North Sea-focused Valiant generated revenue of $233m (£153.5m) for the year ended December 31, 2012, down from $318m (£209.5m) in 2011, after running into delays bringing the Causeway field into production.
Valiant said costs linked to the development were reflected in a $45m (£29.6m) impairment in the accounts. Combined with an exploration write-down of $84m (£55m), Valiant returned what it described as a "small profit for the year".
Chairman Kevin Lyon and acting chief executive Michael Bonte-Friedheim said: "In October, Valiant safely delivered its first operated development in Causeway. Valiant is now a full-fledged operator of production.
"The amount and complexity of work required to achieve this status should not be underestimated."
Mr Lyon and Mr Bonte-Friedheim also underlined that the company was backing its £203m takeover by Ithica.
Valiant shares closed down 3.75p at 450.25p.