Offshore Platform Technology

8/8/2019 Offshore Platform Technology

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Offshore Platform Technology

Dan Dolan

MMI Engineering

Oakland California


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Offshore Platform Technology

Current offshore wind power platforms The application of offshore oil and gas

technology to offshore wind Current efforts on the development of

design standards for offshore wind


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Definitions

Waterline

Mudline

Support

Structure

Tower

Substructure

Foundation


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Current Practice - Monopiles Most widely used

Very simple design

Installations up to 16 ftdiameter

Driven or drilled into place

Lateral load capacity islimited

Performs best in shallowwater

Sites in 65 ft water depthsHorns Rev


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Current Practice Gravity Base Structures Fewer existing applications

Steel or concrete

Provides some additionalinstallation options

Seabed preparation is

required Scour can be a problem

Overturning is resisted

through weight Performs best in shallow

water

- Sites in 30 ft water depthNysted


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Current Practice Jackets

Beatrice

Fewest existing

applications Multiple, smaller piles

More complex designand fabrication

Strong and stiff

Can be used in

deeper water sites


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Current Distribution

Offshore Wind Farm Installations

0

5

10

5 10 15 20 25 30 35 40 45

Water Depth (m)

Number


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Concept Selection

Concrete

Monopiles

Bottom

Founded

Gravity Base

/Mat

Foundations

Pile Founded

Self Floating Lift InstalledMultiple Pile

Systems

Braced

CaissonsJackets

Compliant

TowersSteel

Floating

Tension Leg

Platform

Centenary

Moored

Spars Calm Buoys

Bottom

FoundedFloating


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Floating Concepts

Many hull shape and mooring

alternatives

Applicable to deep water sites

Extends reach well beyondbottom founded concepts

Eliminates view-shed issues

Potentially lower CAPEX cost

Sea keeping and rotor sensitivityto motion are key issues

Ref Drijftwind


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Range of Concept Applicability

Monopiles

Jackets Floating

Systems

Transition

Depths

Cos

t

Water Depth


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Feasibility of Offshore Wind in the US Offshore wind is a proven technology

Viable options exist today to develop offshoreresources

Major cost reductions will likely come from EPC

competition Innovative construction equipment and techniques

Batch fabrication and construction

Concept refinement will have less impact

New concepts will expand the reach of offshore

development


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Offshore Oil and GasExperience


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Technologies/Experience Over 6,000 platforms

installed to date worldwide

Fixed and floating

Monopiles and complexjackets

Rigid and compliant

Environmental conditions

Hurricane, wind, earthquake,

ice, mudslide 25,000+ piles installed


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Are all oil and gas platforms large?

Is thisrelevant?


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Minimal Platforms


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Gulf of Mexico InstallationsCurrent

~4000 Installations

0

50

100

150

200

250

300

350

400

450

500

10 100 1000 10000

Water depth (ft)

Numb

er

(per20ftincrem

entinW.D.)

Caissons

Jackets

Compliant Towers

Spars

TLPs


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Watch out for the tails

Value

Freq

uency

Load ResistanceFactor ofSafety

Design for 50 year or 100 year storm?


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Storm Overload Examples

Main Pass 209A after Katrina


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Mars TLP after Katrina


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Hurricane Rita Damage


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Typhoon TLP after Rita


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What does O&G tell us? There is no one answer

There are central tendencies but variations aresignificant

There are many options for low cost minimalstructures

Simple solutions are typically more cost effective(less risky) that complex alternatives

Major cost efficiencies will come from EPICcompetition

Innovative construction methods and equipment


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Code Benchmark Joint IndustryProject


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JIP STUDY

Objective

Compare API and IEC standards for OWTG in US waters

Direct comparison

Performance requirements (50 vs 100 year storm)

Design methodologies Reliability assessment

Inherent levels

Regional variability Variability with concept type

Assess cost impact for different performancerequirements


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Sponsors

Germanischer Lloyd

DNV

ABS

Long Island Power Authority

FPL Energy

BP

UPC Wind

Clipper Wind

GE Wind Energy

Southern Company

EPRI

National Renewable Energy Laboratories

Minerals Management Service


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Questions?

Documents

Offshore Platform Technology