D–T2 correlation using the inhomogeneity of single sided NMR devices

• New method to measure D-T2 maps using single-sided NMR devices.
• Method works for non-uniform field gradients.
• Can be used with single-sided NMR devices of different designs.
• Method can be very useful for low-field and well-logging applications.

Single-sided NMR systems have become ubiquitous in industry and laboratory environments due to their low cost, low maintenance and capacity to evaluate quantity and quality of Hydrogen based materials. The performance of such devices has improved significantly over the last decade, providing increased field homogeneity, field strength and even controlled static field gradients. For a class of these devices, the configuration of the permanent magnets provides a linear variation of the magnetic field and can be used in diffusion measurements. However, magnet design depends directly on its application and, according to the purpose, the field homogeneity may significantly be compromised. This work introduces a new approach that extends the usability of diffusion-editing CPMG experiments to NMR devices with highly inhomogeneous magnetic fields, which do not vary linearly in space. Here we propose a method to determine a custom diffusion kernel based on the gradient distribution, which can be seen as a signature of each NMR device. This new diffusion kernel is then utilised in the 2D inverse Laplace transform (2D ILT) in order to determine diffusion-relaxation correlation maps of homogeneous multi-phasic fluids.

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