Mitra, a new entrant to Australia, has agreed to take Stag from Quadrant Energy and Santos for a fraction of the original offer price from Malaysian oiler Sona, which eventually offered $25 million after its independent expert found that the initial $50 million offer was too high.

Sona's shareholders eventually declined to support that deal and wanted their money back, so Stag's owners have spent the past few weeks looking for someone else to take the producing oil field off their hands.

Enter Mitra, which has assets in Vietnam, Indonesia and the Philippines, and which is only too pleased to take on the responsibility for Stag at a cut-rate price.

The deal, dated July 1, includes adjustments, plus potential contingent payments of up to $15 million, based on planned expansion plans and improvements in the oil price, but it is far below the originally floated valuation of $100 million.

Mitra's low offer sees it paying just $1 per barrel of oil and a mere 50 cents for each 3P barrel, while it values the field's 2P reserves at around $60 million, assuming a $61/bbl oil price in 2018.

Stag has an estimated 10.1 million barrels remaining with probable reserves of 14.6 million, and is producing around 3750bopd from 10 wells, despite having been in production since 1998.

Mitra says it was attracted to Stag by the high levels of production and the near-field potential that could potentially expand the life of the field.

"We are delighted with this very important acquisition of the producing Stag oil field, which puts Mitra on a path of transformation to becoming a leading upstream production operator in the Asia Pacific region," executive chairman Paul Blakeley said.

"This acquisition is cash generative from day one and provides a solid base for future growth.

"It creates the opportunity to demonstrate efficient and safe operating capability, consistent with what the new management team at Mitra have done in the past in Asia Pacific with Talisman Energy, and will leverage these skills to add value through further infill drilling activity, cost reduction and reservoir management.

"This is exactly the type of asset we are looking to invest in with deep value multiples, and we are very excited to be taking this first step towards building a business which takes advantage of the current market in a low oil price environment, with an increasing set of opportunities where we can best leverage our experience."

He said Mitra had already identified cost reduction measures to continue to lower operating costs for the field and it is planning to drill up to eight wells over the next two years: one appraisal pilot and three infill producers in the Stag West area in 2017 and up to three further wells in the Stag East area in 2018.

Mitra will also consider appraisal activities in the undrilled low risk exploration area of Hart and Stag South.

To support the purchase Mitra is conducting a $50 million capital raising, supported by its major shareholders. Of the cash, $20 million will be used to fund the drilling and $10 million will be used for a bank guarantee.

The deal is expected to close in September.

Stag has 3P upside of 18.6MMbbl.