ABSTRACT

Identifying basin areas that are prospective for the geological storage of carbon dioxide (GSC) is essential to support Australia’s transition to a net-zero emissions energy future. Geoscience Australia has developed a play-based common risk segment (CRS) mapping approach to evaluate GSC prospectivity based on four geological risk elements: (1) injectivity, (2) storage effectiveness, (3) containment and (4) structural complexity. Various geological criteria are used to evaluate these risk elements using post-drill data/analysis, gross depositional environment (GDE) maps, rock property maps, and depth structure and isochore maps. Rock property maps form an essential component in defining the CRSs for GSC prospectivity maps. This paper provides a case study from Geoscience Australia’s assessment of the GSC potential for the western Eromanga Basin (WEB). Rock property maps are constructed in the Petrel Software Platform (©SLB). Inputs for these models include a 3D structural model incorporating 14 play intervals, GDE maps and sub-surface rock properties derived from petrophysical analyses of wireline log data (such as volume of clay/shale, total and effective porosity, Timur-Coates permeability and apparent water salinity). Key outputs from the geological model include permeability thickness (used to assess injectivity), effective porosity (used together with depth structure maps to assess storage effectiveness), and net seal thickness (used to assess containment). Results from the CRS mapping show the WEB has potential to support industrialscale (>1 mtpa) GSC projects using migration assisted storage in structurally simple areas where there is favourable stacking of effective reservoirs overlain by impermeable seals.