A simplified physics model for estimating subsurface CO2 storage resources constrained by fault slip potential

This is the authors' abstract. We don't add key points for this paper.

Carbon Capture and Storage (CCS) at rates of several gigatonnes (Gt) per year may be needed to mitigate climate change. However, one major uncertainty is that the risk of injection-induced earthquakes may grow with this scale of deployment. In this work, we develop a tool, named CO2BLOCKSEISM, which uses simplified physics models to screen subsurface storage resources constrained by fault slip potential at regional scales. The tool relies on (1) analytical solutions for the pressure response of saline aquifers to multi-site CO 2 injection at time-varying rates and (2) a Monte Carlo-type probabilistic model for evaluating the fault slip probability incorporating uncertainties in geomechanical variables at the basin scale. Integration of the two modules yields the temporal evolution of slip probability for mapped faults. We validate the approach against seismic activity in Oklahoma caused by basin-wide, low-pressure subsurface wastewater disposal at equivalent rates to large-scale CCS. We show that CO2BLOCKSEISM can capture key features of induced seismicity in this region. We apply the methodology to the southern Utsira Formation, Norway. We find that approximately 12.5 Gt of CO 2 can be stored in this region over 50 years of continuous injection while maintaining the stability of major faults that could otherwise induce felt earthquakes. The use of fault-slip potential as a limiting condition may enable more restrictive and realistic estimates of the potential for rates of scale-up of CO 2 storage regionally and globally.