effective multi-subsea field decommissioning project...
TRANSCRIPT
Effective Multi-Subsea Field
Decommissioning Project Experience and Learnings
Glenn Wilson, Hess Ltd
HESS Operational Excellence
Field History
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Ivanhoe Rob Roy Fields
• Discovered in 1975
• On-stream 1989
• Field suspended 2009
• Water Depth 140m (460ft)
• Reservoir Depth 2,438M
(8,000ft)
• Location 110 miles NE of
Aberdeen, Block 15/21a &
15/21b
Fife/Fergus/Flora/Angus Fields
• Discovered in 1991
• On-stream 1995
• Field suspended 2008
• Water Depth 70m (230ft)
• Reservoir Depth 2,570M
(8,550ft)
• Location 211 miles ESE of
Aberdeen, Block 31/26A,
31/27a, 39/1 & 39/2
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Project Timing – Why Now?
• Following CoP, DECC keen to see progress
– Partner redevelopment studies in
parallel
– 4 year field suspension period
agreement
• Asset Integrity of suspended fields limited (5 year)
design life for inhibited systems
• Industry context :
– Significant increase in activity 2012+
– Competition for Resources
– Pressure on prices
• Risk of change to tax relief
• Project continuity
• Partner financial alignment
• Annual suspension cost $12MM net pa
• Conclusion – early execution manages integrity,
meets DECC obligation & minimises cost risk
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Fife/Fergus/Flora/Angus (FFFA) Fields
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Ivanhoe Rob Roy (IVRR) Fields
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Preparatory Work
The regulator recognized that certain works which do not
prejudice decommissioning options should be able to be
carried out before approval of a decommissioning program:
• removal of surface lines between wells and manifolds.
• disconnection and removal of surface Pipe spools…
The value of preparatory work can bring:
a) Removed Floating Facilities and mid water obstructions
early
b) Flexibility in sourcing contractors and vessels at
favourable rates
c) Continuity of Decommissioning Team workload during
Program Approval process
d) Cleared the area in preparation for Heavy Lift vessel
recovery of Manifolds and sim-ops…
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Deposits in the Sea (Rock Dumping)
Two different styles of protective mattress construction
were used during installation of the pipeline systems.
a) Polypropylene rope and
b) Plasticised Steel wire
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Posted Rock Profiling
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Lessons Learned JOAs - Questions
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• Need to determine at what point in time you agree Asset
CoP and when to start ARO activities...10 yrs...5 yrs. .. or
1yr before?
• Decommissioning Operator wording...needs to include this
as a final phase in the asset life cycle?
• Funding securities? Understanding Tax treatment ?
• Need to develop an internal technical check list if you
purchase or sell an asset that addresses the aspects of
Decommissioning liability?
• Does voting change?
• Need to understand how to manage and communicate the
transition from Opex/Capes to Abex decommissioning
costs....you are moving into a major project phase again?
• Multi year Decommissioning project budgeting essential.
• ARO estimating management?
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Uisge Gorm
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AH001
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Facilities
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• Pipeline infrastructure flushing regime
• Flexible riser integrity
• Disconnect pipeline infrastructure from well
pressure source during initial shutdown phase
• Degraded integrity of structures on seabed
• Product management after recovery
• Data history & Contract Strategy
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Operational Challenges
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Operational Challenges
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Operational Challenges
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Operational Challenges
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IVRR manifold recoveries
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Vessel Operations
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Operational Challenges
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Operational Challenges
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Well P&A
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Hess Well P&A Program to date
