It is America's largest oilfield, with a strategic importance that is tremendous but an environmental effect that has not been gauged.

The shares continued to climb in excitement over the potential of a large Colombian oilfield discovered earlier this year.

A large Colombian oilfield, with reserves estimated at 1.5 billion barrels, may be the nation's biggest economic bonanza.

Al-Safaniya, the world's largest offshore oilfield is in the Persian Gulf.

Venezuela is improving its oil quality by deeper drilling from a large new oilfield in the eastern part of the country.

Daqing's oilfield is China's largest oilfield, and the world's fourth most productive oil field.

It is the largest oilfield exploited by Denmark.

Subcommittee members accused the executives of systematic neglect, leading to the short-term closing last month of the nation's largest oilfield.

Drumright and nearby Cushing were at the center of a large, productive oilfield in the 1910s and 1920s.

By comparison, China's largest oilfield, at Daqing, produces more than a million barrels a day.