Triggering Mechanisms and Mitigation Strategies of CO2 Injection-Induced Seismicity in the Canada Weyburn Field

Abstract Induced seismicity poses a key technical and regulatory challenge for the long-term deployment of carbon captureand storage (CCS) projects. This study investigates the geomechanical response of the Weyburn reservoir to sustained CO2 injection using a fully coupled thermal-hydrological-geomechanical-chemical (THMC) simulation framework implemented in CMG-GEM. A 3D geological model was constructed based on integrated core analysis, wireline logs, and seismic interpretation to account for structural heterogeneity and fault networks. The simulation results indicate that pore pressure buildup is the primary driver of fault instability, especially in proximity to critically stressed faults. Although thermal contraction and mineral dissolution contribute to changes in stress and stiffness, their effects remain secondary under typical injection scenarios. Field-recorded microseismic events from 2003 to 2010 align spatially with modeled zones of elevated pore pressure, particularly along a northeast-trending fault system. These findings underscore the importance of incorporating fault geometry and in-situ stress conditions into storage site evaluation and operational planning. The work establishes a reliable modeling approach to support seismic risk management in geological CO2 storage projects and informs the design of safe injection strategies.