Deepwater Installation

1
Deepwater Installation

• of Subsea Equipment

Presenters Name Title Department
2
Why we need to tackle this subject

• The Industry plans to install a lot of subsea
  equipment over the next decade.
• Existing deployment systems have depth
  limitations.
• At 20m/min winch payout and 10m/min recovery
  speeds it takes 5 hours to deploy and recover in
  2000m. Each subsea component will take up to 24
  hours to deploy.
• Equipment location orientation tolerances
  small.
• It is extremely difficult for installation
  contractors to promise an acceptable technical,
  schedule and cost risk for a deepwater project.

3
Why not use a drilling rig?

• Deepwater capable drilling rigs can deploy
  subsea equipment.
• For a project taking some 6 months for
  deployment a vessel costing 300,000 per day
  means a budget of around 54 million.
• A construction vessel deploys faster than a
  drill rig and is 1/3 of the day rate and does not
  tie up scarce drilling capability.

4
Key Technical Issues

• Variable current with time and depth.
• Object geometry variability often highly
  unsymmetrical.
• ROV capability and control.
• Response time to vessel motions and winch speed.
• Line dynamics.
• Steel line strength.
• Durability of fibre ropes.

5
Scale at 2000m
100m length deployment vessel
Seabed
6
Ambitions

• Preliminary views-
• 2500m wd capability by 2005
• Up to 200t objects
• Ability to connect wells and manifolds by jumper
  hoses

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Installation Variables
Ship Deployment Systems
Ship Motions at Surface
Slow winches Envt. may change during deployment
Varying Current
Rope strength varying Tn with depth
ROV umbilical tangle with lowering line
Current load on umbilical
ROV thrust capability control
Added mass
Seabed positioning system capability
2 axis pendulum twist motions
Object settlement and tilt on seabed
8
Potential Sources of knowledge outside the Oil
Industry

• Hydrographic Survey Institutes
• Salvage contractors.
• Deepwater mining contractors.

9
DISH JIP

• JIP launched to-
• Phase 1
• Identify near term and future installation
  requirements.
• Identify current capability.
• Identify what is needed to bridge the gap
  prioritorise.
• Phase 2
• Undertake the development work to deliver the
  prioritorised components, analysis capability and
  procedures.

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JIP Participants

• Operators
• BP, BG, Enterprise, Norsk Hydro, Statoil.
• Installation Contractors
• CSO, DSM, Herema, Oceaneering, Stolt.
• Suppliers
• BMT, Cooper Cameron, Deep Tek, Marlow Ropes
  Nautronix, OTM, Orcina, Scan Rope.

11
Metocean Needs

• Wind wave data at surface for determining
  operability of dynamically positioned vessels.
• Current velocity, direction and persistence
  through the water column.
• Understanding of current generation phenomena and
  ability to predict occurrence and persistence of
  currents above deployment threshold.