Pore Structure Characterization of Jurassic Sandstones in the Northeastern Ordos Basin: An Integrated Experimental and Inversion Approach

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Detalles Bibliográficos
Publicado en:	Minerals vol. 15, no. 5 (2025), p. 547
Autor principal:	Yin Haiyang
Otros Autores:	Chen Tongjun, Li, Yueyue, Xu Haicheng, Li, Wan
Publicado:	MDPI AG
Materias:	Ordos Basin China Mercury Parameters Calcite S waves Clay minerals X-ray diffraction Wave velocity Sandstone Carbon dioxide Structural analysis P waves Nuclear magnetic resonance > NMR Porosity Microstructure Velocity Wave diffraction Modulus of elasticity Experiments Poisson's ratio Jurassic S-waves Acoustic velocity Coal mining Spectra Parameter sensitivity Aspect ratio Lithology Mineralogy Aquifers Geology Research methodology Hazard mitigation Physics Sedimentary rocks Permeability Diagenesis Nuclear magnetic resonance Acoustics Carbon capture and storage
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Descripción
Resumen:	Although Mercury Intrusion Porosimetry (MIP) and Nuclear Magnetic Resonance (NMR) are widely used for pore characterization, their effectiveness is fundamentally constrained by theoretical limitations. This study investigated the pore structure characteristics of coal-bearing sandstones from the northeastern Ordos Basin using an integrated approach combining experimental measurements and model-based inversion. The experimental measurements comprised a stress-dependent acoustic velocity test (P- and S-wave velocities), X-ray diffraction (XRD) mineralogical analysis, and NMR relaxation T2 spectra characterization. For model-based inversion, we developed an improved Mori-Tanaka (M-T) theoretical framework incorporating stress-sensitive pore geometry parameters and dual-porosity (stiff/soft) microstructure representation. Systematic analysis revealed four key findings: (1) excellent agreement between model-inverted and NMR-derived total porosity, with a maximum absolute error of 1.09%; (2) strong correlation between soft porosity and the third peak of T2 relaxation spectra; (3) stiff porosity governed by brittle mineral content (quartz and calcite), while soft porosity showing significant correlation with clay mineral abundance and Poisson’s ratio; and (4) markedly lower elastic moduli (28.78%–51.85%) in Zhiluo Formation sandstone compared to Yan’an Formation equivalents, resulting from differential diagenetic alteration despite comparable depositional settings. The proposed methodology advances conventional NMR analysis by simultaneously quantifying both pore geometry parameters (e.g., aspect ratios) and the stiff-to-soft pore distribution spectra. This established framework provides a robust characterization of the pore architecture in Jurassic sandstones, yielding deeper insights into sandstone pore evolution within the Ordos Basin. These findings provide actionable insights for water hazard mitigation and geological CO2 storage practices.
ISSN:	2075-163X
DOI:	10.3390/min15050547
Fuente:	ABI/INFORM Global