Key Highlights

• Bunian 6 has confirmed a new oil discovery in the M sand, a reservoir not previously produced in the Bunian field, flowing at approximately 2,400 bopd on a one-hour clean-up with no water.

• A subsequent three-hour flow test on the M zone at a reduced choke of 10.5mm produced 1,264 bopd at a flowing pressure of 415 psi, recovering an additional 158 barrels of oil with no water.

• The well has been completed as an oil producer from three pay zones — TRM3, K1, and M — and is expected to increase field production from 250 bopd to at least 750 bopd (100% share).

• BAS shares traded at A$0.069, up 9.52% on the day of the announcement.

Bass Oil Limited (ASX:BAS), an Australian-listed oil producer with Assets in the Cooper Basin and a 55% operated interest in the Tangai-Sukananti KSO in Indonesia, has announced the confirmation of a new oil discovery in the M sand at the Bunian 6 development well. The announcement, released on 9 September 2026, reports that the M sand — identified as a new pay zone during wireline logging and mud log analysis — flowed oil during a clean-up phase at a rate of approximately 2,400 barrels of oil per day (bopd), recovering 100 barrels of oil in one hour on a 23.9mm choke with no water production.

Oil pay in the M sand has not previously been intersected or produced from this zone within the Bunian field. However, Bass has noted that the M sand is the primary producing horizon in the adjacent Tangai oil field, providing a geological analogue for the potential productivity of the new pay zone. The flowing wellhead pressure during the clean-up phase fluctuated between 210 psi and 395 psi, and a shut-in pressure of 560 psi was recorded after 30 minutes of shut-in.

Production Test Results and Reservoir Parameters

Following the initial clean-up flow, a production test was initiated on the M zone using a reduced choke of 10.5mm. Over a three-hour flow period, the M zone produced 1,264 bopd at a flowing pressure of 415 psi, recovering an additional 158 barrels of oil with no water. The well was then shut-in to observe the pressure build-up, which will be used to characterise reservoir permeability and skin parameters. These reservoir parameters will be used to inform the selection of the zone to be put on production first from the three confirmed pay zones in the well: the TRM3, K1, and M reservoirs.

The well was completed by the rig as an oil producer from all three pay zones — TRM3, K1, and M — with the completion configured to allow each zone to be tested and produced separately. The rig was released at 4:00pm local time on 7 September 2026. A wireline unit subsequently moved onto location to perform swabbing operations to initiate production, and flowline tie-in to the production Facility was underway at the time of the announcement.

Projected Production Impact and Existing Field Output

Bass Oil has indicated that Bunian 6 is expected to increase production at the Tangai-Sukananti KSO from its current level of 250 bopd to at least 750 bopd, representing a threefold increase on a 100% joint venture basis. On a Bass-only 55% interest basis, this equates to an increase from approximately 140 bopd to approximately 410 bopd. The company has stated that the initial production from the TRM3 zone is forecast to be 500 bopd, followed by sequential production from the K1 and M reservoirs. Based on internal modelling, the Bunian 6 well has an expected initial production rate of 500 bopd and an estimated ultimate recovery of 151,000 barrels of oil on a P50, 100% joint venture share basis from the TRM3 zone. The company has cautioned that actual results may differ and are subject to drilling, completion, and reservoir performance outcomes.

Geological Context and Future Development Targets

Bunian 6 was identified as a development drilling target through an integrated field study that included reprocessing of the Sukananti 3D seismic survey and advanced seismic attribute analysis. The study has also identified additional drill targets within the Bunian structure, including Bunian West and Bunian North West. The Bunian field contains oil at three reservoir levels, and Bunian 6 was positioned near the CREST of the structure to optimise drainage of the oil accumulation.

The Tangai-Sukananti KSO is operated by Bass Oil Sukananti Ltd with a 55% interest, with Mega Adhyaksa Pratama Sukananti Ltd (MAPS) holding the remaining 45%. The impact of the M sand discovery on field reserves will be quantified following further analysis of data acquired during the evaluation and testing program.

Share Price Performance

On 9 September 2026, Bass Oil (ASX:BAS) shares were trading at A$0.069, up A$0.0060 or 9.52% on the day at 10:51 am GMT+10, reflecting the market's response to the Bunian 6 M sand oil discovery announcement.

Conclusion

Bass Oil's Bunian 6 well has confirmed a new oil discovery in the M sand, adding a third pay zone to a well that had already been expected to produce from the TRM3 and K1 reservoirs. The M sand flowed approximately 2,400 bopd on a short clean-up and 1,264 bopd over a three-hour test at a reduced choke, with no water production recorded in either flow period. The well has been completed as an oil producer from all three pay zones, and Bass has projected a minimum threefold increase in field production from the Tangai-Sukananti KSO once the well is on sustained production. The financial impact on reserves and production guidance will be updated following full analysis of the test data.