Under the new terms, the conditional agreement covered the sale of gas over a period of 20 years from project start-up, according to Papua New Guinea Gas Project operator ExxonMobil.
Total quantities will now be up to 30 petajoules per year, a substantial increase on the previously agreed 12-20PJ per year.
This increases the best case scenario for contracts to 130PJ per year. The pipeline must still secure another 50PJ per annum to justify its development, but managing director of pipleine partner Oil Search, Peter Botten, said he was confident more buyers would come forward.
"Although this remains a conditional agreement, it is encouraging that volumes committed to the project continue to grow," Oil Search managing director Peter Botten said.
"This attests to the attractiveness of terms offered and a building demand for a new gas supply for eastern and southern Australia."
The gas will be supplied to Olympic Dam for liquid fuel replacement and gas-fired power generation.
The sale remains subject to successful feasibility studies by WMC, according to ExxonMobil.
The PNG Gas Project Owners are ExxonMobil (whose subsidiary Esso Highlands Limited is project operator), Oil Search, MRDC (a PNG company representing landowner interests) and Nippon Oil Exploration Limited.
