Multifractal Parameters as Indicators of Pore Structure Heterogeneity in a Lower Cretaceous Limestone Reservoir (UAE)

Characterizing and predicting reservoir heterogeneity is essential for efficient hydrocarbon production. In this study, multifractal theory is employed, using both numerical and experimental data, to quantitatively describe the pore structure heterogeneity of a Lower Cretaceous limestone reservoir from the United Arab Emirates. Fractal dimensions derived from three-dimensional digital images show a strong correlation with high-pressure mercury injection (HPMI) measurements (R² = 0.69). Furthermore, both experimental and numerical fractal dimensions correlate well with HPMI-derived porosity. Multifractal parameters—including the non-uniformity degree of the pore structure (Δα), the asymmetry in the vertical axis (Δf(α)), the concentration of the pore size distribution (α₀), and the asymmetry in the horizontal axis (Rd)—calculated from digital and experimental data, are consistently correlated and demonstrate a robust ability to quantify sample heterogeneity. The ranges of these digital and experimental multifractal parameters provide an effective basis for distinguishing between homogeneous and heterogeneous samples.