Geomechanical Modeling and Monitoring of Fault Responses and the Potential for Earthquakes During Underground CO2 Injection

The importance of geomechanical processes and modeling associated with large-scale CO2 injection operations can hardly be overemphasized. In particular, recent concerns about the potential for injection-induced fault reactivation and earthquakes are key technical issues that need to be addressed. Under these circumstances, coupled fluid flow and geomechanical modeling is an important tool in site specific risk analysis and for designing injection operations in terms of sustainable injection rates. It appears that future commercial scale CO2 storage operations may cause considerable pore pressure perturbation over distances of tens of km. In this context, recent model simulations of injection-induced fault reactivation and potential earthquake magnitudes will be presented. These model simulations show what it takes to create a magnitude 3 or 4 earthquake that would not result in any significant surface damage, but would certainly raise concerns in the local community and could also affect the containment of the stored CO2. Observations from ongoing CO2 storage projects will also be discussed, in particular the In Salah project, with regard to injection induced fault responses and seismicity.