3.4W/m2KTemperature 130°C maximum
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Temperature 130 C maximum
Flexibles logistics
The following table gives an idea of the range of pipe lengthswhich can be accommodated on standard reel and carousel fordifferent diameters
PIPE INSIDE DIAMETER
CAROUSEL REEL
8” 15 000 1 500
12” 7 000 800
16” 3 500 400
Lengths in meters
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g
Monobore tower
XOM Kizomba fieldXOM Blk15 gas gathering (Acergy EPIC).
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Monobore HRTs
FeasibilityNo limitationNo limitation.
AdvantagesLower cost than bundle HRT in Lower cost than bundle HRT in case of a few risers; depending on riser type and service.service.
DrawbacksComplex gas lift systemComplex gas lift system.Riser Interference issues impacting the field layout beyond a few risers
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beyond a few risers .
Bundle HRT
Total Girassol (Acergy EPCI)Total RosaBP Greater Plutonio BP Greater Plutonio (Acergy EPCI)
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Bundle HRTs (Continued):
FeasibilityNo limitation.
AdvantagesAdvantagesLower cost in case of severe functional requirement (thermal insulation, gas lift).Robust field layout, open for future expansion.
DrawbacksDrawbacksRequires a fabrication yard in the geographical area.
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Hybrid riser towers
A vertical structure
Tensioned by buoyancy
composed of various independent risers
Secured by suction pile and flexjoint
Linked to floating facility by flexible jumpersjumpersConnected to flowlines by remotely installed spools
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installed spools
Hybrid riser tower
Technological limitationsTemperature flexible (130°C but at top of risers): High p ( p ) gtemperature flexibles being considered (PEEK).
AdvantagesNo water depth limits.High pressure.Thermal insulation: U-value to 1.7 W/m.K with 150mm of wet insulation or pipe-in-pipe if a lower U-value is required.G lift ithi th tGas-lift within the tower.Insensitive to floater motion.Small load on FPU.Low fatigue damage in placeLow fatigue damage in-place.Installation can take place before FPSO arrival. Large installation vessel/barge not necessary.
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Risers Differentiators
SCR’s Flexibles Multibore Monobore HRT HRT
Water depth: Cost Cost Little Impact Little ImpactDiameter of
d ti li N Li it 10" N Li it N Li itproduction lines: No Limit ~ 10" No Limit No LimitCladding: Cost Cost Onshore Weld Possible Onshore WeldU-value (W/m2.K): >2.5 wet >3.5 wet No Limit No LimitPresence of H2S Cost Cost No Impact No Impacts o o o o pa o paPresence of CO2 Cost Cost No Impact No ImpactWater Injection lining: Cost N/A Onshore Stalk Possible Onshore StalkFPSO t tFPSO turret-moored: Load Load No Impact No Impact
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Field architecture
Field layout arrangement drives the riser type selection.
Management of the available space around the FPUCorridors for future developmentsNumber of risers
Choice between monobore and multibore HRTDistance between towers driven by riser interference (wake shielding and wake instability)
Choice between Catenary / and multibore HRTThe location of the gaslift manifold is a driver of the layout
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Field architecture
SCR/Flexible/SLOR
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Bundle HRT
Field architectureSCRs : ErhaWD: 1200m4 production2 test2 gas lift2 gas lift2 WI1 Gas injection
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Riser selection main driver
Moho-Bilondo(Fl ibl )
Water depthL h l i(Flexible) Low thermal requirement
Dalia(IPB)
Low thermal requirement/Electrical heatingIntegrated gas lift
Bonga/Erha(SCR) No site for riser tower fabricationGreater Plutonio(Bundle riser tower)
Severe thermal insulation requirementIntegrated gas lift, field lay-out, liner for WILocal content
Kizomba(Single riser tower)
No gas liftLimited number of risers
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tower)
Cost differentiation
Differentiation between riser solutions by water depth:
161820 Cost
10121416
SCRHRT
468
10 HRTFlexibles
02
500m 1000m 1250m 1500m 2000m 2500mWater Depth
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Water Depth
Conclusions
All riser systems have their role to playFlexibles have the most severe limitations in diameter water Flexibles have the most severe limitations in diameter, water depth and U-valueSCR’s have limitations in term of U-value (except if PIP)H b id Rise To e s ha e the idest ange of feasibilitHybrid Riser Towers have the widest range of feasibility
It is necessary to evaluate SLOR’s for potential riser interference in the case on many risersB dl HRT’ i f b i ti f ilit i th Bundle HRT’s require a fabrication facility in the area
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Thank you very much for your attention.Any questions?
[email protected]: 1 832 630 2197
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