Empyrean farmed into the Duyung PSC earlier this year following its exit from the Sugarloaf Eagle Ford Shale play, initially taking a 20% interest.
However, the company amended the deal late last month to maintain an interest at 10% for a payment of $US2 million towards the well.
Duyung PSC sits in the Natuna Sea in water depths of 60-100m, and the block is close to the West Natuna Transport System, with both gas export and oil production facilities located nearby.
The Mako shallow gas discovery is estimated to contain between 400 billion cubic feet to 1.3 trillion cubic feet of gas-in-place.
Three previous wells drilled at Mako between the 1970s and 1990s intersected the gas zones but were not flow tested. Two of the wells were targeting deeper oil and the third well, targeting gas, encountered technical difficulties as was not tested.
Mako South-1 is expected to spud soon and will target the IntraMuda sands.
The objective of the well is to flow test the gas sands and provide key data on the permeability and gas saturation properties of the reservoir.
The well will be drilled with the COSL Seeker jack-up drilling rig, which headed under tow to its offshore location a week ago.
Empyrean expects to spend $2.65 million for drilling and testing the prospect.
The company, which has also signed up to participate at 25% in the significant Dempsey-1 well, within California's Sacramento Basin, also announced a further raising of £300,000 ($A507,000) last week, to bring its total capital raising to £862,800,
Empyrean has also indicated it has started permitting for a 500sq.km 3D seismic program within Block 29/11 (100%), in the Pearl River Mouth Basin, offshore China.
The Chinese permit was secured last year from CNOOC and is south of a large producing field.
There are two defined prospects, Jade and Topaz that will be the focus of the survey, which is expected to begin before the end of the month.
The Singapore-based Conrad is headed up by two Australians, former Pryme Energy CEO Justin Pettit and former Mubadala Petroleum and Woodside Petroleum executive David Johnson.