West Africa-focused oil and gas group Bowleven has made a big discovery off Cameroon.The firm said it has come across "11 metres of independently assessed net hydrocarbon pay intersected within upper part of Deep Omicron interval" at the Sapele-3 exploration well drilling in the Douala Basin.The shares jumped nearly 40% to 103.5p after the announcement."We are excited with results so far at Sapele-3," said Bowleven chief executive Kevin Hart. "The Deep Omicron interval continues to deliver and the confirmed presence of oil and good quality reservoir at this location further emphasises the significance of this play within the Douala Basin."Edinburgh-based Bowleven has interests in Cameroon and Gabon.---RG