Reservoir engineers are often faced with heterogeneous core material, for which conventional methods of estimating relative permeability are susceptible to error and may lead to incorrect conclusions regarding displacement efficiency, wettability and reservoir performance. This paper focuses on new techniques for judging the validity of relative permeability data obtained on heterogeneous cores.
Numerical simulation is used to quantitatively analyse the impact of typical heterogeneities. For unsteady-state tests analysed by conventional methods, it is shown that typical heterogeneities influence relative permeability in a systematic way, and that parts of the measured curves still may provide valid data. The error introduced by heterogeneities is quantified and correlated with the Dykstra Parson coefficient. Further, it is shown that the steady-state technique is more robust than the unsteady-state measurements in case of stratified material.