Central Australia’s Cooper-Eromanga Basins have strong potential to become a world-class hub for geological carbon storage. However, deep reservoir sequences with high stresses and pore pressures create major uncertainties for fault stability during carbon dioxide (CO2) injection. Understanding these geomechanical complexities is critical to de-risking carbon capture and storage (CCS) projects, as unfavourable stress conditions may compromise caprock integrity, trigger-induced seismicity and ultimately lead to CO2 leakage. This study compiles an extensive set of in-situ stress data and integrates it with existing large-scale geomechanical-numerical models to evaluate the basin-scale stress state. The updated stress map for the Cooper-Eromanga Basins shows a dominant east–west orientation of the maximum horizontal stress but with local re-orientations of up to 35° near faults and lithological contrasts. Vertical stress gradients range from 15.5 to 23.8 MPa/km, while minimum and maximum horizontal stress gradients vary between 12.4 to 27.2 MPa/km and 21.9 to 50 MPa/km, respectively. 1D Mechanical Earth Models highlight the influence of lithological contrasts on stress magnitudes, while 3D geomechanical models reveal significant vertical and lateral variations in stress regimes. Basin-scale results suggest a dominant strike-slip stress regime, with significant variations towards normal faulting at different depth intervals mainly related to lithology changes, and variable differential stresses. This study highlights the need for predictive 3D stress modelling as a critical tool to improve understanding of geomechanical risks and to ensure the safe deployment of CCS in this region.
Tavoosiiraj et al. (Wed,) studied this question.