Nuclear Magnetic Resonance (NMR)

Borehole nuclear magnetic resonance (NMR) is unique because it directly senses the presence of water. As a result, borehole NMR can assess hydrologic properties such as porosity, water content, and bound and unbound water in porous materials. NMR data can also help understand the vertical distributions of water content and pore-size distribution. Technology advancements have reduced the size of NMR tools, making them more cost-effective for hydrological, environmental, geotechnical, and mining applications.

How does it work?

The borehole NMR logging process employs the principles of nuclear magnetic resonance to provide a detailed understanding of subsurface properties. This method involves analyzing the response of hydrogen nuclei within subsurface fluids to magnetic fields and radio frequency (RF) pulses. Upon removal of the RF pulse, the nuclei return to their equilibrium state, releasing energy that is detectable as an NMR signal. This signal provides invaluable information about the fluid and porous media in the subsurface.

  • Nuclear: Refers to the nucleus of an atom. In NMR, the interaction of atomic nuclei with magnetic fields is fundamental to the technique.
  • Magnetic: Relates to magnetic fields and the magnetic properties of atomic nuclei. An external magnetic field changes the energy states of the nuclei, making them detectable by NMR.
  • Resonance: Enables the detection and measurement of energy absorbed by the nuclei. The specific frequencies where resonance happens provide information about the local chemical environment of the nuclei, which helps in analyzing the sample.
  • Borehole NMR logging tools are deployed directly into boreholes, utilizing magnetic fields and RF pulses to investigate the surrounding geological formations. The process involves lowering a specialized NMR logging tool into the borehole on a wireline. As the tool is retrieved, it emits RF pulses and records the resultant NMR signals at various depths. This method allows for continuously profiling subsurface characteristics along the borehole, providing a detailed look at the geological structure and fluid distribution adjacent to the borehole.

    The time required for borehole NMR logging depends on several factors, including borehole depth, the desired resolution, and the type of NMR tool used. Typically, a borehole NMR survey can take a few hours to a full day. This efficient data collection process and the abundance of information provided by NMR signals make borehole NMR a valuable technique for rapid and comprehensive borehole analysis.

Applications of Borehole NMR

The borehole NMR system is widely used for geologic investigations providing detailed data for understanding subsurface conditions. It is particularly valued for its efficiency in coverage and field deployment times in geophysical investigations, making it a preferred choice for many large-scale applications.

Groundwater Exploration: Mapping Aquifers

Borehole NMR maps aquifers, providing data on their depth, extent, and properties. This information is crucial for aquifer evaluation, storage and recovery, saltwater intrusion, well-screen placement, and sustainability planning, especially in water-scarce areas.

Hydraulic Conductivity Estimates: Fluid Flow

Borehole NMR helps understand how easily fluids can flow through subsurface materials. These estimates are essential for groundwater models and are vital for groundwater management and engineering projects.

Environmental Applications: Detecting Contaminants and Monitoring Cleanup

Borehole NMR provides subsurface information for detecting contaminants and monitoring cleanup projects. It helps identify contamination plumes and can track their movement over time, aiding in groundwater flow modeling, remediation design, and delineation of flow paths and barriers.

Engineering Applications: Hazard Assessment

Borehole NMR can give insight into understanding subsurface information for land suitability related to construction projects. This information helps identify locations for foundations and potential hazards. It also supports soil stability assessments, liquefaction risk analysis, dam and levee inspection, and foundation dewatering, aiding engineers in designing safe and stable structures while avoiding construction risks.

Mining

Dewatering

Borehole NMR can help understand methods for managing and removing water from mining sites, preventing flooding, and ensuring safe mining operations.

Waste Rock and Tailings Stability

Borehole NMR can help assess the stability of waste rock and tailings, monitor conditions to prevent collapses or leaks, and help determine environmental safety and stability.

In-situ Leaching and Heap Leaching

Borehole NMR enhances leaching processes by providing data on their effectiveness and impact, improving efficiency and environmental management in in-situ leaching and heap leaching operations.

Environmental Impact Assessment

Borehole NMR helps evaluate subsurface conditions and potential hazards, ensuring mining activities comply with environmental regulations.

Technical Specifications

The borehole NMR system is designed for detailed subsurface mapping. It features advanced high-resolution transmitters and receivers for high-quality data collection. One of the significant advantages of borehole NMR is its ability to provide subsurface geophysics data quickly and cost-effectively, particularly beneficial for large-scale surveys, offering detailed 3D geological mapping capabilities that are better than many traditional methods. HydroGEOPHYSICS, Inc. (HGI) offers comprehensive borehole NMR services, from initial consultation to data acquisition and processing. Our team is ready to provide high-quality, reliable geophysical surveys tailored to your needs.

Partner with HGI: Your Subsurface Exploration Experts

HydroGEOPHYSICS, Inc. (HGI) is not just a service provider; we are your partner in unlocking the secrets of the subsurface. Our borehole NMR logging services stand at the intersection of innovation and practical application, offering a window into the subsurface with precision and reliability.

Learn the Applications of Borehole NMR