Shell announced Wednesday it made a substantial discovery of natural gas in the deep waters off the coast of the West African nation of Gabon.

The company said it ran into a 656-net foot column of natural gas in its Leapord-1 frontier exploration well off the Gabonese coast. The well was drilled in water more than a mile deep into a basin trapped beneath a deep layer of submarine salt.

"Shell and partners [at China National Offshore Oil Corp.] are planning to undertake an appraisal program to further determine the resource volumes," the company said in a statement.

Gabon's geological similarities to Brazil raised hopes for oil production among energy explorers, but so far the region has turned up mostly natural gas.

Italian energy company Eni and Australian major Woodside Petroleum are among the more active players in a re-emerging Gabonese energy sector.

Shell said it's been exploring off the Gabonese coast for more than 50 years.