In mid-April BHP Billiton group energy president Philip Aiken told delegates at the Australian Petroleum Production & Exploration Association (APPEA) conference in Perth that BHP saw the Scarborough gas field and the proposed $5 billion Pilbara liquefied natural gas project at Onslow, Western Australia as priorities.

Aiken said three recent appraisal wells drilled by BHP had increased certainty about the field, which it estimated to contain 8 trillion cubic feet of gas.

Now BHP's Pilbara LNG vice-president, Neil Croker, has told the West Australian Power and Gas conference held in Perth last week that BHP would not rule out buying ExxonMobil's stake in Scarborough in order to advance the project.

But ExxonMobil has said it does not intend to enter negotiations with BHP about the field. While the Scarborough field is held 50/50 by the two partners, ExxonMobil is the operator and the field cannot be developed without its agreement.

Speaking at the APPEA conference ExxonMobil Australia chairman Mark Nolan questioned BHP's conclusions about the Scarborough field.

"ExxonMobil believes Scarborough is unlikely to be commercially viable in the near term," Nolan said.

"BHP's assessment [of reserves] is very high and we don't agree."