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8/13/2019 2011 - Single vs Dual Barrier Drilling Risers - Tim Eyles 2H
http://slidepdf.com/reader/full/2011-single-vs-dual-barrier-drilling-risers-tim-eyles-2h 1/20
8/13/2019 2011 - Single vs Dual Barrier Drilling Risers - Tim Eyles 2H
http://slidepdf.com/reader/full/2011-single-vs-dual-barrier-drilling-risers-tim-eyles-2h 2/20
Single / Dual BarrierHP Drilling Risers
Acteon HPHT Subsea Community Breakfast Meeting
23rd March 2011
Tim EylesDirector2H Offshore [email protected] / +44 1483 774908
8/13/2019 2011 - Single vs Dual Barrier Drilling Risers - Tim Eyles 2H
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Agenda
IntroductionDrilling Riser ConfigurationsDeepwater TLP Drilling RisersJack-up Drilling RisersConclusionsReferences and Further Reading
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Introduction
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Why are some deepwater HP drillingrisers dual barrier?
What is currentindustry bestpractise?
Why are most jack-up drilled tie-backwells drilled with asingle barrier HPriser?
Is a dual barriersystem lower riskthan a singlebarrier?
8/13/2019 2011 - Single vs Dual Barrier Drilling Risers - Tim Eyles 2H
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Drilling Riser Configurations
Shallow water – Jack-upSurface wellhead (Platform)
Surface BOPConductor/casing strings continuedNo dedicated drilling riser
Subsea wellhead (Tieback)
Surface BOP + High pressure drilling riser Avoid use of floating drilling unit
Deep waterSurface wellhead (Spar/TLP)
Surface BOP + High pressure drilling riserSubsea wellhead (Tieback - Floating Drilling Unit)
Subsea BOP + Low pressure drilling riserSurface BOP + High pressure drilling riser
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8/13/2019 2011 - Single vs Dual Barrier Drilling Risers - Tim Eyles 2H
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Drilling Riser Configurations
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8/13/2019 2011 - Single vs Dual Barrier Drilling Risers - Tim Eyles 2H
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High Pressure Drilling RisersExisting Barrier Philosophies
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Jack-up UnitTieback wells
Spars/TLPs
e.g.Shell MarsBP Horn MountainChevron Bigfoot
Floating Drilling Unite.g.
Total Donggalla (13-3/8”)Ophia/Shell (13-3/8")
Single Dual
Spars/TLPse.g.
Dominion Devils TowerStatoil Snorre
8/13/2019 2011 - Single vs Dual Barrier Drilling Risers - Tim Eyles 2H
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Deepwater TLP Drilling RisersPrimary drivers for dual barrier
Riser mud pressure significant contributionRiser mud loss could compromise well control
Excessive weight with a single barrier riserTensioner limitations
Excessive wall thickness with a single barrier
Pipe availabilityWeld quality
Local legislationSeen as “best practise”
8Shell Mars TLP
8/13/2019 2011 - Single vs Dual Barrier Drilling Risers - Tim Eyles 2H
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Deepwater TLP Drilling RisersDesign Selection Process
CAPEX – CAPital EXpenditure
OPEX – Operational EXpenditure
RISKEX – RISK EXpenditure
RAMEX – Reliability-Availability-Maintainability EXpenditure
Profit = Max(Revenue-CAPEX-OPEX-RISKEX-RAMEX)
Ref: Deepwater Development Lifecycle Costs for SubseaSystems JIP (1999)
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8/13/2019 2011 - Single vs Dual Barrier Drilling Risers - Tim Eyles 2H
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Deepwater TLP Drilling RisersDual Barrier Pros & Cons
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Pros
Inner string failure may not result in loss of well control Lower RISKEXCan monitor annulus pressure for leaks (small volume) Lower RISKEX
Reduced wall thickness (esp. if diff. pressure ratings) Lower CAPEX
Less demanding weld/material criteria Lower CAPEXReduced system weight (esp. if diff. pressure ratings) Lower CAPEX
Can continue drilling operations if small annulus pressure Lower RAMEX
Use inner string as casing on next well to improve wearmanagement Lower RISKEX
Easier mud control (smaller volume) Lower OPEX
Better cuttings management Lower OPEX
8/13/2019 2011 - Single vs Dual Barrier Drilling Risers - Tim Eyles 2H
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Deepwater TLP Drilling RisersDual Barrier Pros & Cons
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Cons
Increased riser hardware Increased CAPEXIncreased riser running time Increased OPEX
Increased riser weight (esp. if matched pressure ratings) Increased CAPEX
Reduced flexibility for optimised casing hanger andprogramme Increased OPEX
Limit on maximum number of casings Increased OPEX
Increased number of components (may have common
failure mode)
Increased RISKEX
Requires a good metal-to-metal seal at seabed Increased RISKEX
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Deepwater TLP Drilling RisersSelection Process
Final selection should depend on full development lifecycleCAPEXOPEXRISKEXRAMEX
Different operators will have different EXpenditure profilesOutcome location, operator and market dependent
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Jack-up HP Drilling RisersDesign Challenges
Increasing pressure, temperature, waterdepth, harsher environmentDemanding fluid compositionsReduced desirable risk profileIncreasing CAPEX
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Increased wall thickness & riser weightHigh tensioner utilisationsRig modificationsSusceptibility to fatigue
Wave driven Vortex-induced-vibration
Increased riser wellhead loading/utilisationIncreased vessel motion
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Jack-up HP Drilling RisersSelection Process
Consider project
CAPEXOPEXRISKEXRAMEX
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Jack-up HP Drilling RisersSingle Barrier System Considerations
Reducing OPEX Perform regular maintenance and inspection
Reducing CAPEX Consider high strength materials
Reduce wall thicknessReduce riser weightReduce rig modificationsDecrease tensioner utilisation
Consider alternative connection systems
Reduce need for integral forgingsPermit high strength materials
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Conclusions
Selection of single or dual barrier systems should betaken on a case-by-case basisShould consider
CAPEXOPEX
RISKEXRAMEX
Higher pressure, temperature and water depth, harsherenvironments and internal fluids increase the need for an
assessment to be performedHowever a dual barrier system may not always givereduced risk
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Questions?
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