Introduction to Ship-Shaped Offshore Structure

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Introduction:

Ship-shaped offshore structure

IHIAP Offshore Engineering Div

Mohamad Faeze

14TH Jan 2014 Ver 1.0


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Contents

1.1 Historical Overview of Offshore Structure Developments

1.2 Process of Offshore Oil and Gas Developments

1.3 System concepts for Deep/Ultra deep-Water Field Developments

1.4 Brief history of FPSO Installations

1.5 Trading Tankers vs Ship-Shaped Offshore Units

1.6 New Build vs Tanker Conversion

1.7 Layout and General Arrangement of FPSOs


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1.1 Historical Overview of Offshore

Structure DevelopmentsEarly History

Energy is important toprogress of civilization

Industrial advances needscoal, oil, then gas

Exploration initiated ashorethen moved to offshore(late1800s in California)

Early 1930s, oil drilling wasundertaken by derricksystems(timber) located in

waters more than a mile

World War II to Early1970s

In 1946, first steel offshoreplatform of tubular

members was build to 8kmoff coast GoM (4.5m waterdepth, length 53m long,23m wide)

In 1947, more advancedbottom-supportedplatformor jacket-type(JT) that includes

drilling rig and equipmentBy 1970, the operating

water depth for JT reach>80m

After Early 1970s

Impact of world oil shock inearly 1970s had moved

development of offshore oilinto deeper water

Late 1970s, fixed-typeoffshore structure reach300m, >550m in late 1980s

In 1970s, first concretegravity platform build onland(new design concept)

In 1990s began new designconcepts that could beplaced and operated indeeper water, hence era ofFPSO began


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1.2 Process of Offshore Oil and Gas

Developments

ExplorationExploratory

drillingDevelopment

drillingProduction

Storage andoffloading

Transportation


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1.3 System Concepts for Deep- and

Ultra deep-Water Field Developments

Selection criteria

Environment, including water depth

Production capacity

Distance from field to shore or supportinginfrastructure such as pipelines

Required number of drilling centers and wells for eachcenter

Well-fluid chemistry, pressure and intervention orwell-entry frequency for optimum well performance

Risk to personnel

Performance requirementsfor floating-type offshore

Appropriate work area, deck load capacity, possiblestorage capacity

Acceptable stability & station-keeping

Sufficient strength to resist harsh environment

Durability to resist fatigue and corrosion actions

Possible capabilities for both drilling and production

Mobility when needed


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Floating-type offshore structures

Semisubmersibles

Spars

Tension Leg Platforms(TLP)

Ship-Shaped Offshore Units


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1.4 Brief History of FPSO Installations

Oil storage and shuttle tanker-mooring facilities usingconverting trading tankers existed in late 1960s. Thefirst vessels were connected by hawsers to catenaryanchor leg mooring(CALM) systems.

First dedicated FPSO was byArco in Ardjuna field inJava Sea(1976). This was a concrete barge with steeltanks to storage refrigerated LPG moored using a rigidarm system.

First tanker-based single-point moored FPSO facility is

to be Castellon for Shell Offshore Spain(1976)In early 2000s, more than 90 FPSOs were in service and24 FPSOs were under construction.


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Fig1 FSO Ifrika in side-by-

side export arrangement

Fig2 FPSO Castellon at Castellon field

offshore Spain in 1976


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1.5 Trading tankers versus Ship-

shaped Offshore UnitsTrading tankers Ship-shaped Offshore UnitsDesign condition : North Atlantic wave

environment

Design condition : Site-and tow-route

specific environments

20 to 25-year return period 100-year return period

Predominantly wave actions Current as well as wind and wave actions

Limited number of loading/offloading

cycles

More frequent loading/offloading cycles

At open sea for about 70 percent of the

time

Offshore for 100 percent of the time

Weather in any direction; rough weather

avoidance possible

Highly directional weather and

weathervaning; rough weather avoidance

not possible once on site

Regular dry-docking every 5 years Continuous operation usually without

dry-docking

Without topsides With topsides and associated interaction

effects between hull and topsides


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1.6 Newbuild versus Tanker Conversion

Newbuild Tanker Conversion

Design and fatigue lives for a field can be

achieved easier

Capital costs can be reduced

Technical, commercial, and environmental

risks can be more easily contained

Design and construction schedule can be

faster and less extensiveA system can be more easily designed to

survive harsh environments

Construction facility availability is

increased

Resale and residual values can be

maximized

Overall project supervision requirements

can be less

Reusability opportunities can be improved


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1.7 Layout and General Arrangement

of FPSOsFactors affect deck

area and GAHull form

Turret location and size

Accommodation location and size

Ballast capacity and distribution

Double-side or double-bottom requirement

Escape, evacuation, and rescue arrangements

Offloading arrangements

Margins for future process upgrading and expansion

Layout can bedivided into:

Main deck

Topsides deck

Mooring system

Accommodation

Machinery room

Cargo and ballast tanks

Offloading area


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Reference

Guide of building and classing floating

production installations. ABS(2004)

Introduction to offshore structures Design,fabrication, installation. Graff,W.J(1981)

Floating storage units and shuttle tankers of

the world. OPL(2002)

Handbook of ocean and underwaterengineering. Myers,J. J., Holm, C.H., andMcAlister,R.F.(1969)

Introduction to Ship-Shaped Offshore Structure

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