Guidelines on Late Life Decommissioning Inspection and Maintenance Secured

7/24/2019 Guidelines on Late Life Decommissioning Inspection and Maintenance Secured

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This document was prepared by the members of Oil & Gas UKs Decommissioning Efficient

Execution Workgroup. Particular recognition is given to the input of Ian Fozdar who led the activity.

Issue 1 - 2015 Edition

ISBN: 1 903 004 57 8


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Guidelines on Late-Life/DecommissioningInspection and Maintenance

Contents

Foreword

Paragraph Page

1.

Introduction 1

2.Offshore Decommissioning Workflow 2

2.1 Definitions of the Decommissioning Phases 2

3.Late-Life/Decommissioning Cost Reductions 5

4.

Inspection and Maintenance Assessment Process 8

4.1 Inspection and Maintenance Framework 8

5.Implementing the Framework 11

Appendix 1 13Abbreviations 13

Appendix 2 14

Worked Example Operations, Inspection & Maintenance Framework 14

Table

Table 1 Hazard and Safety Critical Elements Matrix 8

Table 2 Operations Inspection & Maintenance Framework 10


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1. Introduction

Maintenance during the late-life and decommissioning phases of infrastructure

is driven by very different objectives and constraints than during the steady-

state Operating phase.

Robust Health, Safety and Environment (HSE) management is now typically

in the context of reduced hydrocarbon inventories and pressures.

Production-critical maintenance typically becomes more reactive, and then

ceases.

Equipment and human-access related maintenance becomes solely driven

by the needs of decommissioning/dismantlement, which were virtually non-

issues during the Operating phase.

Inspection may be designed more to understand the condition of a platform,

so that decommissioning plans can be fitted to this, and less to confirm thatsome pre-determined performance standard is being met.

Overall Inspection/Maintenance man-hours and costs can be reduced, often

significantly, during decommissioning. The challenge is to avoid the threats to

safety and integrity throughout the project. The experience of Oil and Gas UK

members has produced two matrices to provide:

An enabler for managing the changing HSE hazards during late-

lif /d i i i


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2. Offshore Decommissioning Workflow

As the workflow moves through each Decommissioning Phase the inspection

Need to managefor productionphase & futuredecom phase

needs

Need to manageSafety CriticalElements &

current/futuredecom phase

needs

Need to manage reducing no. of Safety Critical Elements, and inspect/maintain

for current/future decom phase needs

End of production-related

insp./maintenance


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o Environmental Management System: All environmentally criticalelements defined the Environmental Management System for thelevel of suspension are to be inspected/maintained.

Warm Suspension, Live Wells (only applicable for structures with

wells)

o The platform/subsea structure has permanently ceased production.o Wells: All wells have not been permanently Plugged and

Abandoned.o Pipelines: Import & export pipelines have been decommissioned.o Secure from health, safety and environmental hazards to agreed

standards.o Topsides: Process pipework has been decommissioned from the

riser to the production tree of each well, and to any connectedplatforms.

All process equipment (compressors, pumps, control systems,etc) decommissioned ready for removal

Secure from health, safety and environmental hazards toagreed standards.

o Safety Management System: All Safety critical elements defined inthe Safety Management System for this level of suspension are tobe inspected/maintained.

o Environmental Management System: All environmentally criticalelements defined in the Environmental Management system for thislevel of suspension are to be inspected/maintained.

Warm S spension (Li e Process)


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Secure from health, safety and environmental hazards toagreed standards.

o Manning:

Manned: The platform is manned, with accommodation,personnel welfare systems and utilities inspected andmaintained to agreed standards.

Unmanned: The platform is normally unmanned, with requiredemergency refuge, personnel welfare systems and utilities

maintained to agreed standards.o Safety Management System: All Safety critical elements defined in

the Safety Management System for this level of suspension are tobe inspected/maintained.

o Environmental Management System: All environmentally criticalelements defined in the Environmental Management system for thislevel of suspension are to be inspected/maintained.

