Session 20. Oral Presentation for: Modelling the impacts of multiple large-scale CO2 storage projects within one region: lessons for operations and regulation

Presented on 20 May 2026: Session 20 Australia’s offshore carbon capture and storage regulations are largely site-centric and framed around the CO2 plume footprint. While proponents must demonstrate safe pressure limits to assure containment, far-field pressure effects resulting from multiple simultaneous CO2 storage operations could impact storage capacity, injectivity, plume migration pathways, hydrocarbon accumulations, monitoring strategies and regulatory considerations. To quantify these regional effects, we completed an integrated, multiple injection site assessment of the K20 sequence in the Barrow–Dampier sub-basin. Five storage projects were located within the model domain, each supported by six wells injecting 1 MtCO2/year/well for 30 years. Boundary conditions ranged from closed to finite-aquifer support (Carter–Tracy r-ratios 1.5–10) and simulations examined isolated, simultaneous and staggered start-ups, and scenarios with/without a nearby gas field. Under closed boundary conditions, 514 MtCO2 was stored over 30 years, versus ~924 Mt if sites were assessed in isolation (~185 Mt/site), indicating that single-site assessment can overestimate dynamic capacity. With finite external aquifer support, CO2 storage totals increased to 591 Mt (r = 1.5), 861 Mt (r = 3) and ~924 Mt (r ≥ 5); for r ≥ 5, design rates were sustained, and per-site storage converged to ~185 Mt. Plume monitoring footprints were sensitive to boundary conditions and were consistently smaller under multi-site than isolated modelling. Project sequencing mattered where aquifer support was limited (early-mover advantage), and coexistence with hydrocarbons showed mixed effects: storage capacity gains, but residual hydrocarbon trapping. These results underscore the importance of integrated regional modelling to yield realistic capacity/injectivity estimates, defensible monitoring footprints and reduced-risk coexistence with petroleum operations. To access the Oral Presentation click ‘Supplementary data’ below. To read the full paper click here