Norwegian oil and gas company Statoil ASA (STO) Monday said it has made a significant oil discovery in the North Sea with Norwegian state-owned Petoro AS , Det Norske Oljeselskap ASA (DETNOR.OS) and Lundin Norway AS, the Norwegian arm of Sweden 's Lundin Petroleum (LUPE.SK).

Statoil said a 65-meter oil column was found on the Aldous Major South prospect, and data confirms the reservoir is of excellent quality.

Preliminary volumes are estimated to be between 200 and 400 million barrels of oil equivalent for this part of the structure in the license and the firm expects additional gains in the license, both north and south of the discovery.

The company said the discovery suggests a link with the Avaldsnes discovery, where a 17-meter oil column has been discovered.

"Aldous Major South is a considerable oil discovery in one of Statoil's core areas. Together with the Avaldsnes discovery this may allow for a new stand-alone development in the
North Sea ," said Gro G. Haatvedt, Statoil's senior vice president for exploration on the Norwegian continental shelf.

The discovery announced Monday follows the announcement in April of Skrugard, a major oil find in the
Barents Sea . Its volumes are estimated at 250 million barrels of oil equivalent, but Statoil has said it could hold as much as 500 million barrels of oil equivalent.

The finds are welcome news to Statoil which has struggled with falling output. The company, which is 67% owned by the Norwegian state, posted a 16% drop in production in the second quarter due to maintenance and unplanned outages, following incidents such as gas leaks.

The company has said it is looking to invest $16 billion this year and about the same amount next year to boost its output.

Statoil owns 40% of Aldous Major South, while Petoro owns 30%, Det norske oljeselskap 20% and Lundin
Norway 10%. Statoil's stake in the Avaldsnes discovery is also 40%.

Det Norske Oljeselskap got a boost from the announcement of the Aldous find and was trading 13% higher at NOK28.10. Analyst Teodor Sveen Nilsen at First Securities said the oil discovery is important news for the firm and noted its shares also get support Monday from the news of a gas discovery on the Norvarg prospect in the
Barents Sea .

At 0857 GMT Statoil shares traded 0.3% higher at NOK119.10.