Statoil, working with Exxon Mobil, announced workers encountered indications of natural gas in a 2,100-square-mile block off Tanzania. Work began in January in a well 8,400 feet below the water's surface.
Statoil described the reserve as "a good quality reservoir," adding it's expected to take around three months to complete the drilling operation.
The company said it's too early to give an indication of the size or commercial prospects of the discovery. A final assessment would come once drilling operations are completed.
The World Bank announced last year it approved an International Development Association credit of $27.8 million to back Tanzania's energy expansion projects. U.S. officials had said a lack of energy is one of the main reasons for slow development in the region.