A group led by Chevron Corp. has discovered what it calls "a second giant oil field" in waters off Angola, the San Francisco-based company said. Tests from a well drilled at the new field yielded results similar to those the group had gotten from the nearby Kuito field, which company officials and analysts say may hold as much as 1 billion barrels of recoverable oil, or about a quarter as much oil as is in the North Sea's largest oil field. Angolan oil production, at 710,000 barrels a day in 1997, is set to increase 13% to 800,000 barrels a day this year, the U.S. Energy Information Administration said. In 1996, Angola was the sixth-largest supplier of crude oil to the United States. Chevron shares fell $2.25 to close at $75.81 on the NYSE.