ANALYSIS OF FLUID TRANSPORT THROUGH POROUS MEDIA BY 2D NMR-EXCHANGE RELAXOMETRY

Abstract

Low field Nuclear Magnetic Resonance (NMR) relaxometry is an important technique to investigate fluid dynamics in porous media. The two- dimensional correlation Laplace NMR experiments acts an efficient tool to investigate exchange process in different pore classes in a porous media. In these experiments an initial NMR relaxation environment is correlated with a final relaxation environment of molecules migrating from one environment to the other during NMR mixing time im. In this work, T2-T2 relaxation exchange experiments were performed on saturated glass bead system in presence of the fluid flow at different flow rates and at a low and inhomogeneous magnetic field with a simple portable Halbach magnet at a proton Larmor frequency of 9.6 MHz. The Inverse Laplace transformation algorithm is used to analyze relaxation curves which yield T2—T2 exchange maps from which the exchange pathways between different relaxation sites could be achieved. These experiments revealed that exchange of fluid between different relaxation sites is the characteristic of the size and arrangement of the particles in a porous media. The nature and rate of fluid flow also have dominant effect on exchange phenomenon. The profiles help in quantization of exchange phenomenon as a function of peak shift.