as related to the DOE and CSLF methods, is the total pore space of the assessed area that can be accessed by injected CO2.
This is obviously an overestimation since it would be technically impossible to access all the pore space in the reservoir.
The two methods only differ at this point by the inclusion of irreducible water saturation.
The CSLF method states that the theoretical storage resource is the pore space minus the irreducible water saturation.