Experimental study on electrical dispersion in 3D printed resin cores reveals pore and fluid property mechanisms

Quantitative analysis of the relationship between rock physical parameters (pore structure, fluid properties) and electric dispersion response is crucial for well-log interpretation and reservoir evaluation. However, the strong heterogeneity inherent in natural rocks, resulting from complex diagenetic processes, poses significant challenges in establishing suitable pore structure parameters for assessment. This study employed light-curing 3D printing technology to fabricate core samples with explicitly defined pore structures and a resolution of 49.8 μm. Initially, the complex resistivity dispersion properties of these 3D-printed cores were compared with those of heterogeneous sandstone and coal samples. While exhibiting similar dispersion trends, the resistivity magnitude and polarization frequency demonstrated marked variations attributable to differences in pore structure. Subsequently, experimental investigations were conducted over a frequency range of 40 Hz to 110 MHz to quantitatively analyze the influence of porosity, saturation, salinity, and pore-throat structure on the complex resistivity dispersion of the 3D-printed cores. Resistivity and polarization frequency exhibit a monotonic relationship with porosity, whereas they conform to a power-law relationship with respect to saturation, salinity, and pore-throat structure. Notably, variations in pore-throat diameter and length exert a significant influence on the complex resistivity dispersion properties, underscoring the critical importance of pore structure. As a pioneering effort in the literature, this study demonstrates that 3D printing technology represents a novel, feasible, and alternative laboratory testing method within the domain of electrical rock physics. Meanwhile the quantitative description of rock physical parameters and electric dispersion response can provide new ideas for geological exploration and energy development.