Gorgon Carbon Capture and Storage – Insights and Lessons Learned

Robert Root (Chevron Australia) will provide an overview of Gorgon CCS including performance to date, system optimization, and key lessons for other CCS projects. The Gorgon Liquified Natural Gas (LNG) plant is supplied by gas from two foundation fields: Jansz which has low reservoir CO2, and Gorgon which is relatively high in reservoir CO2 (~14%). The design of Gorgon Project included systems to extract CO₂ from the reservoir gas stream feeding the LNG plant and inject it into the Dupuy Formation below Barrow Island (BWI) for permanent storage. Since 2019 CO₂ has been injected into the Dupuy at globally significant rates with over 10 million tonnes injected, however the system has been limited by the capacity to manage reservoir pressure through producing water from the Dupuy Formation and injection into the overlying Barrow Group. Activities are currently underway to increase pressure management capacity including side-tracking and re-completing existing wells, drilling additional wells, and installation of surface filtration facilities.

CO₂mpartmentalising Climate Change: Perth Basin’s Role

Julia Cass (DEMIRS) will discuss reservoir quality controls in the Perth Basin that have been evaluated to rank carbon storage targets for a CO₂ Storage Atlas being prepared by the Geological Survey of Western Australia. The key attributes for the most prospective targets include thick intervals with high net-to-gross passing cut-off criteria of shale volume below 30% and porosity greater than 10% at depths suitable for supercritical CO₂ storage. Reservoir heterogeneity is preferred as it permits greater lateral plume migration by enhancing residual gas trapping thereby boosting storage efficiency. These attributes alongside seal effectiveness determine the most suitable storage intervals.

The Cattamarra Coal Measures emerged as the highest-ranked storage interval of the evaluated targets. It is characterised by thick, high net-to-gross sections with coarse-grained channel sands providing excellent injection potential. Burial and temperature control diagenesis which naturally degrades porosity and permeability with depth ultimately defining the lower limit of intervals prospective for storage. A combination of temperature modelling, petrophysical analysis and depth mapping has been utilized to delineate the Cattamarra Coal Measures reservoir target and assess the overlying regional seal of the Cadda Formation.

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