The oil giant said three discoveries at its exploration project 250 miles southwest of New Orleans have the combined potential for more than 700 million barrels of recoverable oil and gas equivalent.
He noted that there are some deep-water wells of significant size in the region, including Chevron Corp.'s Tahiti project with an estimated total recoverable resources of 400 million to 500 million barrels of oil and gas equivalent.
BP has a stake in a number of wells such as the Tiber project which is expected to be one of the largest discoveries in the U.S. Weiss said BP hasn't announced how much it will be able to recover yet.
BP also operates Thunder Horse, a deep-water well designed to process 250,000 barrels of oil per day.
Exxon's announcement makes it the first company to discover oil from a new deep-water well in the Gulf of Mexico since last year's massive oil spill.
The company adjusted its drilling plan to meet new federal guidelines and regulators approved its permit on March 22.
The latest well was drilled in 7,000 feet of water and is continuing to explore deeper.
Steve Greenlee, president of ExxonMobil Exploration Co., said more than 700 million barrels of oil equivalent could be tapped by underwater wells in the region.
In May, Noble Energy Inc. announced it had discovered oil as part of a continuing drilling operation in the Gulf.
Exxon is the operator and majority owner of the Keathley Canyon well. Eni Petroleum US and Petrobras America Inc. hold minority stakes in the operation.