Italian energy company Eni said Thursday it made a significant oil discovery at a basin off the western coast of the Congolese republic.

In the Minsala Marine shallow-water prospect, the company said it found about 1 billion barrels of oil equivalent, of which 80 percent exists as oil.

The prospects were enough to start preparations for commercial development of the well, the company said.

"These discoveries are located in conventional waters near existing infrastructure and can therefore be brought into production in very competitive time to market and cost," Chief Executive Officer Claudio Descalzi said in a statement.

Reserves off the West African coast are similar to those in Brazil in that they're located beneath a thick layer of submarine salt. Eni said it's already discovered about 4 billion barrels of oil in basins off the Congolese and Gabonese coasts since it started work there more than four years ago.

Eni has been operating in Congo since the late 1960s, producing around 100,000 barrels of oil per day.

For third quarter 2014, the Italian company reported a net profit of $1.48 billion, up 2.5 percent year-on-year.

Oil and gas production for the company was stable from third quarter 2013 at 1.58 million barrels of oil equivalent.