Representative Elementary Volume of Rock Using X-Ray Microcomputed Tomography: A New Statistical Approach

Abstract

Rock heterogeneity is a key parameter influencing a range of rock properties such as fluid flow and geomechanical characteristics. The previously proposed statistical techniques were able to rank heterogeneity on a qualitative level to different extents; however, they need to select a threshold value for determination of representative elementary volumes (REV), which in turn makes the obtained REV subjective. In this study, an X-ray microcomputed tomography (μCT) technique was used to obtain images from different porous media. A new statistical technique was then used to compute REV, as a measure of heterogeneity, without the necessity of defining a threshold. The performance of the method was compared with other methods. It was shown that the calculated sum of the relative errors of the proposed method was lowest compared to the other statistical techniques for all tested porous media. The proposed method can be applied to different types of rocks for more accurate estimation of a REV.

Multiple Cubes Growth Algorithms for Simple Representative Elementary Volume Determination on 3D Binary Images

“…The REV size directly impacts the level of detail captured in analyses, and selecting an inappropriate value may result in misleading or inaccurate representations of the porous medium's behavior. A REV that is too large may oversimplify the material, neglecting crucial heterogeneity, while a REV that is too small may overly complicate the analysis, introducing noise from local fluctuations [22]. Consequently, finding the balance between these extremes is paramount to achieving meaningful results.…”