Santos ASX: STO) takes FID on Moomba Central Optimisation project in Cooper Basin

Santos Limited (ASX: STO) has taken a final investment decision (FID) on the Moomba Central Optimisation project in South Australia’s Cooper Basin, committing A$357 million net to a three-year infrastructure overhaul that the company says will generate more than A$600 million in combined capital and operating expenditure savings over the life of the Central Fields. The project, approved jointly with minority joint venture partner Beach Energy (ASX: BPT), will replace seven ageing gas-driven compressor stations with a single electric-driven compressor station, debottlenecking upstream infrastructure and enabling full-field development of the Central Fields area. Santos has fully budgeted the investment within its existing A$45 to A$50 per barrel all-in free cash flow breakeven target, signalling that management considers this a capital-efficient deployment rather than a stretch allocation. The announcement arrives days after Santos executed a Key Term Sheet with the South Australian government to supply 20 petajoules per year from the Cooper Basin from 2030 to 2040, with prepayment funds from that deal intended to partly finance the Moomba Central Optimisation project, subject to finalising a gas supply agreement.

What are the financial returns and payback profile of the Moomba Central Optimisation project, and do they clear Santos hurdle rates?

The project economics are straightforward and, on paper, compelling. Santos is targeting an internal rate of return above 15 per cent at the Moomba Central Optimisation project level, with a payback period of six years. The full-field development that the project is designed to enable carries a projected IRR above 25 per cent, which is a materially stronger return and explains why Santos framed the optimisation investment as the key that unlocks the higher-value Central Fields program rather than a standalone infrastructure spend.

Unit production cost improvement is targeted at up to A$3 per barrel of oil equivalent, driven by the shift from multiple gas-driven compressors to a single electric-driven station. The modernisation also eliminates ongoing maintenance costs and reliability risk across seven separate legacy units. Santos’ guidance that this investment remains within its A$45 to A$50 per barrel breakeven envelope is relevant context: it means the MCO does not require Santos to revise its capital allocation framework or increase its price deck assumptions to justify the commitment.

That said, infrastructure projects of this scale in remote South Australian operating environments carry execution risk. Three-year delivery timelines in the Cooper Basin have historically been sensitive to weather disruptions, labour availability, and equipment supply chains. A significant flood event in the Cooper Basin delayed production in mid-2025, and the region remains exposed to periodic operational disruption. Investors should weight the IRR projections as targets rather than guarantees.

Why is the Cooper Basin Central Fields area strategically important to Santos, and what does its 2P reserve position imply for production growth?

The Central Fields contain more than half of Santos’ remaining proved and probable reserves in the Cooper Basin. That reserve concentration, combined with higher-productivity wells relative to the broader basin, makes the Central Fields the single most consequential development area in Santos’ Cooper Basin portfolio. The Moomba Central Optimisation project is not simply an operational upgrade. It is the enabling infrastructure without which the Central Fields cannot be produced at full capacity.

Santos added 13 million barrels of oil equivalent to its 2P reserves in 2025 before production, with Cooper Basin additions cited as a primary driver. Total 2P reserves reached 1,484 million barrels of oil equivalent at year-end 2025. That reserves life extension underscores the strategic logic of investing in infrastructure now: Santos is growing the inventory it needs long-term production economics to justify, and the MCO project is the mechanism for accessing it.

The Cooper Basin has operated for more than 60 years as a cornerstone of eastern Australian gas supply, connecting through the Moomba Adelaide Pipeline System and downstream infrastructure to South Australian industrial customers, domestic retailers, and LNG processing facilities. Santos is the largest producer in the basin. Any capacity constraint at Moomba flows directly through to available supply in the South Australian and eastern Australian gas markets, which makes the debottlenecking investment relevant not only to Santos shareholders but to downstream industrial buyers planning long-term supply arrangements.

How does the South Australian Strategic Gas Reserve deal connect to the MCO investment and what are the financing implications?

The financing structure here is worth examining carefully. Santos has agreed Key Terms with the South Australian government to supply 20 petajoules per year from 2030 to 2040 for the state’s Strategic Gas Reserve, with an annual contract quantity representing approximately 30 per cent of Santos’ current Cooper Basin gas production. The deal includes a prepayment component that Santos intends to direct toward MCO project funding, subject to concluding a fully formed gas supply agreement by 30 June 2026.

This creates an integrated capital allocation structure: the government deal provides upfront cash that reduces the effective equity outlay for the infrastructure investment, the infrastructure investment unlocks the Central Fields production capacity needed to service the 20 PJ annual supply commitment from 2030, and the long-term offtake agreement provides contracted revenue visibility that supports the capital case. Santos is effectively using a government supply contract as project financing for a basin-scale infrastructure upgrade, which reduces risk on both sides of the arrangement.

The dependency on concluding the gas supply agreement by mid-2026 is a near-term execution variable. If negotiations stall, Santos has stated it will still proceed with the MCO project using fully budgeted capex, but the economics improve materially when the prepayment is available. Investors watching the stock through mid-2026 should monitor the GSA closure as a positive catalyst for cost-of-capital on the project.

What are the competitive dynamics in the Cooper Basin after this FID, and how does Beach Energy’s position factor in?

Beach Energy holds a joint venture interest alongside Santos in the Cooper Basin and was a co-approver of the MCO final investment decision. Beach recently secured three additional exploration blocks in the Cooper Basin alongside Santos, with Beach Chief Executive Brett Woods citing the blocks’ proximity to existing joint venture infrastructure as a key rationale for rapid commercialisation. Beach’s stated strategy of expanding domestic gas supply positions it as an aligned rather than competitive partner on the MCO investment, since the debottlenecking directly improves the economics of Beach’s Cooper Basin acreage as well.

