Effective Multi-Subsea Field Decommissioning Project...

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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2

3

4

5

6

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8

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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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