It said in a statement the new well was around 9 miles (14 km) from the Banyu Urip discovery made in 2001.

"The Kedung Keris discovery will be an important addition to the 450 million barrels of oil expected to be recovered from the Full Field Development at Banyu Urip," said Terry McPhail, the president of Mobil Cepu.

"Its similarity to the other Cepu fields provides confirmation of our exploration strategy on the block, and its proximity to Banyu Urip provides a good opportunity to advance development of this new oil discovery."

The Kedung Keris-1 discovery well was drilled on land to a total depth of 7,032 feet (2,140 metres). The well encountered an oil column of 561 feet (171 meters) in the target carbonate zone, the statement said.

Mobil Cepu Ltd. and Ampolex (Cepu) PTE Ltd., both subsidiaries of ExxonMobil, hold a 45 percent interest in the block, with Pertamina EP Cepu holding 45 percent and the Cepu Block Cooperation Body (BKS) the other 10 percent.