Shares in Premier Oil climbed more than 5pc after a well in which the company has a 30pc stake was found to have “good quality” crude. Investors also snapped up shares in Xcite Energy after the explorer said that its Bentley field in the North Sea contained more oil than they had previously forecast.

The discoveries are a welcome boost to exploration in the North Sea, which is enjoying a revival in production after it peaked in 1999 and then sank into a deep decline.

After increasing its estimate for reserves in the Bentley field to 900m barrels from 555m barrels, Xcite is now seeking a partner to help it start commercially developing the four wells it has.

“We believe now is the right time to bring in a partner,” said Rupert Cole, the chief executive of Xcite, which has hired investment banks Rothschild and Jefferies to help find a partner who will take a stake in the field.

Given the size of the Bentley field, Mr Cole believes it will have to be a major producer such as BP or Royal Dutch Shell.

“We’ve taken the field from being nothing to one of the largest undeveloped fields in the UK,” said Mr Cole.

A wave of investment over the past two years will push production from the North Sea up by a third to 2m barrels a day by 2017, according to a report from accountancy and consultancy firm Deloitte last week. But production still remains below the almost 5m barrels a day peak.

Premier’s find in the North Sea is in the Johan Sverdrup field, which experts say could ultimately be the highest-yielding field off the Norwegian coast in almost forty years. Lundin Petroleum and Statoil are the other owners of the Luno well. Shares in Premier closed up 6.1pc at 385p, while Xcite finished 8.3pc stronger at 118p.