Offshore Natural Resource Extraction

Overview History History Exploration Exploration  Seismic surveys  Drill ships Platform models Platform models  Fixed Platforms  Compliant Towers  Semi-submersible Platforms  Jack-up Platforms  Tension-leg Platforms  Spar Platforms  Subsea Systems Recent Affairs Recent Affairs

History Companies drilled from piers extending off the beach at Summerland California Companies drilled from piers extending off the beach at Summerland California Gulf Oil drilled the worlds first truly “offshore” well detached from the shore at Caddo Lake, Louisiana/Texas border Gulf Oil drilled the worlds first truly “offshore” well detached from the shore at Caddo Lake, Louisiana/Texas border Although drilling in the Gulf of Mexico has been taking place for some time, Kerr McGee completed first offshore well out of sight of land Although drilling in the Gulf of Mexico has been taking place for some time, Kerr McGee completed first offshore well out of sight of land

1965 – The 5600 ton drilling barge “Sea Gem” was first to discover hydrocarbons in the British North Sea sector 1965 – The 5600 ton drilling barge “Sea Gem” was first to discover hydrocarbons in the British North Sea sector

Exploration Seismic Surveys Seismic Surveys Maps rock layers without drilling a well Maps rock layers without drilling a well Send shockwaves using air guns and record echoes Send shockwaves using air guns and record echoes The time for each echo to return as it bounces depends on depths and properties of rock layers The time for each echo to return as it bounces depends on depths and properties of rock layers Problem: presence of hydrocarbons can only be confirmed by drilling Problem: presence of hydrocarbons can only be confirmed by drilling

Drill Ships Drill Ships Ship with oil derrick on deck Ship with oil derrick on deck Used to quickly drill and check for hydrocarbons Used to quickly drill and check for hydrocarbons Not as stable as other rigs Not as stable as other rigs Very mobile Very mobile

Early ships used anchors to maintain position Early ships used anchors to maintain position Modern vessels use Dynamic Positioning Modern vessels use Dynamic Positioning

Platform Models

Fixed Platform Fixed Platform Used in shallow waters up to 520m Used in shallow waters up to 520m Legs constructed of concrete or steel Legs constructed of concrete or steel Rest on their own masses, very stable in strong winds or rough waters Rest on their own masses, very stable in strong winds or rough waters Designed for long term use Designed for long term use Concrete legs serve as storage tanks Concrete legs serve as storage tanks Gravity base platform being built in Norway

Jack-up Platforms Jack-up Platforms Moving legs attached to platform Moving legs attached to platform Legs can be lowered like jacks and rested on seabed Legs can be lowered like jacks and rested on seabed Designed to easily move from place to place Designed to easily move from place to place Used in relatively low depths (up to 150m) Used in relatively low depths (up to 150m) Problem: cannot be used in extremely deep waters Problem: cannot be used in extremely deep waters

Compliant Towers Compliant Towers Similar to fixed platforms Similar to fixed platforms Used in deeper waters ( 450 – 900m) Used in deeper waters ( 450 – 900m) Slender tower attached to foundation slab on seabed Slender tower attached to foundation slab on seabed Very flexible compared to fixed platforms Very flexible compared to fixed platforms Can sustain significant lateral deflection cause by water movement Can sustain significant lateral deflection cause by water movement Strong enough to withstand hurricanes despite it’s flexibility Strong enough to withstand hurricanes despite it’s flexibility

Semi-submersible Platforms Semi-submersible Platforms Supported by hulls or pontoons Supported by hulls or pontoons Can be ballasted up and down by regulating flooding in buoyancy tanks Can be ballasted up and down by regulating flooding in buoyancy tanks Can be moved from place to place Can be moved from place to place Anchored by cable or dynamic positioning Anchored by cable or dynamic positioning Very stable in rough, deep seas Very stable in rough, deep seas Used in depths from 180 – 1,800m Used in depths from 180 – 1,800m

Tension-leg Platforms Tension-leg Platforms Similar to semi-submersible, consisting of a floating rig Similar to semi-submersible, consisting of a floating rig Attached to seabed by tethers Attached to seabed by tethers Tethers have high axial stiffness which eliminates most vertical movement Tethers have high axial stiffness which eliminates most vertical movement Used in depths of up to 2000 m Used in depths of up to 2000 m Miniature version called Seastar platforms are used in depths between m Miniature version called Seastar platforms are used in depths between m

Examples of Seastar platforms

Spar Platforms Spar Platforms The largest of all platforms The largest of all platforms Consist of a large cylinder used to stabilize the platform Consist of a large cylinder used to stabilize the platform Does not extend to the floor Does not extend to the floor Tethered by lines and cables Tethered by lines and cables Unlike the TLP platforms it has conventional cables but is more stable due to the large ballast Unlike the TLP platforms it has conventional cables but is more stable due to the large ballast

-The Genesis hull, travelling past condominium complex in Port Arkansas, Texas

Subsea Systems Subsea Systems Do no have ability to drill Do no have ability to drill Extract and transport only Extract and transport only Used in depths of up to 2000m Used in depths of up to 2000m Tied in to underwater pipeline or production platform Tied in to underwater pipeline or production platform Avoids the need of production platform for each well Avoids the need of production platform for each well

Summary

Recent Affairs

Hurricane Rita and Katrina Facts Hurricane Rita and Katrina Facts 394 platforms in the path of the storms 394 platforms in the path of the storms 18 rigs suffered major damage or were totally lost 18 rigs suffered major damage or were totally lost 16 rigs damage to varying degrees, up to 2 weeks to repair 16 rigs damage to varying degrees, up to 2 weeks to repair Furthest rig drifted 80 miles during the storms Furthest rig drifted 80 miles during the storms No loss of life No loss of life

- Billiton Oil Platform Beached by Rita, just off of Dauphin Island, Alabama

Chevron’s TLP platform before the storms

- What remains of Chevron’s TLP platform after being hit by hurricane Rita

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