A criterion for ordering individuals in a composite core

We present a theoretical study of how the properties of the individual cores in a composite core influence the measured relative permeabilities of a waterflood. The assumptions are that relative permeabilities and porosities are equal for all individuals in the composite core, and also that the individual capillary pressures are scaled by a Leverett-J relationship. Realistic data from a North Sea sandstone reservoir are used to select all core and fluid properties. Based on the results of this study, we propose a new criterion for how to order the individuals in a composite core. The best ordering is after decreasing permeability along the flow direction, i.e., such that the core with the lowest permeability is placed at the outlet. This ordering will produce a residual oil saturation closest to the true one. Our new criterion is in conflict with what we believe is common practice, as well as with the Huppler criterion [Huppler, J.D., 1969. Waterflood relative permeabilities in composite cores. JPT, 539-540.].