Acquired as part of a largely unsuccessful push to grow the company internationally earlier in the decade, which saw Cooper explore options in Poland, Tunisia and Indonesia, the writing was on the wall for Indonesia as soon as managing director David Maxwell started with the company in 2012.

Preferring to focus on the high margin oil production in the South Australian Cooper Basin and securing a foothold in the east coast gas market, Maxwell quickly dispatched with the Polish assets, and he has long suggested that Indonesia and Tunisia were "non-core".

Tunisia was kept for its appraisal potential in Hammamet West-3, where Cooper drilled a costly well in 2013 with mixed results, while Indonesia's modest oil production was kept in-house as the company advanced the assets, hoping to move them to a sale when the time was right.

And despite the horrid prevailing international oil price, that time is now.

Cooper will pocket $US8.25 million ($A11.67 million) by selling its large earlier stage production sharing contracts, Sumbagsel and Merangin III in the South Sumatra Basin, to Southeast Asian-focused Mandala Energy.

The sale, backdated to January 1, requires government approval and should see Copper pocket more than $10 million at current exchange rates after costs and Indonesian transfer taxes,

Mandala is a junior explorer headed up by the core member of the leadership team responsible for Mubadala Petroleum's success and backed by private equity firm Kohlberg Kravis Roberts & Co.

Cooper will eventually exit Indonesia, and is still negotiating to sell the 55% interest in the highly prospective Tangai-Sukananti licence, where it drilled a successful well last year that boosted production and opened up the potential of block's geology.

"Today's transaction marks another important step in our strategy to concentrate Cooper Energy's resources and efforts on the eastern Australian energy market," Maxwell said.

"Moreover, it will provide timely capital management benefits as we move towards a final investment decision on the Sole gas project".

The benefits from the transaction include the cash and the removal of existing licence commitments for seismic acquisition and the drilling of two wells.

Cooper recently reported cash and investments of $30.2 million at December 31.

Mandala CEO Barry O'Donnell said the acquisition of the two large PSCs was a very important strategic milestone for his company.

"From a portfolio perspective, it significantly increases our footprint in the prolific South Sumatra Basin and provides us with operatorship of two high quality exploration assets," he said.

"We look forward to executing an extensive seismic and drilling program in order to quickly realise the potential of both blocks."

Maxwell said the decision to divest the Indonesian assets was driven by the maturation of the company's eastern Australian gas strategy, and while he put his foot on the gas in December he has made no bones about the fact that Cooper would not be in Indonesia forever.

"Our involvement in Indonesia pre-dates the strategy adopted in 2011 to focus on the opportunities we foresaw in eastern Australian gas supply," he said.

"The Indonesian assets were retained on the strength of the opportunities to add value through geologic studies in Sumbagsel and Merangin III and increasing reserves and production in Sukananti.

"Although we consider the Merangin III and Sumbagsel PSCs to be very prospective, now is the right time for Cooper Energy to realise the value available for its Indonesian portfolio and to increase the focus we bring to our Eastern Australia projects."

The remaining Tangai-Sukananti block, which is producing around 800 barrels of oil per day (gross), could be upgraded to 2000bopd with an increase in processing and transport capacity and conduct development drilling.

The block has 3.1 million barrels of 2P resources.

Cooper has warned it may need to book a $9 million writedown in the carrying values of its Indonesian assets to reflect current valuations when it releases its interim accounts on February 25.

Sumbagsel was secured in 2011 and covers an area of 1753sq.km.

It lies directly north of Sukananti, which hosts three oil fields acquired by Cooper in 2010, and close to Merangin III, which was secured in 2013 and has a $US10 million drilling commitment this year.

Cooper shares dropped 6.06% yesterday to $0.155.