The news came in an update on progress at Ithaca's Greater Stella area project, which highlighted potential for firms to develop significant new fields in the mature North Sea.
Ithaca said the first well drilled to develop the Greater Stella fields off eastern Scotland flowed at 10,835 barrels oil equivalent daily. Analysts at Mirabaud Securities called it an impressive rate.
With three more wells to drill, the results raise the possibility the fields may produce at much more than the expected 30,000 boed.
Aberdeen-based Ithaca is on course to complete the project on time and on budget. It is investing $385m (£245m) in Greater Stella, due onstream next summer.
"This is an enormous leap forward in de-risking of the Greater Stella Area development and the creation of a major new production hub in the UK Central North Sea," said chief executive Ian McKendrick.
The results provided a big boost for Ithaca Energy, which has ambitions to become a major player in the North Sea. The company significantly increased its exposure to the area through the £203m acquisition of Valiant Petroleum in March.
Production from the Greater Stella fields could generate lots of cash Ithaca could use to grow its North Sea portfolio.
The Aim-listed company says it aims to realise the value of 30 million barrels reserves thorough its investment.
Analysts at joint house broker RBC Capital Markets said the Greater Stella project is central to the company's outlook.
While Ithaca still has lots of work to complete on the development, the results to date are likely to be welcomed by champions of the UK North Sea.
Ithaca is one of a range of companies that are investing heavily in bringing undeveloped discoveries onstream in UK waters.
Strong increases in oil prices in recent years combined with advances in technology have helped transform the economics of some fields that have lain undeveloped for years.
Ithaca and Holland's Dyas acquired interests in the Stella and Harrier licence through deals with Shell, Esso and Maersk between 2008 and 2009.
Ithaca has noted there are other undeveloped discoveries surrounding the production hub that is being constructed for the Greater Stella fields.
Shares in Ithaca Energy closed up 18.25p at 144.75p.
Ithaca has a 54.66% stake in Greater Stella, Dyas has 25.34% while Petrofac has 20%.