Partial Removal, manned or unmanned

o The platform/subsea structure has permanently ceased production.o Wells: All wells have been permanently Plugged & Abandoned and

conductors cut below seabed at agreed depth.o Pipelines: Import & export pipelines have been decommissioned.o Secure from health, safety and environmental hazards to agreed

standards.o Topsides: Process pipework has been decommissioned from the

riser to the production tree of each well, and to any connected

l tf


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3. Late-Life/Decommissioning Cost Reductions

The sources of cost reduction are typically driven through reductions in

inspection, maintenance and consumables needs. Some examples of direct

and indirect cost savings may include:

Experience from infrastructure in the other regions indicates that inspection &

maintenance during decommissioning can be safety and steadily downscaled

through effective management of activities.

Th h t Fi 1 b l ill t t t d f t i lth h t

Direct Savings Offshore manhours

Onshore manhoursSpare parts and Inventory

Indirect Savings Documentation reduced

Helicopter flights / Supply boats

Accommodation costs

Manager and Technical Authority time

Other Benefits HSE improvements as fewer man-hours offshoreFocussed maintenance leads to better reliability


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Decommissioning Phase: Potential high intensity activity:

Warm Suspension / Warm Stack Freeing of hydrocarbons and wellplugging & abandonment

Engineering and installation of lift points

Removal Removal, including use of barges andheavy lift vessels

Dismantle and Dispose Dismantling and disposal


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a) Large, Manned Installations

Limited scope for pre-cessation cost reductions due to high fixed OPEX & startof decommissioning

b) N ll U d I t ll ti (NUI


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4. Inspection and Maintenance Assessment Process

This section describes a process by which inspection and maintenance

requirements during the late-life and decommissioning phases can be

assessed.

4.1 Inspection and Maintenance Framework

A key difference between Decommissioning and Production Operations is thetype of hazards encountered. During production, the hazards remain constant

(such as loss of containment) whereas the hazards encountered duringdecommissioning change substantially from Cessation of Production (CoP) tocompletion of the decommissioning project, typically reducing as the

decommissioning phases are progressed.

Certain hazards will disappear as decommissioning progresses (e.g. with

removal of process hydrocarbons, there is no risk of Loss of Containment). It

may also be that the risk of Fire and Explosion is not present, depending onwhether factors such as presence of utility hydrocarbons such as diesel.

One of the keys to reducing inspection and maintenance is the efficientmanagement of changing safety requirements.

A useful tool to ensure that all hazards are recognised and properly managedis to build a Hazard and Safety Critical Elements Matrix.

T bl 1 b l t l H d d S f t C iti l El t M t i


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When all hazards associated with a given SCE have been eliminated, bydefinition that SCE becomes redundant, and inspection/maintenance for it may

be discontinued.

This justified reduction in inspection/maintenance can then be mapped on to a

Operations, Inspection & Maintenance Matrix, as illustrated in Table 2. Thisallows the changes in Inspection & Maintenance requirements to be mapped-out in advance.

The horizontal axis indicates the decommissioning phase that a platform is in,and the vertical axis the various equipment and systems for which maintenance

is being managed.

Based on the HSE logic illustrated in the Hazard & SCE Matrix shown before,

justified reductions in HSE-related inspection/maintenance can be agreed and

summarised in this table.

The format is generic, and the titles on the 2 axes (horizontal & vertical) can be

modified as required to fit internal workflows and maintenanceframework/definitions.

In some cases (life boats, walkway gratings etc.) no reduction in inspection &maintenance can be achieved regardless of whether a platform is operating or

in the decommissioning phase (e.g. a manned platform will have evacuationneeds even when hydrocarbons are removed). This unchangedinspection/maintenance regime is referenced by a green-coloured cell.

