ESTIMATION OF ABSOLUTE PERMEABILITY IN MICROCT IMAGES OF HIGHLY HETEROGENEOUS CARBONATE ROCKS (Atena Editora)

Abstract

: Carbonates rocks contain more than 50% of the world’s oil prove reserves. Hence, to consider proper strategies in oil recovery methods, the understanding of how fluid flows in such porous media has fundamental importance. Advances in X-ray microCT enable us to retrieve not only most of the details of the internal structure of rocks, but also simulated petrophysical properties. However, one single microCT image can be unable to sufficiently describe the wide range of pore sizes of carbonate rocks, specially the sub-resolution porosity (microporosity). To address this problem, we propose a study to assess the influence of the sub-resolution porosity on the fluid-flow and in the intrinsic permeability values, obtained from carbonate core-plug subsamples microCT images. Brinkman equation is used to model the fluid flow in the entire domain, covering the pores governed by the Stokes equation and the regions of the microporosity governed by Darcy flow (solved using the Finite Volume Method). Simulation results show that when connectivities among the voids are present and microporosity is considered, the value of permeability increases, but remains between the limits, i.e. when consider only the voids and the microporosity as voids. Furthermore, when the pore connectivity place through a microporosity’s region, it has an important role to estimate permeabilities.