Distinguishing Geometric and Apparent Relaxation–Response Fractal Parameters in Fuyu Formation Tight–to–Low–Permeability Sandstones: A Comparative MICP–NMR Framework

作者：Mengying Wang, Chengwu Xu, T J Li, Hongyu Li, Hao Wang · 发表于：Fractal and Fractional · 年份：2026 · DOI：10.3390/fractalfract10080507 · 研究领域：Hydrocarbon exploration and reservoir analysis、NMR spectroscopy and applications、Enhanced Oil Recovery Techniques

Fractal analysis has been widely applied to characterize the complexity of pore systems in tight sandstone reservoirs. However, fractal parameters derived from different experimental techniques are frequently interpreted without sufficient consideration of their distinct physical meanings. In this study, tight sandstones from the Fuyu Formation in the Songliao Basin were investigated using cast thin sections, scanning electron microscopy, high–pressure mercury intrusion porosimetry, and nuclear magnetic resonance. The objective was to establish a comparative interpretation framework that distinguishes capillary–pressure–controlled geometric fractal dimensions from NMR–derived apparent relaxation–response fractal parameters (ARR fractal parameters). The pore–throat system is dominated by medium– to fine–sized throats, with the dominant pore–throat radii concentrated between 0.05 and 0.15 μm. Mercury–intrusion–derived fractal parameters primarily characterize the geometric heterogeneity of relatively large and fine pore–throat systems, whereas NMR–derived parameters mainly reflect the apparent relaxation response associated with pore–scale fluid occurrence rather than strict geometric complexity. In the present MICP–NMR subset, comparative regression trends indicate that the geometric fractal parameter representing fine pore throats is more responsive to median pore–throat radius and movable–fluid saturation, whereas the NMR–derived apparent relaxation–response parameter associ...