Multiscale NMR Characterization in Shale: From Relaxation Mechanisms to Porous Media Research Frontiers

ABSTRACT Nuclear magnetic resonance (NMR), as an advanced non‐destructive and rapid measurement technology, has shown unique advantages in the evaluation of unconventional shale reservoirs. This paper systematically introduces the fundamental principles of NMR spectroscopy and relaxation theory in porous media and comprehensively analyzes the experimental techniques and analytical methodologies for NMR and magnetic resonance imaging (MRI) applications in shale characterization. The content aims to provide substantive reference value for researchers and practitioners engaged in shale NMR investigations. Notably, despite existing technical challenges in expository relaxation mechanisms and capturing nanoscale pore signals within shale matrices, NMR applications present novel possibilities for developing emerging research frontiers. For instance, there is significant synergy between NMR technology and emerging fields such as supercritical CO 2 enhanced recovery, carbon capture, utilization and storage (CCUS), and underground hydrogen storage. This paper methodological framework exhibits extensibility to studies of tight sandstones, hydrate‐bearing sediments, and other porous media systems, thereby offering cross‐disciplinary technical support for establishing carbon neutrality‐oriented energy development paradigms.