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The oil and natural gas production companies BP Plc, Andarko Petroleum Corp and BHP Billiton have all shut down and evacuated employees at their offshore drilling sites, according to The Chicago Tribune.

BHP Billiton

The company BHP Billiton is reported to have evacuated all of their employees from their oil and natural gas drilling platforms in the Gulf on Friday.

The Shenzi and Neptune platforms can produce about 17,000 barrels per day (bpd) of oil and 100 million cubic feet per day of natural gas.

Andarko Petroleum Corporation

Andarko Petroleum Corporation is the largest produce of natural gas in Gulf. The company began evacuations at four of eight sights on Saturday.

The Andarko Independence Hub is one of the four platforms that have been shut down. The natural gas drilling platform is able to produce as much as a billion cubic feet of gas a day.

The Marco Polo, Constitution and Neptune platforms in conjunction with the Independence Hub are able to produce up to 204,000 bpd of oil and 1.5 billion cubic feet per day of natural gas.

BP Plc

BP Plc is reported to be the largest producer of oil in the Gulf. They shut down and evacuated seven platforms late Saturday evening.

The employees who are not able to evacuate will remain and shelter on site during the storm.

Their Thunder Horse deep water platform is one of the sites that is currently shut down. The site, which is the world's largest deep water platform, can produce 250,000 bpd of oil and 200 million cubic feet of natural gas per day.

Effects on Production

While operations in the Gulf of Mexico are responsible for the production of 20 percent of the U.S. oil supply and 6 percent of the U.S. natural gas output the impact to for U.S. production is not expected to be extreme.

Overall, about 7.8 percent of the daily oil output and about 8.16 percent of the daily natural gas output have been shut down by Tropical Storm Debby as of Sunday afternoon.

Deep water drilling platforms operated by Chevron Corporation, Apache Corporation and ConocoPhillips are still operating.

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