SpecialReport: CCS Feasibility Studies falls between 18 and 30 GT today. This capacity will continue to grow with ongoing production. Potential Concerns CO2 injectivity and reservoir integrity are highly dependent on the geomechanical behavior of the stimulated fracture network under high-pressure injections and the interaction of this network with undiscovered geologic faults. Long-term injection into an unconventional reservoir may extend the initial hydraulic fracture network by changing poroelastic stresses, which may vary substantially from the initial state because of slowly pressurized rock volumes or nearby fracturing or production activities. Such changes can occur even if the well's operator keeps injection pressures below the fracture gradient. Generally, a CO2 storage interval within an unconventional reservoir is adjacent to overlying or underlying intervals subject to hydrocarbon production or saltwater disposal. In these cases, evaluating the geomechanical effects of CO2 injection into a specific interval cannot be done by modeling that specific interval alone but rather requires a poroelastic model that spans several overlying or underlying layers. This is largely because of the extension of pore pressure diffusion through a conductive fault or far-field poroelastic stress disturbance during long-term injection or production. Also, an unconventional reservoir's ability to hold pressurized CO2 in the long term may be compromised by a caprock fault breach resulting from reactivation of this fault. These problems can be addressed rigorously using a fully coupled poroelastic model that solves for pore fluid flow, fracture fluid flow and stress analysis and outputs a propagated fracture network or fault reactivation criterion. For instance, porelastic models have been developed in the commercial software program Abaqus and applied extensively to simulate hydraulic-fracture propagation; interpret microseismic surveys of hydraulic fracturing; analyze saltwater-disposal fault reactivation in cases with concurrent disposal and production in stacked reservoirs; and simulate hydraulic fracture reopening. Past geomechanical studies on fault reactivation confirm that the modeling domain must extend beyond the storage interval. The workflow and principles in these studies can be readily applied to CO2 storage projects. A commonly adopted fault reactivation criterion is the Coulomb Failure Stress (CFS), which involves shear stress,