Increased production at its oil fields in Ghana, higher oil prices and lower costs helped Tullow Oil build up its free cash flow position and significantly reduce debt in 2017.
Tullow said in a trading statement on Wednesday that it expected to have generated $500m in free cash flow, exceeding its forecast at the start of the year, thanks to "strong production, rigorous cost discipline and a rising oil price".
The company said it expected to report revenue of $1.7bn for the full year and gross profit of $800m.
"Tullow delivered strong operational and financial performance in 2017 against the backdrop of continued industry volatility," said Paul McDade, chief executive.
There was also improvement in the company's balance sheet as it reduced net debt by $1.3bn.
McDade added: "Over 2018 we expect to continue this positive momentum. With our diverse low-cost assets and high-graded exploration portfolio, enhanced by recent licence additions in Côte d'Ivoire and Peru, we have a strong foundation to grow the business and further reduce our debt."
Shares in Tullow rose 0.23% to 221.8p in early trade on the London Stock Exchange.