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Bass Oil Limited (ASX:BAS) has temporarily halted drilling at its Bunian 6 well in Indonesia's South Sumatra Basin due to the pending delivery of replacement mud pumps from the drilling contractor. As of 17 July 2026, the well had reached a depth of 1,012 metres. Drilling is anticipated to resume around 24 July, with production expected to start in late August. Upon completion, the well could increase field output from 250 barrels of oil per day to 750 bopd on a 100% basis. This development well is a low-risk expansion within the Tangai-Sukananti KSO, where Bass operates with a 55% interest.
Key Points
- Bass Oil Limited (ASX:BAS) is an Australian oil producer holding majority stakes in fourteen Cooper Basin permits and a 55% operated interest in Indonesia’s South Sumatra Basin KSO.
- Drilling at Bunian 6 was suspended on 17 July 2026 at 1,012 metres depth pending replacement mud pump delivery by the rig contractor.
- Operations are expected to recommence around 24 July, targeting well completion and production startup by late August 2026.
- The well is projected to raise field production from 250 bopd to 750 bopd (100% JV basis), equating to an increase from 140 bopd to 410 bopd on Bass’s 55% share—tripling output.
- Bunian 6 is classified as a low-risk development well with an 80% estimated chance of success, based on internal modelling and nearby well performance.
- All drilling costs are fully recoverable against current production under the KSO agreement, safeguarding Bass’s capital.
- The well targets the primary TRM3 sandstone reservoir with initial production forecast at 500 bopd and an estimated ultimate recovery of 151,000 barrels on a P50 basis.
Temporary Suspension and Current Status of Bunian 6 Drilling
Bass Oil’s Bunian 6 well drilling operations were paused at 0600 hours on 17 July 2026 at a depth of 1,012 metres due to the need for replacement mud pumps. The drilling contractor is responsible for delivering and testing these pumps before drilling can safely continue. Such planned suspensions are common in onshore and offshore drilling campaigns when equipment maintenance or replacement is necessary.
The company expects drilling to resume around 24 July 2026 after successful pump testing. The drilling plan includes extending the intermediate hole section to approximately 1,400 metres, running and setting the 9-5/8" intermediate casing, then drilling to a total depth near 1,820 metres. Post-drilling, logging and completion operations will be conducted before production begins in late August 2026. This timeline targets production commencement roughly six weeks after the suspension.
Significant Production Increase Anticipated from Bunian 6 in South Sumatra Basin
Bunian 6 represents a major development for Bass Oil’s Indonesian operations within the Tangai-Sukananti KSO. Upon completion, field production is expected to rise from 250 barrels per day to 750 bopd on a 100% joint venture basis. For Bass Oil’s 55% operated interest, this translates to an increase from about 140 bopd to 410 bopd, nearly tripling production from this asset.
The well is deemed low-risk, situated in an established producing field with extensive subsurface data and production history. Initial production from the TRM3 sandstone reservoir is forecast at 500 bopd (100% basis). The estimated ultimate recovery stands at 151,000 barrels on a P50 basis, reflecting a well-defined recovery target. Bass Oil estimates an 80% probability of success based on internal models and nearby well data, demonstrating strong confidence in meeting production forecasts.
Overview of Tangai-Sukananti KSO and Geological Context
Located in the prolific South Sumatra Basin, the Tangai-Sukananti KSO includes the Bunian and Tangai oil fields along a major structural trend with large oil accumulations nearby. The Bunian Field, discovered in 1998, is a faulted anticline structure with steady recent production around 250 bopd, supported by established infrastructure.
Bass Oil has conducted comprehensive seismic and geological studies, including 3D seismic coverage and advanced attribute analysis, confirming Bunian 6 as an optimal development site. Additional prospects such as Bunian West and Bunian North West have also been identified, offering future drilling opportunities within the permit area.
Multi-Reservoir Approach in Bunian 6 Well Design
The Bunian 6 well targets multiple reservoirs to maximize economic value. The primary target is the TRM3 sandstone reservoir, with secondary targets including the GRM and K reservoirs, which have shown oil production or testing in nearby wells. This multi-zone strategy enhances capital efficiency and supports long-term field development.
Positioned near the crest of the Bunian structure, the well aims to accelerate oil recovery. Initial production from the TRM3SS is forecast at 500 bopd. Data from the secondary K reservoir will inform future development plans and reserve estimates. This approach leverages the KSO’s cost-recovery provisions while gathering valuable geological and engineering data for future drilling campaigns.
Financial Structure and Cost Recovery for Bunian 6 Development
Drilling costs for Bunian 6 are fully recoverable from existing production under the Tangai-Sukananti KSO agreement. This cost-recovery framework enables Bass Oil to fund development drilling through current cash flows rather than external financing, protecting the company’s capital position.
The KSO joint venture consists of Bass Oil Sukananti Ltd (Operator, 55%) and Mega Adhyaksa Pratama Sukananti Ltd (45%). As operator and majority interest holder, Bass Oil manages the development and drilling activities. The cost-recovery mechanism ensures capital invested in Bunian 6 is recouped from incremental production revenue, supporting shareholder value creation while maintaining a debt-free balance sheet. The anticipated production increase from 250 bopd to 750 bopd significantly boosts cash flow and accelerates recovery of development costs.
Risk Profile and Success Probability for Bunian 6
Bass Oil assigns an 80% probability of success to Bunian 6 based on internal modelling and performance of nearby producing wells. This high confidence level stems from the well’s location in a mature field with established infrastructure and extensive subsurface data.
Nonetheless, actual results may vary due to drilling, completion, and reservoir performance risks. Production forecasts of 500 bopd and an ultimate recovery of 151,000 barrels are model-based estimates subject to operational outcomes. The company confirms no new material information affects current estimates as of the announcement date.
Bass Oil’s Portfolio and Strategic Position in Australia and Indonesia
Bass Oil Limited is an Australian-listed producer with diversified assets including majority interests in fourteen Cooper Basin permits and 100% ownership of the Worrior and Padulla oil fields. In Indonesia, Bass holds a 55% operated interest in the Tangai-Sukananti KSO. The company is also advancing three gas projects and plans to enter the Australian East Coast Gas Market in late 2026, expanding into LNG and natural gas liquids.
Maintaining a debt-free structure, Bass Oil focuses on organic growth from producing assets and development opportunities. Management and the board hold over 10% of issued capital, aligning interests with shareholders. The Bunian 6 project exemplifies this strategy by expanding production capacity, enhancing cash flow, and demonstrating operational capability within a low-risk, cost-recoverable framework.
Production Timeline and Impact on Cash Flow and Field Performance
Drilling at Bunian 6 is expected to resume around 24 July 2026, with well completion and production startup targeted for late August 2026. This six-week timeline reflects the well’s moderate depth (approximately 1,820 metres) and low-risk classification. Initial production of 500 bopd from the TRM3SS will increase field output to 750 bopd (100% basis) or 410 bopd on Bass’s share, significantly boosting cash flow for the remainder of 2026 and into 2027.
The timing aligns with Bass Oil’s broader strategy, including entry into the Australian East Coast Gas Market. Enhanced cash generation from Bunian 6 will support capital programs across Australian and Indonesian assets while preserving a debt-free balance sheet. Additionally, data from the secondary K reservoir target may unlock further development potential. The production uplift, cost-recovery financing, and identified future drilling targets position the Tangai-Sukananti KSO as a key growth asset in Bass Oil’s portfolio.
