Experimental Mechanics of Fractured Porous Rocks

An experimental coreflooding test was planned to determine residual oil saturation in a double porosity rock (vuggy-fracture network, and matrix). Oil-water contact advance, produced by reservoir production, was scaled by dimensional analysis and experimentally performed in the laboratory, in order to calculate residual oil saturation in the region invaded by water in a giant naturally fractured reservoir in the Gulf of Mexico. A fractured rock (full diameter) and dead oil were used for the experimental simulation of aquifer advance. Displacements were performed at reservoir conditions of high pressure and temperature (effective stress range 2000 psi < p < 7000 psi and 120 °C). The coreflooding was carried out in two phases, an effective stress phase in which the oil contained in the double porosity system was displaced, fractures are open and represent the preferential fluid flow paths in the rock. Phase 1 ends when only flow of water is recovered. In combination with effective porosity data, it was possible to estimate the remaining oil saturation in the double porosity. The second phase corresponds to the continuation of the coreflooding with high effective stress where the rock has primary porosity (pseudo-matrix) characteristics.