Comparison of Single Porosity and Dual Permeability Systems Applied to Naturally Fractured Carbonate Reservoirs

Abstract

The fine-grid single porosity system is commonly used as reference in upscaling matches. The fine-grid approach induces that all important flow process relative to small scale heterogeneities are not neglected. In naturally fractured carbonate reservoirs, the matrix-fracture interaction at small and large scale fractures can be an issue using a single porosity system without applying a pseudo-function, even under a fine-grid model. Using a fine-grid dual permeability system as reference, given is flexibility to take into account matrix-fracture interaction in two systems, we match the reservoir behavior (field average and well pressure, oil recovery factor, water cut, injected water front) applying a pseudo-relative permeability curve to a fine-grid single porosity system with equal petrophysical values. The methodology was applied in mini-models in order to make possible the flow simulation of a fine grid dual permeability system, given the higher simulation computational time in these formulations comparing to single porosity systems. Given the fact that dual porosity or dual permeability systems are normally applied at simulation scale, this work also gives a great understanding of the sensitivity in approach a dual permeability system, given the both small and large heterogeneities present in a fine-grid model.