Estimation of absolute permeability in microCT images of highly heterogeneous carbonate rocks

Resumo

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 struc-
ture 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 (mi-
croporosity). 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 con-
sidered, 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.