A $100 million seismic and $300 million infill drilling program, based around the Kingfish, Bream, Halibut and Fortescue fields, is adding 30,000 barrels of crude oil to the partners’ daily production, Nolan said on the weekend.

This means the natural decline curve for production has flattened, with total liquids production averaging 127,000 barrels a day in 2006.

In April, Nolan said he was confident production could be boosted to reach up to 140,000bpd.

The ExxonMobil-BHP Bass Strait assets produced more than 500,000 barrels a day of liquids in their heyday, but until this program began they were experiencing natural decline of 20% per annum.

Nolan said the recent turnaround in production decline was thanks to improvements in technology, particularly in processing seismic data and drilling accuracy.

"As a result we have been able to more precisely firm up targets and go back over older areas to identify and extract more oil," Nolan said.

This meant the Kingfish field, which has already produced more than 1 billion barrels of crude, was expected to keep producing until 2025, 10 years longer than the original estimate of 2015.