For this month’s Office Hours, we had a presentation from ResFrac Senior Reservoir and Completions Engineer, Ankush Singh, on modeling CO2 injection and long-term storage using ResFrac. The true injection capacity of a CO 2 storage site should be calculated in terms of how much fluid can be injected economically, while minimizing the risks such as caprock failure and induced seismicity. We will discuss some of the fully coupled 3DResFrac simulations we performed to better understand the changes in the subsurface resulting from CO2 injection. The simulations demonstrate the importance of utilizing a fully integrated 3D hydraulic fracture, geomechanics and compositional fluid flow simulator to understand the subsurface risks and optimize CO 2 injection.