Brazil's National Petroleum Agency says that for the first time, the country's pre-salt oil reserves now account for more than half of its production of oil equivalent.

The agency said on its website Wednesday that Brazil extracted 1.685 million barrels of oil from pre-salt reserves. That was 50.7 percent of the overall production of 3.325 million barrels.

The reserves lie offshore in the Atlantic more than a mile (1.6 kilometers) below the ocean's surface and under an additional 2.5 miles (4 kilometers) of soil and corrosive salt.

According to the agency, Brazil's pre-salt reserves accounted for 40 percent of total production in 2016.