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LEAN Management
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Well P&A Phases’ FFFA
4.02
11.32
3.34
2.40 2.04
8.20
2.56
1.67
2.25 1.89
0
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Phases
Decommissioning Phase average
1. Tree Cap recovery. Run EDP / LRP &riser.
2. Re-enter the well and establish barriers
3. Recover tree and run / latch BOP’s
4. Recover completion.
5. WBCU & E line USIT Log
6. Set cement barriers or section mill andcement.
7. Cut and pull casing (s) and setenvironmental barrier(s)
8a. Pull BOP’s only
8b. Cut & Pull Casings & WellheadSeverance & Recovery
9. Skid Rig/Sea fastening and anchorhandling
Average 39.71 days
per well
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Scaled Production
Tubing
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FFFA
• A13x 23.53 days 28 ft (lost window) & 200 ft
• F7 18.81 days 84 ft (lost window) & 2 x 85 ft windows
IVRR
• IE32 3.18 days & 3.12 days 100 ft window & 100 ft
window
• IG30 3.04 days & 2.87 days 80 ft window & 100 ft window
• II29 1.9 days 100 ft window
Milling Performance Improved
75% Equivalent Flow
25% Equivalent Flow
Cooling the milling face causes
the steel to brittle form and break
Off in smaller chips.
Agreed to machine bottom sub
To incorporate 6 nozzles, slightly
Offset from body axis, angled in
Front of cutting face.
8¼
“ O
D
Stabiliser lug and knife retainer/ Drift ø of casing
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Well P&A Challenges
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• Significant project.
• ”Unknown unknown” legacy wellbore conditions.
• Uncertainty of effective reservoir isolation, due to
deterioration of production casing annular cement.
• Complex side-tracked wellbores with added uncertainty
from previous non-productive leg abandonment
practices.
• Over-pressured reservoir
• Post Macondo, abandonment practices received greater
industry and legislative body attention.
• Developing a consistence set of recommended practices
to effectively abandon North Sea wells in line with Hess
Global standards, UK O & G guidelines and UK
legislative expectations.
• Subsea well Intervention equipment availability.
• Tight rig market
• Experienced personnel, both operator and Service Co.
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Decommissioning Achievements / Learnings
● Hess P&A team in place a year before operational start-up
● Schedule wells with minimal challenges early
● Long term contracts with key suppliers delivers financial and project benefits.
● MODU secured for both phases of campaign at favourable market rates.
● Frequent Management of change
● NORM (Scale) handling procedures
● Down hole scaled completion; Understanding & practices advanced.
● Careful handling of wellbore fluid (Slops) requires continual awareness to
ensure legislative compliance.
● Combination Isolation scanner and CBL/VDL technology successful in
verification of annulus cement bond integrity.
● Real time cement bond evaluation involving Hess global specialists,
Contractor real time centre and 3rd party independent verification
● Hess global cement specialist instrumental in working with cementing
service company
● Long term relationship with rig contractor enhances lessons learnt capture,
operational team work and performance.
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Technology focus areas
• A means to demonstrate the integrity of casing cement in an
existing well that does not require the removal of the completion
(enables rigless through tubing plug deployment). e.g. Logging
technology/interpretation
• Cements that do not age or crack on thermal cycling (helps well
integrity, reduces the length of cement plug required on P&A).
• Tubing scale removal, chemical or mechanical technology.
• Plugging and perforating technology within scaled tubulars.
• Improved casing and zonal isolation technology.
• Improved milling operations and tools.
• Improvement in techniques for dealing with Naturally Occurring
radioactive material
• Wellhead installed, reliable sand monitor…Well Integrity
Programmes
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Global Decommissioning Excellence
• Well Lifecycle design - monobore completions subsea with
reduced ID liners result in mechanical access difficulties due to
close tolerances involved with small tools
• Well Lifecycle data & Integrity - ensure sidetracked legs are
abandoned to Corporate standards prior to drilling further legs
• Well lifecycle management - have a scale management
programme for production well life (downhole as well as at trees)
• Well lifecycle design/operation - ensure hydraulically actuated
swab valves on production trees – NOT manual or ROV only.
Reduces the risk of escalating access issues
• ARO standardization and Global management
• Decommissioning Expectations development
• Stakeholder engagement and regularly compliance
• …..Knowledge and understand.
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FFFA Today
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IVRR Today
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