Key Highlights

• Bunian-6 encountered an interpreted oil-bearing interval within the target reservoir section.

• The result is based on well information and does not yet establish a sustained production rate.

• Testing and completion work will determine reservoir quality and commercial deliverability.

• The well forms part of Bass Oil’s programme to lift output from its Indonesian assets.

Wireline logs rarely make headlines, but those run at the bottom of Bass Oil (ASX:BAS)'s Bunian 6 well in South Sumatra handed the small Australian producer something unbudgeted: a third oil-bearing reservoir.

In an announcement lodged with the ASX in early September, the company said the well intersected oil pay in the TRM3 and K1 sandstones, as its pre-drill model predicted, then found a further oil-bearing interval in the M sand at the base of the hole. The M sand has not previously been intersected in the Bunian field, Bass said, although it is a primary producing reservoir in the neighbouring Tangai field.

Managing director Tino Guglielmo called the M sand result a welcome Bonus that should positively affect field oil recoveries. What the announcement did not do was put a flow rate, or a reserve figure, on it.

Logged, not yet tested

That distinction matters. An oil zone identified on logs is an interpretation of the rock's properties, not oil flowing to surface at a measured rate, and a further step again from a booked reserve. Bass said the M sand's reserves impact would be quantified only after further analysis and well testing.

The rig was completing Bunian 6 as a tandem producer from all three reservoirs, with the well expected online shortly after the rig moves off location. Until perforation and testing results are reported, the newly logged zone's contribution remains an estimate, not a measured outcome.

What the well is meant to do

Bunian 6 was spudded on 5 June 2026 and drilled towards a planned total depth of about 1,820 metres, reaching 1,573 metres on 21 August. The primary TRM3 objective alone was forecast to deliver roughly 500 barrels a day.

On the company's numbers, the well should lift Tangai-Sukananti production from roughly 250 barrels a day to about 750 on a 100 per cent basis, taking Bass Oil's share from about 140 to roughly 410. Bass operates with a 55 per cent interest, Mega Adhyaksa Pratama Sukananti holding the balance.

The Indonesian contract that makes it work

The asset sits under a kerja sama operasi, or KSO, with Indonesian state-owned Pertamina EP. Bass secured a 10-year extension in August 2023 running the term to 16 September 2035, and said the renewed terms replaced a fixed 15 per cent after-tax profit split, less domestic market obligations, with a sliding scale to 35 per cent and no obligation.

The structure also shapes the Economics of the well. Bass has repeatedly said Bunian 6 drilling expenditure is fully cost-recoverable against existing production under the KSO, limiting the cash outlay for a company that reported A$0.92 million in cash at end-2025 and announced A$3.0 million of Placement commitments in March 2026.

Scale, price exposure and what comes next

Bass Oil remains small. It reported June production of 225 barrels a day across the group, 141 from Indonesia and 84 from the Cooper Basin, and net sales of A$561,477 for the month. Indonesian crude realised US$77.48 a barrel while Cooper Basin oil fetched an average A$116.58, leaving Earnings exposed to the oil price and the Australian dollar.

The company is also pushing into gas. It completed the Vanessa gas field Acquisition in mid-June, gaining a processing plant and a five-kilometre pipeline into existing Cooper Basin infrastructure, and says it is targeting first gas sales around year end.

The confirmed near-term milestones are narrow: bringing Bunian 6 online once the rig demobilises, reporting actual production from the completed well, and the testing that will determine whether the M sand changes field reserves. None had been reported as at 8 September 2026, and the 80 per cent chance of success quoted before drilling was a probability, not a result. Investors have the logs; the flow rates come later.