Exxon Mobil has made two big new oil discoveries and a natural gas find in the deepwater Gulf of Mexico, news that underscores the importance of the basin to American crude output.

Oil and gas exploration in the gulf was halted by the United States government last year after the blowout at BP’s Macondo well, and activity in the gulf remains at levels far below those seen before the oil spill.

Exxon estimated the new wells could produce about 700 million barrels of oil equivalent.

“Seven hundred million barrels doesn’t happen very often,” said John White, an analyst at Triple Double Advisors in Houston. “That’s a lot of oil.”

This portion of the deepwater gulf is thought to hold as much as 15 billion barrels of oil. Recent large discoveries there include BP’s Kaskida field, estimated to hold three billion barrels of oil.