NONDESTRUCTIVE, MOBILE NUCLEAR MAGNETIC RESONANCE TECHNOLOGY FOR GROUNDWATER EXPLORATION

The palm-size one-sided NMR probe is employed as a nondestructive mobile scanning tool to obtain information in-situ. It has been widely used for near-surface studies of arbitrarily large objects. Geophysical exploration such as groundwater and oil-well logging, contents of organic solids, and assessment of water in concrete bridge decks are some of the many successful applications of the technology. This technique utilizes the interaction of the hydrogen nuclei contained in the object (or sample) being investigated with the magnetic fields and low-powered radiofrequency irradiation. It makes use of the fact that hydrogen signals from molecules in different environment show different NMR relaxation properties. In groundwater exploration, this technique is useful in the search for oil and water in underground deposits, to determine water content, porosity, and permeability of aquifers. Other applications include but not limited to: examination of petrophysical properties (pore size distribution, wettability, tortuosity, permeability) of rock beds, coals, sediments, shale grains, etc; delineation between bound vs. movable fluids, and also capillary-bound vs. clay-bound water; analysis of fluid properties, such as viscosity and hydrogen index; and quick quantification of the soil moisture as a control of the ecosystem functions. Equivalent analysis can also be performed ex-situ using a bench-top low field NMR, which operates using the same principle as mobile NMR. In this presentation, the basic principle of NMR technology and its applications related to geological science will be elaborated. Possible new applications in near future will also be discussed.