Pre-screening of induced seismicity risks for CO2 injection at Trüllikon, Switzerland

• Published in: International journal of greenhouse gas control Vol. 138; p. 104239
• Main Authors: Schultz, Ryan, Rinaldi, Antonio Pio, Roth, Philippe, Madritsch, Herfried, Gunatilake, Thanushika, Wiemer, Stefan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2024
• Subjects: Bowties; Carbon capture & storage; Fault slip potential; Geomechanics; Induced seismicity; Pre-screening; Red-light; Risk; Traffic light protocol; Induced seismicity; Carbon capture & storage; Geomechanics; Traffic light protocol; Red-light; Bowties; Risk; Pre-screening; Fault slip potential
• ISSN: 1750-5836
• DOI: 10.1016/j.ijggc.2024.104239

•We perform a pre-screening analysis for the risks of induced seismicity due to a prospective carbon inection operation near Trüllikon, Switzerland.•We follow the concept of a bowtie for risk management, where barriers to prevent threats to the risk are appraised alongside mitigation measures to reduce the severity/likelihood of consequences.•Barriers to threats are appraised through fault slip potential analysis and modelling of expected pore pressure increases due to CO2 injection.•Mitigation measures are considered though the design of a risk-based traffic light protocol.•We then discuss how these risk management results would translate into monitoring performance targets. Successful carbon injection operations depend critically on the management of risks, like induced seismicity. Here, we consider the bowtie risk management framework to organize pre-screening efforts around a prospective CO2 injection operation near Trüllikon, Switzerland. First, potential barriers/threats are appraised via a literature review of the regional seismotectonics, hydrogeology, and nearby induced seismicity cases – which suggests a natural propensity for earthquakes because of the proximity to the Neuhausen Fault and a lack of effective underlying hydrogeological barriers. Next, we engineer barriers to fault reactivation by quantifying the fault slip potential. The closest (∼700 m) and most susceptible (∼3.0 km) portions of the Neuhausen Fault would require ∼1.7 MPa and ∼0.47 MPa for reactivation, respectively. The most susceptible (unknown) faults are normal slip (168° strike) that require ∼0.23 MPa for reactivation. Injection simulations indicate pressure changes on Neuhausen Fault segments of 0.01–0.05 MPa – values that are 1–2 orders-of-magnitude smaller than those needed for fault reactivation. These engineered barriers limit the potential for fault reactivation. However, if these barriers prove totally ineffective, we have also designed a traffic light protocol as a reactive mitigation measure. Forecast estimates of nuisance, damage, and fatalities are used to infer the last-possible stopping-point based on a comparison with operation-ending risks encountered at Basel and St. Gallen. This indicates a red- and yellow-lights of MW ∼2.0 and MW ∼0.0, respectively. We synthesize these disparate pre-screening analyses to recommend performance targets for real-time seismic monitoring. Future CO2 operations will likely find our approach helpful for designing effective risk management.