Changing the resonant nucleus by altering the static field, compensation of γ and B effects in T and T* measurements of porous media.

Multinuclear H, C, and Na magnetic resonance (MR) has many advantages for studying porous media systems containing hydrocarbons and brine. In recent work, we have explored changing the nucleus measured, keeping the Larmor frequency constant, by changing the static magnetic field B. Increasing the static B field distorts the field in the pore space due to susceptibility mismatch between the matrix and pore fluid.

Selective enhancement of H signal from water and oil in porous media at low field with Overhauser DNP.

In porous media MR studies, discriminating between oil and water presents a challenge because MR lifetimes are often similar and spectra overlap. Low saturations might suggest an experimental strategy of increasing the static field for increased sensitivity, but susceptibility effects are exacerbated at higher field. Overhauser dynamic nuclear polarization, effective at low static field, was employed with water and oil-soluble nitroxide to selectively enhance water and oil signals.

The matrix pencil as a tunable filter.

Despite inherent sensitivity constraints, nuclear magnetic resonance (NMR) plays an indispensable role in probing molecular structures and dynamics across scientific disciplines. Remarkably, while extensive efforts have targeted instrumental and experimental sensitivity improvements, comparatively little focus has been dedicated to sensitivity enhancement through signal analysis. Amidst this present gap, the matrix pencil method (MPM) has emerged as a versatile algorithm that offers tunable filtering and phasing capabilities.

Fast spin echo MRI of reservoir core plugs with a variable field magnet.

Fast Spin Echo MRI is now widely employed in biomedicine for proton density and T contrast imaging. Fast Spin Echo methods provide rapid data acquisition by employing multiple echoes to determine multiple k-space lines with single excitations. Due to the multi-exponential behavior of T in typical porous media, and the strong dependence of T on the details of the experiment, acquiring a proton density image with Fast Spin Echo methods requires favorable sample and acquisition parameters.

monitoring of mechanochemical MOF formation by NMR relaxation time correlation.

In this paper, we present a new approach to monitoring mechanochemical transformations, based on a magnetic resonance (MR) method in which relaxation time correlation maps are used to track the formation of the popular metal-organic framework (MOF) materials Zn-MOF-74 and ZIF-8. The two-dimensional (2D) relaxation correlation measurement employed yields a spectrum which visually and analytically identifies different H environments in the sample of interest. The measurement is well-suited to analyzing solid mixtures, and liquids, in complex systems.