Carbon dioxide plume prediction for site assessment and fault leakage risk in a seismically active region (Taranaki Basin, New Zealand)

This study investigates the potential for CO 2 storage in the depleted Maui-A gas field offshore New Zealand, focusing on CO 2 migration, storage capacity, and the risks of leakage related to reservoir faults and seismicity. We simulate multi-well CO 2 injection scenarios at a total rate of 3 Mt/year for 80 years, amounting to 240 Mt of CO 2 injected. Our study highlights the importance of considering heterogeneity related to the sedimentary architecture of the reservoir, which can significantly influence the lateral migration of CO 2 . The evolution of the CO 2 plume is also analyzed with respect to the presence of faults. Faults intersecting the reservoir pose a potential pathway for CO 2 leakage. Fault stress data suggest that these faults may be near critically stressed and therefore prone to release fluids or being reactivated during an earthquake along nearby larger faults. The analysis of reflection seismic data reveals gas-related anomalies along faults, suggesting that the faults have leaked previously. Such leakage was reproduced in our model. Although no significant CO 2 leakage was predicted under typical conditions, fault-related leakage could thus occur if these faults experience increased fluid pressure or seismic events. Future work should focus on detailed well-specific modeling, fault behavior analysis, and enhanced monitoring techniques to assess leakage risks, refine injection strategies, and ensure the long-term integrity of CO 2 storage in the Maui-A field. This research provides valuable insights into the complexities of CO 2 storage and its associated risks in seismically active regions. • CO 2 injection at Maui-A field modelled at 3 Mt/year for 80 years. • Reservoir heterogeneity significantly affects CO 2 plume migration. • Reflection seismic data suggest gas-related anomalies along reservoir faults. • Seismically induced pressure changes may lead to fault leakage