Edinburgh-based Cairn Energy has agreed to sell its share of the Sangu gas field off the coast of Bangladesh to the Australian firm Santos.
The oil explorer is already in the process of selling a stake in its Indian unit for $9.6bn (£5.9bn).
The company said it would use the proceeds of the sale to fund exploration in Greenland.
Meanwhile gas and oil explorer Melrose Resources has started producing natural gas from two fields in Bulgaria.
The Edinburgh company is developing the Kaliakra and Kavarna gas fields in the Black Sea.
The Bulgarian government said the supplies could meet about 15% of the country's annual gas demand over the next few years, and would also help reduce household bills and cut costs for industry.
Bulgaria was forced to increase the price of natural gas by almost a quarter in July as the cost of Russian imports went up.
Meanwhile, Cairn Energy said it was hoping to open a producing centre in Greenland and has said it could spend $1.2bn ( £0.7bn) drilling in the Arctic country.
Shares in Cairn have fallen 17% in the last month partly due to the disappointment over the Greenland drilling programme.