Marathon Oil will start drilling at the Pasang Kayu oil and gas block in Indonesia in the second quarter of 2010, a company official said.
Marathon International Petroleum Indonesia general manager John Bates said the Pasang Kayu block holds potential reserves of more than one billion barrels of oil equivalent.
He added that its oil rig will depart from Singapore in early May.
Pasang Kayu block, the majority of which is offshore, covers 1.2 million acres ranging from onshore Sulawesi to water depths of up to 7,200ft.
Marathon International, a unit of US-based Marathon Oil, owns a 70% interest in Pasang Kayu and operates the block.