1. Subsea Umbilicals and Power Cables
STEEGE Lecture
STEEGE Lecture 44
Thursday 10th April 2008
Darren Patel
Director
d.patel@bpp-tech.com
BPP-TECH
www.bpp-tech.com

2. Subsea Umbilicals and Power Cables
Contents
Contents
1. Introduction to BPP-TECH
2. Description of Subsea Umbilicals and Power Cables
3. Technology Drivers
4. Engineering Challenges
5. Steps to Mitigate Risk
6. Advances in Design
7. Concluding Remarks and Questions

3. www.bpp-tech.com
Company Overview
BPP-TECH
Specialist engineering consultancy, research and product
development services to the offshore hydrocarbon, marine and
insurance industries
• Trading since 1981
• Offices in London, Houston and Aberdeen
• Research and product development
• Flexible pipes, risers, umbilicals & cables
• Floating offshore systems
• Risk assessments, failure studies, claims, losses and
expert witness work

4. Company Overview
Subsea Umbilicals and Power Cables
BPP-TECH carries out:
• Specialist design and analysis services for
the oil and gas industry
• Research and product development
• Independent risk and failure studies,
claims, losses and expert witness

5. Subsea Equipment
System Types

6. Deep Water System Types
System Types
(Source – Offshore Magazine “2006 Deepwater Solutions & Records for Concept Selection Poster”)

7. Oilfield Developments - The Environment
Field Developments

8. Subsea Power Cables
Power Cables
Subsea power cables transmit electric power
between platforms, subsea equipment and the shore

9. Subsea Umbilicals
Umbilicals
A subsea umbilical is an assembly of hydraulic hoses which
can also include electrical cables or optic fibres, used to control
subsea structures from an offshore platform or a floating vessel

10. Subsea power cables
Power cable components

11. Subsea Umbilicals
Umbilical Components

12. Recent Developments
Technology Drivers
Technological advances have largely been driven by the
following:
• Rising demand for oil and gas
• Green concerns
• The need to extract hydrocarbons in deeper water
• Improved reliability and safety
• Extended service life

13. Deep water requirements
are driving a trend towards:
Engineering Challenges
• The development of sophisticated design tools
• More dynamic applications
• Field specific umbilicals and power cables
• Smaller, leaner, light weight designs
• Fatigue resistant, high strength metallic materials
• Polymers that are resistant to the effects of ageing

14. What can go wrong?
Engineering Challenges
1. Incidents during transportation or installation
2. Design flaws
3. Incorrect usage
4. Fatigue failure
5. Manufacturing problems
6. Damage from shark attacks and marine growth
7. Accidental damage
Many of the risks are interrelated

15. Results of a reliability study
on electrical cables in umbilicals
Engineering Challenges

16. Mechanical Failure Modes
Engineering Challenges
• Excessive axial tension or torque
• Excessive bending
• Crushing by excessive external pressure
• Hose/tube bursting by excessive internal pressure
• Layer separation and instability
• Birdcaging
• Loop formation and kinking
• Mechanical degradation - wear and fatigue
• Material degradation-exposure to adverse agents, temperatures and pressures
• 'Problems' with terminations

17. Developments in cross section design and optimisation
Design Tools to Reduce Risk

18. Field Specific Design Developments
Design Tools to Reduce Risk Cross section
design modeling
Obtain distribution
of loads
Design Optimisation
Dynamic simulations
Obtain component
stresses and strains
Service life
estimations

19. Umbilical Developments
Advances in Design • Higher pressure internal hoses
• Increasing use of steel tubes instead of thermoplastic hose
• Fatigue resistant, high strength metallic materials
• Polymers that are resistant to fluid permeation
• Inclusion of high speed optical fibre
• Improved armouring techniques

20. Umbilical Developments
Advances in Design
DUCO Conventional Umbilical DUCO Steel Tube Umbilical

21. Subsea Power Cable Developments
Advances in Design
There is an increasing requirement for:
• Higher voltage, higher power
• Dynamic, light weight, deep water cables
• High flexibility (e.g. for wind and wave energy generation)
The power cable industry needs to respond by developing:
• New light weight, fatigue resistant conductor materials
• Electrically stronger insulation that is resistant to the effects of aging
• Improved armouring materials

22. Dynamic Power Cable Development
Advances in Design
Joint Industry Project

23. Advances in Design
3-Phase a.c. Submarine Power Cable for:
• 132kV, 525A, 100MW
• Deep water
• Long service life
• Aggressive environment

24. Dynamic Power Cable Development
Joint Industry Project
Advances in Design
Work programme
• Cable reliability survey
• Conductor fatigue testing
• Cross Section Design
• Evaluation of Dynamic Performance
• Design optimisation
• Full scale manufacture and testing

25. Renewable Energy
Wind and wave energy generation projects are also
driving developments in submarine power cable
Advances in Design
technology.
Pelamis

26. Conclusions
• Reliability of subsea systems from the mudline to
Conclusions
the sea surface is critical to production in terms of
control and flow assurance
• Umbilicals and power cables are key components
• Materials and design tools have developed
significantly over the last decade to meet tougher
demands from deeper water and renewable
energy applications
• There is a history of installation problems, material
defects and incorrect designs leading to significant
losses

27. tyvm
Thank you for your attention!
Darren Patel, BPP-TECH
d.patel@bpp-tech.com