UPSCALING METHOD OF RELATIVE PERMEABILITY FROM PLUG CORE TO WHOLE CORE

This paper presents the results of the interpretation of several unsteady-state coreflood experiments and discusses a method to estimate the relative permeability of the whole core using the data of the smaller scale cores and their characteristics. A water displacement test was conducted on a heterogeneous carbonate whole core (target core), then a series of the same test followed on the several plug cores that were extracted from the target core. Each test on the plug cores was interpreted by 3D coreflood simulation model that was constructed based on the detailed core characterization data. A newly developed simulation matching program called GEMAP * (1) that adopted genetic algorithm was employed to derive a set of normalized kro/krw and Pc curves representing each pore-type as grid data. The relative permeability curves of the plug cores were computed by the two-phase upscaling in-house program called CAVLUP * (2) that was initially developed for reservoir-scale upscaling problem. Both capillary-limit and viscous-limit upscaled kro/krw curves were computed by the program. The kro/krw curves were also determined by different method i.e. steady-state coreflood simulation and compared with the upscaled curves. The result showed that the capillary-limit upscaling method could reasonably reproduce the kro/krw curve generated by steadystate coreflood simulation of the same displacement velocity to that of the actual experiment. Based on the statistical data of porosity, permeability and pore-type, 3D stochastic models were constructed for the target core. A total of 100 kro/krw curves were computed using CAVLUP. On the other hand, 3D deterministic model was constructed to re-optimize the kro/krw and Pc curves of each pore-type and compute kro/krw curve by simulation matching. The result showed that the average upscaled curve of the stochastic models was close to that of the optimized model. It was concluded that the kro/krw curve of the target core could be reasonably estimated from plug-core-scale data by the same upscaling method as applied to reservoir scale problem.