Abstract. Geologic carbon storage, as well as other geo-energy applications, such as geothermal energy, seasonal natural gas storage and subsurface energy storage, imply fluid injection/extraction that causes changes in the effective stress field and induces (micro)seismicity. If felt, seismicity has a negative effect on public perception and may jeopardize wellbore stability and damage infrastructure. Thus, induced earthquakes should be minimized to successfully deploy geo-energies. However, the processes that trigger induced seismicity are not fully understood, which translates into a limited forecast ability of current predictive models. We aim at understanding the triggering mechanisms of induced seismicity and to develop methodologies to minimize its occurrence through dimensional and numerical analysis. We find that the properties of the injected fluid, e.g., water or CO2, have a significant effect on pressure buildup evolution and thus, on fracture/fault stability. In addition to pressure changes, the injected fluid usually reaches the injection formation at a lower temperature than that of the rock, inducing rock contraction, thermal stress reduction and stress redistribution around the cooled region. If low-permeable faults cross the injection formation, local stress changes are induced around them which may reduce their stability and eventually cause fault reactivation. To minimize the risk of inducing felt seismicity, we have developed characterization techniques to reduce the uncertainty on rock properties and subsurface heterogeneity both for the screening of injection sites and for the operation of projects. Overall, we contend that felt induced seismicity can be minimized provided that a proper site characterization, monitoring and pressure management are performed.
Recommended Practices for Managing Induced Seismicity Risk Associated with Geologic Carbon Storage
