Impact Potential of Hypersaline Brines Released into the Marine Environment as Part of Reservoir Pressure Management

This report describes an assessment of environmental impact potential arising from the possible disposal of hypersaline brines into the ocean as part of reservoir pressure management for Carbon Capture and Storage. We have used sophisticated high-resolution hydrodynamic models to assess a number of guided scenarios. Although the characteristics of some brines in their undiluted form would have a high environmental impact potential, we find that dispersion in a hydrodynamically active region like the North Sea acts to dilute disposed brine rapidly, such that the potential impact footprint (area exposed to environmentally damaging salinity or temperature) is small, generally measured in 10’s of meters depending on scenario and in-situ conditions. Contaminants within the released brines may have more impact potential, depending on concentration. We recommend consideration of brine release height to further limit impact potential.