The well, drilled with the Petroserv semi-submersible Catarina in Block 20, was targeting the Baleia structure, the eastern edge of which was intercepted by a probe back in 1996.
The find marks Cobalt's fifth straight discovery in the Kwanza basin after last month's Bicuar, as well as previous hits at Mavinga, Cameia and Lontra.
Initial analysis of Orca suggest a resource potential of between 400 million and 700 million barrels of oil, though Cobalt did not specify how much pay was hit.
