The prediction of impact and anomaly criteria for leakage detection from offshore carbon storage sites through a comprehensive coupled network of hydrodynamic and biogeochemical models

This investigation describes prediction of environmental impacts arising from potential seepage or leakage from under seabed carbon storage sites through a complex multi-phase, multi-scale modelling system in coastal waters. Monitoring is required for assurance, detection and mitigation. However, it is crucial to develop simulation models that can replicate observed behaviours and can be extrapolated to many different scenarios. It is shown that a coupled modelling system based on laboratory scale and in-situ experiments, along with knowledge of natural variability, can be used to quantify impact potential and derive highly sensitive indicators of anomalies which might arise from leakage in order to facilitate detection and assurance. The local effects are shown to be affected greatly by the water currents; with momentary spikes in pCO₂ and pH caused by tidal oscillation. Model outcomes feed into further studies allowing the development of systems to optimize detection criteria and monitoring strategies, providing effective methodologies for quantification of CO₂ fluxes across the seabed and dispersion in the water column, informing the temporal and spatial scales required for effective chemical monitoring.