In order to model a WAG process in a North Sea oil field integrated pore-to-field scale multiphase upscaling was performed[1]. The upscaling procedure included two steps. A pore-to-core upscaling step was based on pore network modeling. It resulted in relative permeabilities and capillary pressure functions, which represent the Darcy-scale properties of rock types. The saturation functions were utilized in the next upscaling step.

In this paper we describe the second upscaling step, from centimeters to meters scale, which was performed to derive multi-phase flow functions for the field-scale simulation. This step takes into account heterogeneity of the facies as well as gravity effects, and is based on steady-state upscaling technique. The upscaled flow functions resulting from the second step depend both on the flow direction and on the flow rate (or pressure gradient). The rate sensitivity of the upscaled functions is different for the two directions, horizontal and vertical. The upscaled flow functions in the horizontal direction are rate insensitive, while the vertical flow functions appear to be quite sensitive to the vertical rate.

Derivation, analysis and validation of the upscaled flow functions are described. The latter is done by comparison of the fine grid simulation and homogenized coarse grid simulation in 2D, vertical crossection, and also by comparison of the predicted oil production with field observations.

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