Classical fracture upscaling techniques are usually based on numerical or analytical solutions which can present some problems to capture the near-well flow behavior, leading to wrong well productivity index. In addition, grid cell size must be chosen carefully to maintain both connectivity and permeability tensor of fracture network in a reasonable simulation computational time. This paper proposes a near-well refinement in conjunction with a classic fracture upscaling technique in order to improve the accuracy of well productivity. The matrix porous media is respected to a microbial carbonate reservoir where discrete fractured network is composed by diffuse fracture pattern (small-scale fractures) and sub-seismic conductive fractures that strongly affect fluid flow. Fracture network density was defined using lithology as control driver. In this work, a dual-porosity system with a block cell size smaller than diffuse fractures was used as reference model (fine grid) for the upscaling method due to its quality to reproduce properly the connectivity between diffuse and sub-seismic fractures. The fracture upscaling method based on Oda′s solution (Oda, 1985) was applied to a coarser model defined by near-well refinements, which capture the fine grid fracture properties near-well. Homogeneous petrophysical matrix is applied in order to isolate the matrix heterogeneity effects. It was possible to adjust the main reservoir parameters (field average pressure, oil recovery factor and water cut) and advanced water front. The fine grid simulation time was drastically reduced using the proposed procedure.
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