Prudhoe Bay oil field

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Prudhoe Bay oil field is a large oil field on Alaska's North Slope. It is the largest oil field in both the United States and in North America, covering 213,543 acres (864.18 km²) and containing approximately 25 billion barrels (4,000,000,000 m³) of oil.^[1][2] The amount of recoverable oil in the field is more than double that of the next largest field in the United States, the East Texas oil field. The field is operated by British Petroleum; partners are ExxonMobil and ConocoPhillips.

Contents 1 Location 2 History 3 Geology 3.1 Stats 4 March 2006 oil spill 5 August 2006 shutdown 6 References 7 External links

[edit] Location

The field is located 400 miles north of Fairbanks and 650 miles north of Anchorage, 250 miles north of the Arctic Circle, and 1200 miles from the North Pole.^[1]

[edit] History

Commercial oil exploration started in Prudhoe Bay area in the 1960s and the field was discovered on March 12, 1968, by Atlantic Richfield Company (ARCO) and Exxon, with the well Prudhoe Bay State #1.^[1] In 1974 the State of Alaska's Division of Geological & Geophysical Surveys estimated that the field held 10 billion barrels (1,600,000,000 m³) of oil and 26×10¹² cu ft (740 km³) of natural gas.^[3] Production did not begin until June 20, 1977 when the Alaska Pipeline was completed.^[1] The field was initially operated as two separate developments, the BP Western Operating Area (WOA: Oil Rim) and the ARCO Eastern Operating Area (EOA: Gas Cap).

Cumulative North Slope oil peaked in 1998 at 2 million barrels per day (320,000 m³/d) (Greater Prudhoe Bay: 1.5 million barrels per day (240,000 m³/d), but had fallen to 943,000 barrels per day (149,900 m³/d) in 2005,^[4] while Greater Prudhoe averaged 411,000 bbl/d (65,300 m³/d) in December, 2006 and Prudhoe itself averaged 285,000 bbl/d (45,300 m³/d).^[5] Total production from 1977 through 2005 was 13 billion barrels (2,100,000,000 m³).

As of August 2006, BP estimated that 2 billion recoverable barrels remain and can be recovered with current technology.^[1][6]

[edit] Geology

Oil, condensate and gas are produced from the Triassic, Ivishak sandstone. This reservoir was deposited as a complex amalgamation of fan deltas and alluvial fans. The oil is trapped in the Sadlerochit formation, a gravel and sandstone structure nearly 9,000 feet (2,700 m) under the surface. During the field’s early life the oilbearing sandstone in some locations was 600 feet (180 m) thick. Today, the oil bearing zone's average thickness is about 60 feet (18 m).

[edit] Stats

_{Statistics for the Greater Prudhoe Bay Field.^[1]}

• Discovery well: Prudhoe Bay State #1
• Discovery date: March 12, 1968
• Production start: June 20, 1977
• Total field area: 213,543 acres (864.18 km²)
• Oil production wells: 1114
• Total capacity: 25 billion barrels (4,000,000,000 m³)
  • Produced: 11 billion barrels (1,700,000,000 m³)
  • Total recoverable: 13 billion barrels (2,100,000,000 m³)
  • Remaining recoverable: 2 billion barrels (320,000,000 m³)
• Peak production: 1.5 million barrels per day (240,000 m³/d) (1979)
• Natural gas:
  • Total: 46×10¹² cu ft (1,300 km³) (estimated)
  • Recoverable: 26×10¹² cu ft (740 km³)
• Greater Prudhoe Bay satellite fields:
  • East Operating Area (formerly ARCO)(production start date: 1977)
  • West Operating Area (BP Exploration)(production start date: 1977)
  • Midnight Sun (production start date: 1998)
  • Aurora (production start date: 2000)
  • Orion (production start date: 2002)
  • Polaris (production start date: 1999)
  • Borealis (production start date: 2001)
• Ownership:
  • BP Exploration (Operator): 26%
  • ConocoPhillips Alaska Inc.: 36%
  • ExxonMobil: 36%
  • Others: 2%

[edit] March 2006 oil spill

On March 2, 2006, a worker for BP Exploration (Alaska) discovered a large oil spill in western Prudhoe Bay. Up to 267,000 gallons were spilled, making it the largest oil spill on Alaska's north slope to date.^[7] The spill was attributed to a pipeline rupture.

[edit] August 2006 shutdown

The March 2006 oil spill led the United States Department of Transportation to mandate that the transit lines be inspected for corrosion. As a result, BP announced on 6 August 2006 they had discovered severe corrosion, with losses of 70 to 81 percent in the 3/8-inch of the wall thickness of the pipe. Oil leaking was reported in one area, with the equivalent of four to five barrels of oil spilled.^[8] The damage required replacement of 16 of 22 miles (35 km) of pipeline at the Prudhoe Bay. BP said it was surprised to find such severe corrosion and that it had been 14 years since they had used a pipeline inspection gauge ("pig") to clean out its lines because the company believed the use of the pigging equipment might damage pipe integrity.^[9] BP Exploration announced that they were shutting down the oil field indefinitely, due to the severe corrosion and a minor leak in the oil transit lines.^[9][10] This led to an 8% reduction in the amount of oil produced by the United States of America, as Prudhoe Bay is the country's largest oil producer, producing over 400,000 barrels per day (64,000 m³/d).

BP initially estimated up to 2 to 3 months before the pipelines would be fully operational.^[9], but was soon revised that out to January 2007.^[11] London brent crude hit an intra-day high of $77.73/barrel, the all-time high being $78.18/barrel. United States crude oil peaked at $76.67/barrel. The State of Alaska, which gets most of its revenue from taxing the oil industry may lose as much as $6.4 million each day until production restarts.^[12]

No part of the Alaska Pipeline was affected, although Alyeska said that lower crude oil volumes could slow pumping during the BP shutdown.^[13]

The field has since reopened, however, in mid-June 2007, a small leak occurred in one of the pipelines that connect the field to the Trans-Alaska Pipeline, shutting down the field for a week.^[14]

[edit] References

[edit] External links

• Prudhoe Bay History - at Columbia University

Coordinates: 70°18′24″N 148°43′57″W / 70.30667, -148.7325