For Statoil (STO), one plus one equaled way more than two Tuesday.

The company has announced that its Aldous and Avaldsnes oil finds are probably part of a single combined oil structure that contains 500 million to 1.2 billion barrels of recoverable oil.

On Aug. 8, Statoil reported that a well drilling at the Aldous Major South prospect had established a common oil and water contact between the Aldous and Avaldsnes oil structures.

This is the Statoil’s third high-impact discovery this year. (A high-impact discovery is one that holds more than 250 million barrels of oil equivalent.)