Integrated approach to CO2 storage assessment in the offshore South Perth Basin, Australia

Brief description

As part of the Australian Government National CO2 Infrastructure Plan (NCIP), Geoscience Australia is undertaking CO2 storage assessment of the Vlaming Sub-basin located offshore Western Australia in the southern Perth Basin. The Vlaming Sub-basin is a Mesozoic depocentre containing up to 14 km of sediments. Close proximity of the basin to industrial polluters in the Perth area dictates the need to find CO2 storage solutions in this basin. The main reservoir unit identified as suitable for storage of CO2 is the Early Cretaceous Gage Sandstone deposited in paleo-topographic lows of the Valanginian breakup unconformity. The reservoir unit is laterally extensive (over 1,500 km2) and over most of the area reasonably thick (100 - 300 m). It lies at depths between 1400 and 2000 m below the seafloor, which is suitable for injection of the supercritical CO2 and makes it an attractive target for the long-term storage. The reservoir unit is overlain by a thick deltaic to shallow marine succession of the South Perth Shale, which represents a regional seal in the area. Carbon Storage taskforce estimated that up 1 GT of CO2 can be stored in the Gage Sandstone. The first assessment of the Vlaming Sub-basin undertaken by CO2CRC focused on evaluation of the reservoir unit and overall storage capacity. The current study is based on interpretation and integration of the seismic, well and marine datasets, both existing and acquired since the previous assessment. It includes detailed analysis of reservoir and seal properties and a comprehensive evaluation of the seal integrity risks to allow a more accurate and realistic modeling for CO2 storage.

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Statement: designed in-house at Geoscience Australia