Afren said it encountered oil at prospecting lease 310 off the coast of Nigeria. It said the results from the exploratory drilling operation were "significantly" better than it expected.
The company said Tuesday it drilled its Ogo-1 well to a total depth of 10,518 feet and encountered an oil layer measuring 524 feet thick. Based on that data, the company said it expected the prospect holds at least 774 million barrels of oil equivalent.
Afren, headquartered in London, said the Ogo prospect represented a wildcat opportunity, meaning it was located in an area not proven to hold oil reserves, in an underexplored area off the Nigerian coast. It said preliminary data show there may be "several prospects" in the same area that have the same characteristics as major discoveries found off Ghana and Ivory Coast.
Nigeria's oil sector has been handicapped by sabotage, rebel activity and environmental damage.
Nigeria is a member of the Organization of Petroleum Exporting Countries. OPEC in its latest monthly report said Nigeria produced 1.8 million barrels of oil per day in October.