Advanced nuclear magnetic resonance (NMR) imaging methodologies have
been developed to determine porous media properties associated with fluid flow processes.
This dissertation presents the development of NMR experimental and analysis
methodologies, called NMR probes, particularly for determination of porosity, permeability,
and pore-size distributions of porous media while the developed methodologies
can be used for other properties.
The NMR relaxation distribution can provide various information about porous
systems having NMR active nuclei. The determination of the distribution from NMR
relaxation data is an ill-posed inverse problem that requires special care, but conventionally
the problem has been solved by ad-hoc methods. We have developed a new
method based on sound statistical theory that suitably implements smoothness and
equality/inequality constraints. This method is used for determination of porosity
distributions. A Carr-Purcell-Meiboom-Gill (CPMG) NMR experiment is designed
to measure spatially resolved NMR relaxation data. The determined relaxation distribution
provides the estimate of intrinsic magnetization which, in turn, is scaled to
porosity.
A pulsed-field-gradient stimulated-echo (PFGSTE) NMR velocity imaging experiment
is designed to measure the superficial average velocity at each volume element. This experiment measures velocity number distributions as opposed to the average
phase shift, which is conventionally measured, to suitably quantify the velocities
within heterogeneous porous media. The permeability distributions are determined
by solving the inverse problem formulated in terms of flow models and the velocity
data. We present new experimental designs associated with flow conditions to enhance
the accuracy of the estimates. Efforts have been put forth to further improve
the accuracy by introducing and evaluating global optimization methods.
The NMR relaxation distribution can be scaled to a pore-size distribution once
the surface relaxivity is known. We have developed a new method, which avoids
limitations on the range of time for which data may be used, to determine surface
relaxivity by the PFGSTE NMR diffusion experiment.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4899 |
| Date | 25 April 2007 |
| Creators | Uh, Jinsoo |
| Contributors | Slattery, John C., Watson, A. Ted |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 4812935 bytes, electronic, application/pdf, born digital |
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