Moomba CCS: a subsurface lookback at the first year of injection performance of Australia’s first large-scale onshore carbon capture and storage project

Santos made the first significant gas discovery in the Cooper Basin at the Gidgealpa Field in 1963. More than 60 years later, Santos is again leading the way in the Cooper Basin with successful start-up of the Moomba Carbon Capture and Storage (CCS) project in October 2024 which has the capacity to permanently store up to 1.7 million tonnes of CO2 equivalent. This paper reviews the first year of project performance from a subsurface perspective as CO2 is injected into the depleted Toolachee reservoirs of the Strzelecki–Marabooka fields via five injector wells. The paper discusses the data gathered through the ongoing monitoring and verification activity demonstrating the safe storage of CO2 within the complex. This includes injection telemetry, pressure monitoring through the storage complex and insights from the passive seismic monitoring array. As the first large-scale onshore CCS project in Australia, this project will yield subsurface insights which can help to inform other CCS projects onshore Australia and provide a benchmark of effective, fit for purpose monitoring and verification activities.