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12 Offshore Oil & Gas

Explain the various phases of the

offshore oil-and-gas extraction

Crude and Gas

Oil Reservoir

Gas Reservoir

Oil & GasReservoir

Oil

Water

Gas

Water

Gas

Oil

Water

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Offshore Production Onshore drilling till today

Drilling moves gradually offshore to matchconsumption of energy

Discovery of large reserves of hydrocarbonsunder the seabed floor, for example: Gulf of Mexico 4 billon barrels in 500 1000 m

Compos Basin 3 billion barrels in 400 1000 m

70s & early 80s, drilling in 200 400 m waterdepth

Today, drilling is done in 400 3000 m deep

Compos Basin

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Worlds Oil Reserves Where?

Which country has the highestreserves?

Oil & Gas Journal, January, 2007

How about Natural Gas?

Map of natural gas production from CIA factbook figures

[http://www.cia.gov/cia/publications/factbook/rankorder/2180rank.html]

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Extraction of Crude

1. Exploration

2. Exploratory drilling

3. Development drilling

4. Production operations

5. Transportation of products

1. Exploration Traditional: Seismic survey

Study pressure waves thru Earths crust Locate oil-bearing strata beneath the seabed floor Seismic exploration sends sound waves into the

ground Mobile vessel such core-drilling ship

Others Gravimeters Magnetometers Sniffers

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Environmental Impacts ofSeismic Operations

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2. Exploratory drilling Confirm the presence of hydrocarbon at

the offshore site

Mobile rigs deploy to performexploratory drillingjack-up rig

80-120m

semi-submersible, drill ship

120 - 1000m & more

Drill Ship

Drill ships and semi-submersible rigs are for

drilling in water depths from 120 to 1000+ m Semi-Submersible Rig

Jackup Rig

For drilling in water

depths up to 120m

3. Development drilling

Affirm the presence ofhydrocarbon at the site

Installation of permanent andself-containing structures

Complete with topside facilities(production, accommodation)

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4. Production operation

Drilling is completed, extraction of oilcommences

Production and processing on one platform

A cluster of smaller platforms could be usedfor different operations

5. Storage & Transportation Storage (mainly in production platforms)

Steel jacket platform no storagecapability

Concrete gravity platform temporarystorage

Floating Production, Storage, andOffloading vessels (FPSO).

Bonga FPSO off the coast of Nigeria (1030m)

deployed for processing oil, water and gas

storage capacity of 90,000 to 150,000 bbl

Main dimensions 350 m by 75 m, 345,000 dwt

Transportation

Tankers and barges

Submarine pipelines

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5. Storage & Transportation