In most cases, the saline formations have a large extent and for all practical purposes are open or “infinite acting” systems. However, in some cases, the saline formations are compartmentalized by lateral flow boundaries such as low- permeability zones created by changes in pore structure or sealing faults. In these cases, the saline formation would act in a closed or semiclosed manner, as suggested by Zhou and others (2008). One of the first issues to address is what type of boundary conditions exist in the assessment area. This will have a large impact on the injection strategy and dictate what type of resource/capacity estimation technique will be utilized. For the purposes of this work, two scenarios have been considered: 1) a closed system with compartmentalized units in a formation that does not allow any movement of formation fluids out of the assessment area and 2) an open system, where the injection takes place in a large regional system in which formation brine is able to migrate away from the injection point in an infinite acting way, with no formation pressure buildup due to compartmentalization (Zhou and others, 2008) (Figure 3). It is worth noting that semiclosed systems do exist, the characteristics of which may have significant consequences to CO2 storage security. However, because of the complex nature of these systems, they have not been included in the development of the storage coefficients described in this report.