One train could be built at the ExxonMobil-led PNG LNG location, and up to two trains could be derived from the Elk-Antelope resource, Oil Search's managing director Peter Botten said today at an investor briefing.

For an expansion of PNG LNG, the feedstock gas would most likely come from the P'nyang area operated by ExxonMobil, while the Elk-Antelope fields would feed the Gulf LNG project.

There are still many details to be finalised, but Oil Search said it is targeting final investment decisions by the end of 2016, with progressive delivery of additional trains from 2019 to 2022.

Train sizing and start-up dates would be dependent on the level of co-operation between the various resource owners.

"Oil Search is uniquely positioned over the next 12 months to drive an optimal LNG development plan in PNG through promoting a co-operation agenda," said Botten.

"Approximately US$3 billion of potential capital cost savings and about two years production acceleration could be achieved through co-ordinated development."