CO2BLOCKSEISM, a tool for screening CO2 storage resources constrained by the risk of induced seismicity

Energy systems models analyzed by the UN Intergovernmental Panel on Climate Change (IPCC) suggest that geologic carbon storage (GCS) at annual rates of several gigatonnes may be required to effectively mitigate the climate change crisis. Deployment of GCS at such large scales needs to address uncertainties about the availability and use of subsurface resources. A major concern is the growing risk of induced seismicity with the scale of implementation as wastewater disposal at comparable rates led to a surge in seismic activity in the central and eastern US in the 2010s. We develop an open-source tool, named CO2BLOCKSEISM, for screening subsurface storage resources constrained by the risk of induced seismicity. It relies ‎on (1) analytical solutions of the pressure response of saline aquifers to multi-site CO₂ injection at time-varying rates and (2) ‎Monte Carlo simulations for ‎estimating slip probability on mapped faults under inherent ‎uncertainties of the geomechanical parameters. Employing simplified physics models in this tool enables the evaluation of storage ‎resources at regional scales under different scenarios of site number and distance between them. We demonstrate the application of the tool to estimating storage resources in the Utsira Formation in the Norwegian North Sea. We find that nearly 12.5 Gt CO₂ can be safely stored in this ‎region over 50 years of continuous injection. The estimated storage capacity, although large, is much smaller than estimates of around 18 Gts subject to the caprock fracturing limit. We conclude that the use of induced seismicity as the leading physical constraint allows for more reliable estimates of the potential rates of GCS scale-up at regional and global scales.