Rowan Patterson - EEEGR

Rowan Patterson
Business Development Manager
Claxton Engineering
Structural integrity of aging assets and effects
of asset life extension

Structural Integrity of Ageing Assets
and effects on Asset Life Extension
Rowan Patterson SNS 2013

Structural Integrity of Ageing Assets
and effects on Asset Life Extension
Presentation Overview
Introduction
Structural Integrity and Asset Life Extension
Regulations
A Suppliers View
Case Studies
Decommissioning
Summary

About Claxton
What we do…
Engineering and services, for well
systems, structures and pipelines
across the life of assets from
pre-drilling to drilling, production
and decommissioning.

Claxton’s vision
To become the first point of call for the global jack up drilling,
production and decommissioning communities, in the areas where
we operate by providing responsive engineering and services.

Global reach…

Our products…
1. Crane Boom Cameras
2. Wellhead design/supply
3. Cold Cutting
4. Equipment Rental
5. Tensioning Rings &
Tension Systems
6. Drilling Risers/Riser Design
7. Subsea Cameras
8. Tieback Tooling
9. Drilling Templates
10. Rig less Operations
11. Subsea Manifolds
12. Subsea Well
Abandonment
13. Protective Structures
14. Wellhead Maintenance
15. Hot Tapping
16. Equipment Repair and
Refurbishment
17. Workovers
18. Cellar Deck Centralizers
19. Decommissioning and
Abandonment
20. Structural Centralizers
21. Asset Life Extension
22. Slot Recovery
23. Cement Top Up
24. Abrasive Cutting
25. Internal Centralizers

Structural Integrity and Asset Life Extension
Maintaining Structural Integrity of an asset through its life involves dealing with ageing - 30%
of worldwide offshore structures are more than 20 years old
Operational incidents:
dropped objects, collision, impact
Overload:
rig less well work-overs, additions,
modifications, wind and waves
Corrosion damage
Fatigue damage – offshore environment is
dynamic and constantly moving
Extensions – slot recovery/additions
Subsidence of the field and local foundations
Repair
Decommissioning

Structural Integrity and Asset Life Extension
Regulations
HSE Offshore Information Sheet No. 4/2009
Provides general guidance for asset managers, safety managers and safety
engineers on management of ageing installations (the duty holders)
The Offshore Installations (Safety Case) Regulations 2005 (SCR05)
Requires the duty-holder to carry out a 5-yearly thorough review of the safety case

Offshore Installations (Safety Case)
Regulations 2005 (SCR05)
The purpose of regular reviews is to ensure;
The safety case as a whole continues to be fundamentally sound
The relevant statutory provisions are being complied with, taking account of all
relevant changes and new knowledge since the case was last accepted
The safety case continues to demonstrate the effective identification,
management and control of major accident hazard risks on the installation

Offshore Installations (Safety Case)
Regulations 2005 (SCR05)
This means
The installation can continue to be safely operated and
meets:
The required performance standards
Compliance with the relevant statutory provisions
Considers new knowledge, current good practice and any changes
that may have occurred due to ageing
Demonstrates the integrity of the asset to meet regulations
Enables asset life extension and modification

A supplier view of structural integrity
management to meet requirements of
asset life extension
Important to maintain structural integrity and keep adequate records
Meets the safety case requirement
Enables efficient response when repair or modifications are required
Alternative is full scale inspection prior to required repair or modification:
Could mean that the asset is not in a condition or suitable for modification
May mean repair to existing facilities/structure before asset life can be extended
Results in potential delays and additional costs £££££££

Asset Life Extension
Asset life extension can be defined as:
The maintenance of asset integrity presented by the ageing process
and or modification
Caring for assets
Managing structural integrity
Understanding and mitigating risks
Keeping adequate records
Includes future modifications
If we can demonstrate the integrity of the asset to meet
regulations – asset life extension and modifications can proceed with
confidence

Examples of Asset Life Extension
Claxton’s Experience;
Rig-less well work over
Jacket guide replacement.
Well load transfer
Well slot recovery
Conductor whipstocks
New well slot installation
Cement top-ups
Curing excessive flow line movement caused by bad or no
centralization of risers
Conductor centralizers
Hot Tapping
Decommissioning platform and subsea wells

