JPMorgan is running the sales process for PTT and that a billion-dollar stake of the estimated $2 billion Montara project is on the market, with the operation expected to hit peak production this year, The Australian reports.

The value of the Cash Maple fields, located further north and toward WA's maritime boundary, is less clear - with PTT recognising it needed billions of investment and considering floating LNG options with a final investment decision scheduled for 2015.

Planned Montara development is targeting 30,000 barrels per day of oil production and first oil was achieved in June.

This milestone came almost four years after one of Australia's worst oil spills at the site. In that blowout-triggered disaster, the West Atlas rig was gutted by fire when the leak ignited on November 2, 2009, amid attempts to plug the leaking H1 well.

Its remains were towed to Singapore and scrapped.

PTT was issued $510,000 of fines and suffered the embarrassment of some damning findings from an inquiry into the disaster.