Contributed review: nuclear magnetic resonance core analysis at 0.3 T

Area of Science:

• Geoscience
• Petrophysics
• Analytical Chemistry

Background:

• Nuclear Magnetic Resonance (NMR) is crucial for laboratory petrophysical analysis of reservoir core plugs and fluids.
• Low-field NMR magnet technology has been historically emphasized for well log calibration.
• There is a growing interest in utilizing stronger magnets to enhance reservoir sample studies beyond standard NMR measurements.

Purpose of the Study:

• To review the capabilities of an intermediate field (0.3 T) imaging magnet for reservoir core analysis.
• To highlight the advantages of intermediate field NMR for characterizing diverse rock types, including shales.
• To demonstrate the complementary role of intermediate field NMR to low-field instruments in core analysis and materials science.

Main Methods:

• Utilized a 0.3 T imaging magnet (12.9 MHz proton frequency) for reservoir core plug analysis.
• Acquired multidimensional imaging data.
• Performed quantitative estimation of porosity, saturation, and pore size distributions.
• Investigated the detection of lower gyromagnetic ratio nuclei and employed short probe recovery times.

Main Results:

• Achieved quantitative estimates of porosity and pore size distributions, particularly effective in carbonate samples.
• Demonstrated the suitability of the system for shale studies due to advanced imaging and detection capabilities.
• Generated quantitative porosity maps of rock plugs, offering insights not achievable with high-field medical scanners due to susceptibility contrasts.
• Presented example data illustrating the utility of intermediate field imaging.

Conclusions:

• Intermediate field NMR imaging instruments provide valuable quantitative data for reservoir core analysis.
• These systems complement low-field NMR by offering multidimensional imaging and enhanced characterization, especially for shales.
• The technology holds significant potential for both petrophysical studies and broader materials science applications.