New magnet array design for downhole NMR azimuthal measurement

Area of Science:

• Geophysics and Petrophysics
• Nuclear Magnetic Resonance (NMR) Well-Logging

Background:

• Low-field NMR well-logging typically assumes homogeneous formations for petrophysical analysis.
• Formation inhomogeneity can significantly impact the accuracy of downhole NMR imaging and hydrocarbon detection.
• Existing NMR imaging methods lack detailed azimuthal measurement capabilities to address formation heterogeneity.

Purpose of the Study:

• To design and implement a novel quadrupolar magnet array for azimuthal NMR measurements.
• To enhance the accuracy of downhole NMR imaging in heterogeneous formations.
• To improve the characterization of formation properties and oil/gas localization.

Main Methods:

• Development of a new quadrupolar magnet array using bread-shaped and hexangular magnets.
• Achieving a strong and homogeneous static magnetic field in the circumferential direction at greater depths of investigation (DOI).
• Integration of the quadrupolar magnet array with a coil array for azimuthal measurements.

Main Results:

• The new quadrupolar magnet array successfully generates a sufficiently strong and homogeneous static field.
• The system enables azimuthal measurements, providing detailed spatial information.
• Demonstrated potential to overcome limitations of traditional NMR well-logging in inhomogeneous formations.

Conclusions:

• The novel quadrupolar magnet array is effective for azimuthal NMR measurements in downhole formations.
• This technology offers improved accuracy for petrophysical parameter determination and hydrocarbon identification.
• The developed system represents a significant advancement in NMR well-logging for complex geological environments.