Geological storage of CO_2 is one practical method for reducing large volumes of greenhouse gas emissions. In Australia, research into this methodology is being conducted by the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), continuing on from the GEODISC Program. Results from the geological modelling of three deep saline formations as potential storage sites and the comprehensive workflow undertaken to achieve this are presented in this paper. The site-specific research focussed on three main aspects: injectivity, containment and capacity. Injectivity is a function of the reservoir's quality, geometry and connectivity. The development of a sequence stratigraphic framework and sedimentary depositional model for the potential sites provided information about the reservoir distribution and the likely lateral and vertical continuity. Containment issues include the distribution and continuity of the seal, the seal capacity (maximum CO_2 column height retention), potential migration pathways (structural trends and formation water flow direction and rate) and the integrity of the reservoir and seal (fault/fracture stability and maximum sustainable pore fluid pressures). Based on the geological assessment of reservoir continuity and structural trends, stratigraphic and structural traps were identified, and the most suitable locations for injection recommended. Storage capacity was assessed via cellular 3D geological models, built from the sequence stratigraphic framework and populated stochastically with reservoir properties. Due to the nature of geological variation, each potential storage site needs to be assessed individually; however, a similar workflow can be applied to all site evaluations. The geological complexity of any potential CO_2 storage site is best addressed by a multidisciplinary research effort, which can provide an integrated and comprehensive site evaluation for geological storage of CO_2.
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