A happy conclusion to drilling at its King Lear exploration well in the North Sea has helped Statoil of Norway maintain confidence in raising its overall output levels by half a million barrels a day by the end of the decade.

Helge Lund, chief executive, said a combination of increased exploration spending and a rejigging of assets had kept Statoil on track for lifting daily production from 1.9m barrels of oil equivalent per day in 2010 to 2.5m boed by 2020.

Earlier this month the state-controlled oil company said it had made a significant gas and condensate discovery in the King Lear prospect in the southern part of the Norwegian North Sea along with its partner Total.

The company is also pushing to explore fields in the Arctic waters of the Barents Sea in both Norwegian and Russian zones following a deal struck with Russian oil major Rosneft as it increases investment in upstream activities.

In June the company also announced further exploration success in Tanzania alongside partner ExxonMobil and also set out its ambitions to triple output in North America by the end of the decade as it emerged as the second-largest spender on new leases in the Gulf of Mexico in the auction held by the federal government. Last year it paid $4.4bn for Texas-based Brigham Exploration.

Mr Lund said Statoil had managed to raise its proven reserve base by as much in the six months to June than in the whole of last year.

“East Africa seems to hold prolific potential from the oil and gas point of view,” he said. He cautioned however that “these are limited areas in terms of their industrial framework to develop oil and gas”.

Shares in Statoil, up 6 per cent over the past year, rose by NKr3 to NKr144 as it delivered results largely in line with analysts’ expectations.

The Oslo-listed company, which has a 29 per cent free float, saw interim revenues rise from NKr112bn to NKr120bn ($20bn). But net income slipped slightly from NKr43bn to NKr42bn.

During the period, Statoil benefited from a NKr7.5bn gain on the sale assets in the Norwegian sector of the North Sea to Centrica of the UK as well as the disposal of its retail operations for NKr8.3bn.