Abstract: In the past two decades, various reservoir upscaling theories and methods have been proposed for reservoir characterization and reservoir simulation. They are classified into five categories such as power-law average method, renormalization technique, pressure-solver method, vector method and pseudo-function technique. The common problem of conventional reservoir upscaling methods tends to smear out the spatially continuous permeability extremum strips like shale intercalation and fracture. However, the simulation and the practice for heterogeneous reservoirs have shown that oil recovery, especially breakthrough recovery mainly depends on the spatial connectivity of the extreme permeability values. This paper discusses how to deal with the permeability extrimum strips in the upscaling process and how to make an upscaling for natural fractured reservoir and carbonate reservoir, which are the remained major challenging problems in this area.

Key words: model, reservoir simulation, grid, upscaling