San Leon Energy launched a share buy back of up to $30m by way of a tender offer.
The company offered to buy back its shares at 46p each, representing a 50% premium to their closing price on Tuesday.
'We are delighted to be able to announce this tender offer, which is considerably larger than previously announced,' chief executive officer Oisin Fanning said.
'The scale of the tender offer reflects our strong financial position, our confidence in the company's future prospects and commensurate cashflow, and our view that the current share price does not reflect fully the potential value of our business.'
'We will continue to seek opportunities to return capital to shareholders through either further share buyback tenders or dividends, as the business continues to grow and we execute our strategy on the ground in Nigeria.'