Hess, which has headquarters in New York, said it encountered 245 net feet of oil pay over two intervals in the Pecan-1 exploration well offshore Ghana.
The West African country is emerging as a regional energy giant given recent developments. British energy explorer Tullow Oil this week announced that it started producing about 16,500 barrels of oil per day from Phase 1A of the offshore Jubilee field.
Hess said it was working on developments to drill further next year in the Ghanaian discovery area in a well about 15 miles away from its latest discovery.
Ghana, through a European development fund, receives $588 million in financial support through 2013. The European Union has invested $582 million in energy programs in West Africa in the last five years.
Parliamentary and presidential elections last week in Ghana were considered free and fair, securing a victory for incumbent President John Mahama. Opposition leaders said they'd challenge the results, however.