Tullow Oil said today that it would look to raise £607million through the sale of more than 450million new shares.
Tullow said the rights issue was subject to shareholder approval and would be fully underwritten by Barclays Bank.
The firm, which has interests in more than 100 exploration and production licences across 18 countries, expects the admission to go ahead on April 6.
Tullow’s shares are listed on the London, Irish and Ghanaian Stock Exchanges.
Tullow chief executive Aidan Heavey said: “Tullow and its staff have worked exceptionally hard over the past three years to re-set the business comprehensively in the face of the toughest conditions I have known in the oil sector.
“This is the right time to get our balance sheet in order and this offering will give … the management team the necessary financial and operational flexibility to grow our business even if oil prices remain low.”
Since crude prices collapsed in 2014, Tullow has almost halved its headcount and is on course to generate savings of about £485million by mid-2018.
It has also shifted its exploration strategy and sold non-core assets in Mauritania and Namibia.
Its net debt at the end of 2016 was almost £4billion.