Wh ti l d ti i i ti & i t f ibl b


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10 October 2015

Operations & Maintenance framework Bases for Inspection & MaintenanceStrategy

Health (Present, Future)

Legend Safety (Present, Future)

Fully Maintained Environment (Present, Future)Partially Maintained Reliability (Present, Future)

No maintenance Production Phase Warm Suspension (Fully Live) Warm Suspension (LiveWells)

Warm Suspension (LiveProcess)

ColdSuspension

PartialRemoval

Performance Standards (Present,Future)

Pre-late life Late life Insp. &Maintenance

Final Clean &Disconnect

Plug &Abandon

Insp. &Maintenance

Plug &Abandon

Insp. &Maintenance


EQUIPMENT /ITEM

SCE COMMENTS

HSE

HSE

HSE

HSE

HSE

HSE

HSE

HSE

HSE

HSE

Production

Production

Production

Production

Production

Utilities

Utilities

Access

Access

Table 2 Operations, Inspection & Maintenance Framework


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5. Implementing the Framework

An example of how one Operator applied the Operations, Inspection &

Maintenance framework is as follows:

(a) Ensure Governance document exists that drives Business Plan process

to determine premised CoP dates (& uncertainty)

(b) Identify different phases & milestones of late-life & decommissioning

(c) Outline the requirements for the different phases of decommissioning

Modify existing maintenance philosophy & strategy documents

Main focus will be on safety critical maintenance

(d) Several years before CoP, carry-out review of planned & corrective

maintenance routines & budget drivers to identify maintenance work that

can be eliminated during the late-life & decom phases

Carry out risk-assessments / Management of Change (MoCs) as

appropriate.

Ensure discipline Technical Authorities (TAs) are involved

Regulatory & industry standards to be maintained where required.

incl. Safety Case & Verification and Examination Scheme (VES)

programme

( ) Adj t i t t t t fl t h ( SAP


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Appendix 2 presents a worked example of the Operations, Inspection &Maintenance Framework.

The example shows a limited number of line items for visibility, although inpractise there could be a much larger number of systems on platforms which

offer potential for changed inspection/maintenance.


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Appendix 1

Abbreviations

CoP Cessation of Production

ERRV Emergency Response and Recovery Vessel

HSE Health, Safety and Environment

ICP Independent Competent Person

IVB Independent Verification Body

MoC Management of Change

NavAids Navigational AidsNUI Normally Unmanned Installation

P&A Plugging and Abandonment

SCE Safety Critical Element

TA Technical Authority

UKCS United Kingdom Continental Shelf


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14 October 2015

Appendix 2

Worked Example Operations, Inspection & Maintenance FrameworkOperations & Maintenanceframework

Bases for Inspection & MaintenanceStrategy

Health (Present, Future)

Legend Safety (Present, Future)Fully Maintained Environment (Present, Future)

Partially Maintained Reliability (Present, Future)

No maintenance Production Phase Warm Suspension (Fully Live) Warm Suspension (LiveWells)

Warm Suspension (LiveProcess)

ColdSuspension

PartialRemoval

Performance Standards (Present,Future)

Pre-latelife

Late life Insp. &Maintenance


Plug &Abandon

Insp. &Maintenance

Plug &Abandon

Insp. &Maintenance


EQUIPMENT /ITEM

SCE COMMENTS

HSEAccumulators &Pulsation Dampers

Reactivemaintenance

HSE

Batteries &UninterruptiblePower Supplies(UPS)

For fire & gas systems &communications

HSE Navigation AidsUtilise rig

navigationalaids

Utilise AWVnavigational

aids

MarkerBuoys

Markerbuoys orRemovalvessel

NavAids

Until buoys are installed, or NUI is inCold Suspension

HSE Distribution Boards Safety Critical equipment only

HSE Earthing/Bonding

HSEDiesel System(Tanks andPipework)

HSE Engines: Diesel

HSEFire & GasInstrumentation

HSEAlternators andGenerators

HSE Lighting

HSEMotor ControlCentres (MCCs)

Safety Critical equipment only

HSE Electric Motors Safety Critical equipment onlySafety Critical equipment

only

HSESafe MarineSystem

HSE Small PowerCircuits


HSEElectricalSwitchboard


HSEPortable Electrical

Equipment

HSE Telecoms

HSE Temporary RefugeReduced

inspection/maintenancerequirement if de-pressurised

Guidelines on Late Life Decommissioning Inspection and Maintenance Secured

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