Tullow Oil, the London-based explorer, has had a good week: two days after reporting soaring profits it confirmed that an oil strike off the coast of Ghana was a major find.

The Africa-focused company, which has been built from scratch by Irishman Aidan Heavey, has been ramping up a new field in Ghana, where a well has discovered oil in "very good quality sandstone reservoirs". The latest discovery "confirms the significant extent of the Enyenra light oil field".

Tullow was the second biggest riser on the FTSE 100 on Friday morning, with its shares rising 3.67% to £15.25.

Further work will now be undertaken to refine estimates of oil in place.

"This bold step out is an excellent result which is further enhanced by the quality and thickness of the reservoirs found," said Angus McCoss, exploration director. He said the find was "a significant achievement which was only possible through the use of highly refined geophysical techniques".

Rob Mundy at Liberum Capital said: "Whilst this is an encouraging announcement we already have this field in our net asset value and won't be changing our numbers at this stage."

On Wednesday, Tullow doubled its dividend to 8p a share after net income jumped to $665.9m (£422m) last year from $49.2m in 2010. Oil and gas production climbed 35% to an average of 78,200 barrels of oil equivalent a day.

Even so, production at the FTSE 100 company's Jubilee field in Ghana was lower than expected and the company said it planned work on the field to improve output this year. It also hopes to start up its Ugandan fields in 2016.