Exxonmobil says its landmark Liquefied Natural Gas project in Papua New Guinea is on track to begin production in 2014.
This comes as the oil and gas multi-national announced the estimated project cost has soared from 15.7 billion US dollars to 19 billion.
It says this is due to foreign exchange impacts and delays from work stoppages and land access issues.
One of the causes of lengthy work stoppages this year was January's deadly Tumbi landslide in the Hela region where the project is centred.
The massive landslide blocked the only road access to several key installations.
Access was regained by March but only when the road was rebuilt over the landslide area with the bodies of most of the victims, estimated to number over 20, still buried underneath.
Protests by victims' relatives caused further delays.
Exxon says the construction phase of the project, which stretches across several provinces, is 70 percent complete.