Rock permeability measurements are generally conducted on core samples in centi-meters scale. Normally, the permeability can only be measured in one direction. Anisotropy of permeability can be obtained by measuring permeability of the other direction from different core samples. Using digital images data, such as that produced by micro-CT scanner, permeability of rock can be estimated in many directions more easily.
In this research, the permeability of reservoir X was estimated from Micro-CT data using Lattice Boltmann method, Kozeny-Carman approach and renormalization group technique. The degree of anisotropy was obtained from the ratio of permeability in different directions.
The sample was scanned using Micro-CT scanner Skyscan 1173 with X-ray source of 130 kV 60 A. The reconstructed images have resolution of 7.5 m/pixel and then cropped into box shaped with dimension of 2563 voxel (19203 m3). By performing image analysis, we obtain the value of porosity is about 18.48%. Using Lattice Boltzmann method, the anisotropy permeability, kx/kz and ky/kz, are about 1.23 and 1.08, and using Kozeny-Carman approach, 1.07 and 1.00. Estimation of effective permeability using renormalization group shows that the effective permeability is less than the calculated permeability. From this research, we can conclude that the images produced by micro-CT can be quite useful to be utilized for analysis of reservoir rock permeability.
Keyword : permeability, anisotropy, Kozeny-Carman, Lattice Boltzmann, renormalization
Authors : Z. Irayani, U. Fauzi, S. Viridi, B. Priadi