| A typical geo-cellular model contains millions of grid blocks and needs to be up-scaled before the model can be used as an input for flow simulation. Available techniques for upgridding vary from simple methods such as proportional fractioning to more complicated methods such as maintaining heterogeneities through variance calculations. All of these methods are independent of the flow process for which simulation is going to be used, and are independent of well configuration. A new upgridding method is proposed which preserves the pressure profile at the upscaled level.;It is well established that the more complex the flow process, the more the detailed level of heterogeneity needed in the simulation model. In general, ideal upscaling is the process which preserves the "pressure profile" from the fine scale model under the applicable flow process. In our method, geological models are upgridded using simple flow equations in porous media.;The new method is currently developed for single phase flow; however, the new method is tested for both single phase and two phase flows for 2D and 3D cases. The methodology fundamentally differs from the other methods which also try to preserve heterogeneities. In those methods, grid blocks are combined which have similar velocities (or other properties) by assuming constant pressure drop across the blocks. Instead, this new method combines the grid blocks which have similar pressure profiles. The procedure is analytical and, hence, very efficient, but it preserves the pressure profile in the reservoir. The grid blocks (or layers) are combined in a way that minimizes the difference between fine scale and coarse scale pressure profiles. In essence, for single phase flow the new method combines the layers that have similar average pressure profiles and, for two phase flow, it combines layers that have closer breakthrough times or in other words, layers which have closer time of flights.;In addition, two new criteria are provided, Design Factor (DF) and Error Per Layer (EPL) that allow us to choose the optimum number of the layers more accurately so that the critical level of heterogeneity is preserved. These criteria provide insight into the overall level of heterogeneity in the reservoir as well as the effectiveness of the layering design.;In real field applications, comparison of the results of the new method with proportional layering and a variability based method is provided to show that, for the same number of layers, the proposed method better captures the dynamic results of the fine scale model. The new method shows that the layer merging not only depends on the variation in the permeability between the grid blocks, but also on the relative magnitudes of the permeability values. |
