ABSTRACT

The western Eromanga Basin comprises a series of deep saline aquifers, covering more than 1,000,000 km² of central Australia. The basin was evaluated as a potential CO₂ sequestration target by Geoscience Australia as part of the Australian Future Energy Resources Project, supported by the Australian Government. RISC Advisory has provided Geoscience Australia with subsurface technical expertise to assist in quantifying the potential estimated ultimate storage volume range under the Society of Petroleum Engineers Storage Reservoir Management System framework. Given the vast area of investigation and relatively sparse geological information available, several industry standard subsurface engineering techniques were adapted by RISC to suit the specific needs of this project. These techniques included permeability upscaling to estimate aerial and vertical storage efficiency, estimation of CO₂ fluid properties at reservoir temperature and pressure, and project development parameters such as well count, well injection rates, reservoir pressure with increasing storage volume and water offtake rates under different aquifer constraint scenarios. Low, best and high estimated storage volumes were generated using probabilistic uncertainty in both the basin-scale geological model and engineering workflows to give a range of CO₂ storage volumes. This work describes the technical basis for the theoretical CO₂ storage volume assessment of the western Eromanga Basin, and project development parameters for a typical 50 Mt storage project.