PT Hess Indonesia said it believed it has found a huge gas reserve in the Semai V field in the Arafuru sea off Papua.
The Semai V field may hold gas reserve as big as that of Tangguh, Hess operation superintendent Joseph Witjaksono said.
The Tagguh gas field in the Bintuni Bay of Papua has a reserve of 14 trillion cubic feet, the country's largest gas reserve being operated by BP.
Witjaksono said geological basin in Semai is similar to that of the Tanggug block indicating the reserve could be the same in size.
He said Hess Indonesia will soon carry out feasibility study to determine the proven reserve of the block.
Hess was awarded the block through a tender defeating a number of other major bidders including Shell, Total, Inpex, Marathon and Exxon as well as state oil company PT Pertamina.
Hess plans to spend US $143 million for explorations in three years and paid US $40 million bonus to the government, the newspaper Investor Daily said.