The Applications of NMR Relaxometry, NMR Cryoporometry, and FFC NMR to Nanoporous Structures and Dynamics in Shale at Low Magnetic Fields

Shale gas and oil have increasingly become a very important unconventional energy resource. As such, it is critical to characterize the porous structure and surface dynamics such as microwettability and diffusion, for the estimation and recovery of these unconventional resources. Due to the salient nanoporous structures present in shales, nuclear magnetic resonance (NMR) may currently be the only efficient and powerful tool for investigating and characterizing the nanoporous structures and dynamics in shales. This review discusses various NMR methods including NMR relaxometry, NMR cryoporometry, and fast field cycling (FFC) NMR and identifies the merits and limitations of these approaches. The review also identifies fallacies associated with such applications often seen in the literature. The potential of NMR can be exploited further as the methods used here for unconventional energy resources can also be applied to other intriguing porous media.