Tullow Oil said today it had made a significant gas discovery in the North Sea but had less luck drilling in Equatorial Guinea.
"The K4 exploration well... has encountered reservoir quality gas bearing sands in the targeted lower ketch carboniferous interval and significant upside potential has been identified," Tullow said in a statement.
Dealers saw Tullow's London-listed shares gaining 6 pence from their closing price on Thursday of 320-1/2 pence.
"The success of K4 also provides further encouragement for the remaining exploration potential of this area," Tullow said of its joint venture with ConocoPhillips and GDF Britain.
But test drilling in May at its deep water Banyan exploration well in offshore Equatorial Guinea has not encountered hydrocarbons, it added.