Fundamentals of Fluid Flow in Porous Media

Chapter 3

Diffusion Coefficient: Measurement Techniques

NMR Method

Nuclear Magnetic esonance (NMR) was mainly developed for chemical-physical-medical use. The principle of this method is to calculate the density of hydrogen protons.

NMR is a phenomenon, which occurs when the nuclei of certain atoms are immersed in static magnetic field and exposed to a second oscillating magnetic field. Some nuclei experience this phenomenon, and others do not, depending on atomic composition. Based on the nature of magnetic resonance, NMR measurement can be made on any nucleus that has an odd number of protons or neutrons or both, such as the nucleus of hydrogen (H), carbon (C), and sodium (Na). For most of the nuclei found in earth formations, the nuclear magnetic signal induced by external magnetic fields is too small to be detected with NMR device such as borehole NMR logging tool.  However hydrogen as the main atom of water and other hydrocarbon molecules produces a strong signal. So the strength of the signal could be used as a scale of the existing hydrogen.