Influence of Key Parameters on the Fractal Dimension and Impact on Gas-Bearing Capacity: A Case Study from the Lower Shihezi Formation, Ordos Basin

作者：Lei Bao, Yuming Liu, Qi Chen, Zhanyang Zhang, Jiagen Hou · 发表于：Fractal and Fractional · 年份：2025 · DOI：10.3390/fractalfract9120799 · 被引用次数：2 · 研究领域：Hydrocarbon exploration and reservoir analysis、Enhanced Oil Recovery Techniques、CO2 Sequestration and Geologic Interactions

Pore–throat structure and gas distribution are critical factors in evaluating the quality of tight sandstone reservoirs and hydrocarbon resource potential. Twelve tight sandstone samples from the Lower Permian Shihezi Formation in Hangjin Banner, Ordos Basin, were selected for CTS, X-ray diffraction, HPMI, and gas displacement NMR analyses. By converting the T2 spectra into pore–throat distributions and applying fractal methods, we quantitatively analyzed the influences of multiple factors on gas distribution characteristics across different pore–throat sizes. The main results are as follows: All samples exhibit a three-stage pore–throat distribution, defining mesopores, micropores, and nanopores; quartz content mainly influences the fractal dimension of mesopores by enhancing structural stability and gas storage capacity, whereas clay minerals control the fractal characteristics of nanopores by increasing pore–throat complexity. An increase in clay mineral content increases the fractal dimension, indicating stronger reservoir heterogeneity and consequently poorer gas-bearing capacity. Larger pore–throat parameters (Rm, Sk, and Smax) correspond to lower fractal dimensions, indicating better connectivity and greater gas storage capacity. Among these factors, pore–throat parameters exert the most significant influence on the fractal dimensions of mesopores and micropores, jointly determining the overall connectivity and the upper limit of the reservoir’s gas-bearing capacity. T...