Nuclear magnetic resonance imaging for the characterization of liquids in porous media
NMR technique has proved to be a valuable non-invasive technique for probing porous media. The NMR study of the relaxation, liquid flow, and susceptibility effect in porous media will be discussed. The T[sub 1] and T[sub 2] relaxation times in porous media have been of great interest in the field of petrophysics and biology. The relaxation behavior can be used as a fingerprint of a system, or provide information on some other parameters which can not be easily measured. The authors investigate the behavior of the T[sub 1] and T[sub 2] relaxation in two types of media: A sedimentary rock like, and a tissue like medium. The two site relaxation process can be used to explain the relaxation behavior in both media. The possible explanation for the relaxation mechanism is discussed. Liquid flow in porous media has become a significant topic in medical imaging, because the quantification of the microcirculatory flow can provide the functional status of the system. The NMR measurement of fluid in a porous medium will be attenuated by the random directional motion of the fluid. A method based on a statistical model for the fluid in the porous medium is proposed to study this phenomenon. By means of the spin phase analysis technique, the NMR signal reduction due to flow in a gel bead phantom can be successfully estimated. The field inhomogeneity effect is another important topic for the study of porous media by NMR techniques. The internal heterogeneous field is usually arising from the susceptibility differences between the solid grains and the liquids in the porous medium. The authors propose a method to study the effect of susceptibility on the NMR flow measurement of a glass bead phantom, a porous medium with large susceptibility variation. A physical model is developed to simulate the paths of the moving spins and the local magnetic field distribution in the medium. The signal intensity can then be estimated by using the spin phase analysis technique.
- Research Organization:
- California Univ., Irvine, CA (United States)
- OSTI ID:
- 7295855
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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