The broader Cooper Basin competitive landscape includes Strike Energy, Senex Energy, Cooper Energy, and a range of smaller explorers, none of whom operate at the scale or infrastructure depth of the Santos-Beach joint venture. The MCO project widens the operational advantage that Santos and Beach hold through their ownership of the Moomba Gas Plant and associated pipeline infrastructure. Third-party producers in the basin who rely on Santos infrastructure for gas processing and transport benefit indirectly from increased system capacity, but the primary economic upside flows to the joint venture operators.

Woodside Energy, Santos’ largest Australian peer, withdrew from merger discussions with Santos in 2025. The MCO investment is a clear signal from Santos management that the company is comfortable pursuing organic growth within its existing asset base rather than reorienting toward a transformative transaction. This is consistent with what Managing Director Kevin Gallagher described as disciplined growth around existing infrastructure.

What does the Scope 1 emissions reduction target mean for Santos in the context of its broader decarbonisation commitments in the Cooper Basin?

The MCO project is projected to reduce Santos’ Scope 1 emissions by approximately 40,000 tonnes of CO2 equivalent per year by eliminating gas-driven compression in favour of electric-driven equipment. For context, Santos’ Moomba Carbon Capture and Storage project, which commenced injection operations in late 2024, had stored close to 340,000 tonnes of CO2-equivalent by year-end 2024 and is now operating at nameplate injection rates. The combination of the CCS project and the MCO emissions reduction creates compounding Scope 1 improvement across the same operating area.

This matters for Santos’ institutional investor base, a significant portion of which applies ESG criteria to portfolio allocation decisions. A company that can demonstrate measurable Scope 1 reductions tied to operational infrastructure investments rather than offsets or paper targets is in a structurally stronger position relative to peers that rely exclusively on purchased abatement. The 40,000 tonnes per year target represents meaningful but not transformative progress against Santos’ total emissions profile, and the company has not disclosed how the MCO reduction integrates with its broader Scope 1 reduction trajectory.

How is Santos stock positioned heading into the MCO announcement, and does the market reaction align with the strategic significance of the decision?

Santos Limited shares closed at A$7.46 on March 6, 2026, reflecting a one-year gain of approximately 21.7 per cent and outperforming the S&P/ASX 200 benchmark over the same period. The 52-week range spans A$5.20 to A$8.06, placing the current price in the upper two-thirds of that range and comfortably above the 200-day moving average. The consensus analyst recommendation is Buy, with a 12-month price target of approximately A$7.96. Institutional sentiment has been constructive through early 2026, supported by Middle East conflict-driven oil price movement and Santos’ exposure to east coast Australian gas supply tightness.

The MCO announcement is capital-expenditure-positive in the near term, which may create modest pressure on free cash flow metrics during the three-year construction period. However, the fully budgeted nature of the spend and the prepayment financing structure from the South Australian government deal reduce the cash flow drag relative to an unhedged infrastructure commitment. The project’s IRR above 15 per cent with a path to 25 per cent on Central Fields full-field development should be viewed as value-accretive at the margin by analysts already carrying Buy ratings, but is unlikely to be a significant near-term share price catalyst given that the strategic logic of the Cooper Basin investment is already embedded in consensus models.

The more significant stock catalyst remains the closure of the gas supply agreement with the South Australian government by 30 June 2026. Confirmation of that agreement, including the prepayment structure, would de-risk the MCO project economics and provide contracted revenue visibility from 2030 to 2040 that the market does not currently have in its estimates.

Key takeaways: what does the Santos Moomba Central Optimisation decision mean for investors, the Cooper Basin, and east coast Australian gas markets?

• Santos has committed A$357 million net to a three-year infrastructure upgrade targeting more than A$600 million in lifetime capex and opex savings, with an IRR above 15 per cent at the project level and above 25 per cent on Central Fields full-field development.
• The Moomba Central Optimisation project is the enabling investment for Santos’ most productive remaining Cooper Basin reserve block, which holds more than half of the basin’s 2P reserves.
• Financing is partially structured around a prepayment from the South Australian government under a Key Term Sheet for 20 PJ per year of gas supply from 2030 to 2040. Conclusion of the full gas supply agreement by 30 June 2026 is the key near-term execution variable.
• The shift from seven gas-driven compressor stations to one electric-driven station reduces unit production cost by up to A$3 per barrel of oil equivalent and cuts Scope 1 emissions by approximately 40,000 tonnes of CO2 equivalent per year.
• Joint venture partner Beach Energy is aligned on the FID, having recently expanded its Cooper Basin exploration acreage and committed to a domestic gas supply growth strategy that benefits from improved basin infrastructure.
• Santos management has signalled continued commitment to organic growth around existing infrastructure, a clear strategic contrast to the failed Woodside merger discussions in 2025.
• At A$7.46 per share with a 52-week range of A$5.20 to A$8.06, STO trades comfortably above its 200-day moving average with consensus Buy ratings and a 12-month target near A$7.96.
• The MCO investment is not a near-term share price catalyst on its own, but confirmation of the gas supply agreement and prepayment structure by mid-2026 could be meaningful positive news for investors tracking project economics.
• East coast Australian gas buyers, particularly South Australian industrial customers, gain long-term supply security through the combination of the MCO capacity expansion and the Strategic Gas Reserve offtake agreement.
• Execution risk over the three-year construction period in a remote South Australian location, combined with historically weather-sensitive operations, is the primary variable that could shift actual returns away from modelled targets.