Exploring for the Future – Surface Nuclear Magnetic Resonance (SNMR) method

Exploring for the Future (EFTF) is an eight year, $225 million Australian Government funded program which commenced in 2016. The program is delivering new geoscience data, knowledge and decision support tools to support increased industry investment and sustainable economic development across Australia. Further detail is available at http://www.ga.gov.au/eftf. The program’s objective over the four years from 2016-2020 was to provide a holistic picture of the potential mineral, energy and groundwater resources in northern Australia. Groundwater is a critical resource that accounts for most water used across northern Australia. The groundwater component of the EFTF program focused on addressing groundwater resource knowledge gaps, to support future opportunities for economic development via irrigated agriculture, extractive industries and increased security of community water supplies. Through collaboration with State and Territory partners, the program undertook targeted regional investigations of groundwater systems and assessments of groundwater potential more broadly across the region. The program's activities, implemented by Geoscience Australia, involved application of innovative geoscience tools to collect, integrate and analyse a range of data. It includes geological and hydrogeological data, airborne and ground-based geophysical and hydrogeochemical surveys, remote sensing data as well as stratigraphic drilling. The new data and better understanding of groundwater systems also helps inform decision making about groundwater use to protect environmental and cultural assets. These outcomes strengthen investor confidence in resources and agricultural projects by de-risking groundwater in northern Australia. Surface nuclear magnetic resonance (SNMR) is an electrical, geophysical technique that was adapted from magnetic resonance imaging techniques used in the medical field. This technique is gaining prominence in groundwater studies as it can be used to detect the presence of water and estimate hydraulic properties in the top 100m of subsurface. SNMR data can be acquired rapidly, cheaply and non-invasively. This is advantageous in Australian groundwater studies where drilling is often expensive and logistically challenging due to land access issues and environmental regulations. For the reasons described above SNMR has been one of the most important groundwater datasets acquired as part of the EFTF program. The derived estimates of water content have been used for several applications including; estimating hydraulic conductivity, mapping the water table surface, and defining aquifer architecture. The purpose of this document is to provide a description of the SNMR method and how the data are acquired, processed and inverted as part of the EFTF program.