Switched-Field Surface NMR for Enhanced Detection andResolution of Shallow Groundwater

This proposal addresses the challenge of mapping groundwater and hydrogeologic parameters in the subsurface, with a focus on improving sensitivity and spatial resolution for shallow groundwater targets. We will apply imaging methodologies at the core of medical MRI to efficiently map shallow groundwater and hydrogeologic properties at improved resolution. Conventional surface NMR has been proven as a powerful non-invasive technique for coarse groundwater imaging. The method is limited, however, by simplistic imaging protocols. To enhance sensitivity and spatial resolution, we will introduce “switched-field” NMR. This new paradigm combines gradient and prepolarization fields to allow localization of signals based on their frequency and phase response and will increase the signal-to-noise ratio for shallow water. In addition to improving resolution, these approaches will also accelerate measurement speed allowing the technology to be applied in a wider range of environments and markets. The Phase 1 work will establish the feasibility of gradient imaging and the combined use of prepolarization fields. Numerical simulations will be used to refine optimal survey geometries timing parameters and to quantify the improvements of switched-field surface NMR over conventional surface NMR. The simulations will also identify requirements for hardware capable of implementing these measurement schemes. Prototype electronics will be developed in the laboratory as modular add-ons to a robust existing framework of surface NMR electronics. A basic implementation of the technology will be field tested by the end of the Phase I period. Concurrent with technical development, we will also research the commercialization and market potential for this technology through interactions with existing government and industry customers. Completion of this technology will deliver a powerful groundwater imaging product for commercial sale, rental, and/or services in the environmental, geotechnical, and subsurface research markets. This technology will be of value to companies, governments, and public agencies facing problems such as groundwater contamination, dewatering for geotechnical engineering, and permafrost mapping. The ability to image at high-resolution in with reduced survey times will improve the reliability of subsurface models, reduce site characterization costs, support informed decision making. In turn, this technology will improve project efficiency, reduce risk, and result in improved outcomes.