A common problem - Riser Centralization
Location and effect of applied loads
Loads not generally well understood
Lateral support for well conductors is
required to withstand loads from
Offset between well and jacket
Riser Rotations
Compression from surface loads
Wave and current loads
Wave action orbital movement
Wave Slam/Impact
2
Cellar deck centralizers
Conductor centralizers
for the splash zone
and subsea guides
Tangential Loads

Riser Centralization
Wave and current effects
Wave and current effects are much
worse in the splash zone
If riser not centralized properly top
rotation will occur
Results in excess tree & flow line
movement
Flow-line movement must be minimized
to prevent fatigue damage
Important to design & maintain as a
system
Platform
Risers/Centralization
Production flow-lines
Riser Top Rotation
Horizontal flow-line Low load movement 20 ~ 50 kN
(2 ~ 5 Te)
Wave and
Current
High load 200~ 500 kN
(20~50 Te)
Medium load 50 ~ 200 kN
(5 ~20 Te)

Conductor Centralizers
Conclusions
Loads are at their maximum in the splash zone
Splash zone is the worst possible environment for corrosion
Centralizer systems must be fit for purpose
Significant/expensive conductor, jacket and flow line damage can occur if
centralizers are omitted or not designed correctly
How not to centralize conductors

Case study - Rig less well work over
A 38-year-old well riser on a normally
unmanned platform in the North Sea
suffered a corrosion/fatigue failure
Complete failure of the 20” conductor and
partial fracture and wear to the
13 3/8” casing.
The failure was approximately 6 metres
below sea level
The well was immediately shut in and a
strategy to plug and abandon the well
developed and agreed.

Case study - Rig-less well work over
Continued
Urgency and cost prohibited the use of a jack up rig
All of the following activities had to be performed via rig less operation, the first of it’s kind:
Inspection of the well riser and the affected platform areas
Detailed risk assessments
Necessary work permits (simultaneous operations)
Mobilisation and set up of rig less well work over equipment
Down hole perforating & cementing operations to
safely plug the well
Xmas tree removal and tubing severance & recovery
Severance of the casing strings below seabed
Recovery of the casing strings
Recovery of the 20” conductor above and below the
fracture point
Back loading of the cut casing sections due to
deck restrictions
Post job report submitted and safety case updated

Case study – Additional guide structure
The task
Riser guide required for additional well:
Location Splash Zone
Seawater exposure
Potential corrosion
Guide subject to high lateral loads
from well riser
Access/safety of operations
Detailed on site survey
Main structural members OK

Case study – Additional guide structure
The solution - Safety and how to install
Build a new assembly to clamp onto the existing structure
Detailed engineering analysis completed
Safety during installation drives design
to meet the relevant industry codes
Rigorous risk assessments at all stages
of design and installation
Full trial assembly onshore
Modular construction enabled
ease of installation
Ability to halt installation
if bad weather dictated

Case study – Additional guide structure
Conclusions
Safety at all times paramount
Detailed on site survey/
essential
Modular design and a flexible
approach ensured a first class
engineered solution
Design and installation of new
structures to old is possible
inspection is
Records and engineering details on
older platforms are often not available
An assets life can be extended by good
engineering and safety practices

Structural Integrity of Ageing Assets and
effects on Asset Life Extension
Decommissioning
Consider in the longer term, the implications for decommissioning
If assets are not maintained to date of decommissioning, large sums of money have
to be spent to enable removal

Structural Integrity of Ageing Assets and
effects on Asset Life Extension
Summary
The importance of maintaining structural integrity of ageing assets
Structural integrity starts with design through installation and carries on through life of the facility
Lifetime maintenance should be addressed as part of the design process
Maintenance of asset integrity throughout the assets life is essential to ensure safety of
operation
Ensure the Safety Case is always up to date
Asset life extension and modifications can then proceed with minimum additional work and cost
Consider the implications for decommissioning

Structural Integrity of Ageing Assets and
effects on Asset Life Extension
Thank you
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