The DOE method assumes that all seven terms used to calculate the storage coefficient can be rolled into a single term that can be applied to the entire pore volume of a given formation to come up with an effective storage resource.
This assumes that CO2 injection wells can be placed regularly throughout the formation to maximize storage and that the saline formation is an open system.
The CSLF method can also be applied to an open system by applying a storage coefficient using a series of variables similar to the ones used in the DOE method.