Experiments and numerical simulations of fluid flow in a cross layered reservoir model

This paper reports on studies of two-dimensional local saturation development in a cross layered reservoir model. Numerical simulations and experimental studies have been performed on a heterogeneous reservoir model consisting of three blocks of porous material with capillary and permeability contrasts connected at a dip angle of 45°. The physical reservoir model measured 22 cm × 5 cm × 5 cm and was composed of blocks of Vosges sandstone alternating with Aerolith-10, an artificial sintered porous medium with high porosity and permeability. The physical properties, porosities, permeabilities, capillary pressures, and end-point saturations of the blocks composing the heterogeneous medium were measured independently on isolated samples. A series of oilfloods and waterfloods were performed, and dynamic two-dimensional saturation fields were measured by gamma-ray attenuation. After drainage, during a no-flow state at low water saturation, we observed a redistribution of fluids near the boundaries of permeability contrasts due to capillary pressure differences between the blocks. The two-dimensional saturation fields recorded during the low-rate waterfloods showed a different behavior in different layers due to the contrasts of permeability and capillary pressure. Recovery efficiency by waterflooding isolated samples does not necessarily predict local recovery in composite models. Good reproducibility was obtained by performing different experiments with the same boundary conditions and petrophysical properties. Two-dimensional numerical simulations performed with the full-field commercial simulator ECLIPSE confirmed the observed experimental behavior. However, the simulated recovery from each block did not match the experimental results. We concluded that two-dimensional local saturation information in larger scale three dimensional reservoir models significantly improves the interpretation of the recovery mechanisms in heterogeneous porous media.