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CENTRE FOR OFFSHORE FOUNDATION SYSTEMS Part I Introduction to Offshore Structures Hodjat Shiri BSc Civil Eng., MSc Geotech Eng. , PhD (curnt.) Offshore Geotech. Centre for Offshore Foundation Systems (COFS) July 2009

Offshore Structures Slides I

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Page 1: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Part I

Introduction to

Offshore Structures

Hodjat ShiriBSc Civil Eng., MSc Geotech Eng. , PhD (curnt.) Offshore Geotech.

Centre for Offshore Foundation Systems (COFS)

July 2009

Page 2: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Modern Offshore Structure

Piled-Jacket

TLP

Semi-Sub

Page 4: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

The first oil platform in the world is the Oil Rocks (Neft Daşları), built near BAKU in Azerbaijan of Rusiia. Building on the platform began in 1949, with Tankers transporting Oil from the first Well to Baku in 1951. The Oil Rocks lies 45–50 km (about 25 nm) offshore on the CASPIAN SEA.

The most unique feature of the Oil Rocks is that it is actually a functional city with a population of about 5000. The Oil Rocks is a city on the sea, with over 200 km of streets built on piles of dirt and landfill. Most of the inhabitants work on shifts;

“Oil Rocks”The world’s first offshore oil platform built near Baku in Soviet Union, 1949

Page 5: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

“Thames Sea Forts”The World’s predecessors of modern offshore oil platforms,having been pre-constructed in a very short time, during World War II , they were then floated to their location and placed on the shallow bottom of the Thames estuary

Installation sequence

Page 6: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

The Maunsell Sea Forts were small fortified towers built in the Thames and Mersey estuaries during the second world war to help defend the United Kingdom. They take their name from their designer Guy Maunsell . They were decommissioned in the late 1950s and were used for other activities

“Maunsell Sea Forts”The World’s first modern offshore platform

Page 7: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Offshore Structures:• Fixed Structures [ Piled-Jackets, Jackup Rigs, GBS…]• Floating Structures [ Spar, TLP, FPSO, SemiSub,…]

Page 8: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Water Depth• Shallow waters, D < (300~400 m)• Intermediate Waters, (800~1000 m) > D > (300~400 m)• Deep Waters, D > 1000 m

324 m

381 m

Empire State, NY, 1931

Eiffel, Paris,1889

Page 9: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Jacket

Topside

Shallow Water Offshore Complex

Wellhead PLF

Connection Bridges

Wellhead PLF

JackUp Rig

Production PLF

Living Quarter PLF

Flare

Page 10: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Jacket Based Platforms

Jacket

Topside

Page 11: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Platform Compartments

Flare HeliDeck

Cellar DeckMezzanine DeckTop Deck

Boat landing

Conductor Pipes

Utilities

Pedestal Crane

Control Unit

Page 12: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Construction Milestones

• Engineering, Feasibility Study, Conceptual Design, FEED, Basic, Detailed, Shop, Field

• Procurement: heart of Job

• Fabrication, Steel Cutting, Fitting, Welding, Erection, Piping, E&I, Safety, Painting…

• Pre-commissioning, mechanical, E&I, Safety,…

• Load out & Sea-fastening, Yard Preparation, Barge preparation, Grillage Installation, Barge Mooring, Ballasting, Load Transfer, Sea-fastening, Parking…

• Transportation, Pilot Transition, Towing, Field Entering, Positioning…

• Installation, Barge Approach, Mooring, Sea-Fastening Cut, Lifting or Launching, Stabbing, Welding…

• Hook up, Ship Loosed Items, Caisson, Risers,…

• Commissioning• Start up

Page 13: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Load Out & Transportation

Pilotage

Load out

Open Sea Towing

Page 14: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Offshore Installation • Heavy Lifting by Derrick Crane Barges• Floatover by Launch Barges

Jacket lifting

Topside Floatover

Topside Lifting

Page 15: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Jacket

Heavy lifting Derrick Crane Barges

• Revolving Crane Barges• Shearlegs

Revolving CraneShearleg

Page 16: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Platforms Structural Engineering

• Wind• Wave• Current• Earthquake• Ice & Snow• Temperature Variations• Marine Growth• Tides• Seafloor Movements

In-place Analysis / Environmental Loads

• Fabrication Erection Analysis• Load-out Analysis• Transportation Analysis• Installation Analysis• In-Place Analysis

Main Categories :

Page 17: Offshore Structures Slides I

CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

Design Rules & Codes

Platforms Structural Engineering

• Eurocode 8: "Structures in Seismic Regions - Design", CEN (in preparation).

• API-RP2A, "Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms", American Petroleum Institute, Washington, D.C., 18th ed., 1989.

• OCS, "Requirements for Verifying the Structural Integrity of OCS Platforms"., United States Geologic Survey, National Centre, Reston, Virginia, 1980.

• DNV, "Rules for the Design, Construction and Inspection of Offshore Structures", Det Norske Veritas, Oslo, 1977 (with corrections 1982).

• NPD, "Regulation for Structural Design of Load-bearing Structures Intended for Exploitation of Petroleum Resources", Norwegian Petroleum Directorate, 1985.

• BS6235, "Code of Practice for Fixed Offshore Structures", British Standards Institution, London, 1982.

• DOE-OG, "Offshore Installation: Guidance on Design and Construction", U.K., Dept. of Energy, London 1985.

• Eurocode 1: "Basis of Design and Actions on Structures", CEN (in preparation).

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CENTRE FOR OFFSHORE FOUNDATION SYSTEMS

End of Part One

Thank You