Multi-Azimuth NMR Logging Probe with Independent Antennas
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Solution Overview
Problem
Nuclear magnetic resonance logging instruments are limited to detecting signals only in radial and axial depth dimensions, lacking the capability to detect signals in the circumferential multi-azimuth sensitive area.
Innovation Solution
The instrument features a probe with multiple main magnets and antennas arranged in a specific configuration, allowing for independent feeding of antennas to achieve mono-azimuth, multi-azimuth, or omni-directional detection by exciting different antennas, thereby enhancing circumferential recognition and enabling three-dimensional stratum detection without increasing the radial dimension of the probe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a column-shaped magnet with surrounding antenna is used to excite polarized stratum regions all around the borehole, then the nuclear magnetic resonance logging instrument can perform multi-frequency multi-slice measurement without detecting blind zones, but it can only detect signals in radial and axial dimensions without circumferential multi-azimuth detection capability
Solution Approach 1:
The patent divides the single surrounding antenna into multiple independent antennas arranged at different azimuth angles around the borehole. Each antenna is associated with specific main magnets to create independent detection channels for different azimuth directions, enabling segmentation of the detection function to capture circumferential multi-azimuth signal information that was previously lost
Solution Approach 2:
The patent transitions from two-dimensional detection (radial and axial dimensions only) to three-dimensional detection by adding circumferential azimuth dimension. Multiple antennas are positioned at different angular positions around the borehole, creating detection channels that span all three spatial dimensions and enabling comprehensive 3D stratum characterization
2Adaptability or versatility
If multiple main magnets and independently fed antennas are arranged in specific configurations, then circumferential multi-azimuth detection capability is achieved, but the device complexity increases
Solution Approach 1:
The patent designs the probe framework and magnet-antenna assemblies to serve multiple functions: each main magnet-antenna pair can independently detect signals from different azimuth directions, and the system can operate in various detection modes (mono-azimuth, multi-azimuth, or omni-directional) by selectively activating different antenna groups, reducing overall system complexity through functional integration
Solution Approach 2:
The patent employs a nested structural arrangement where multiple main magnets are positioned above and below the shielding layer within the probe framework, with antennas arranged around the magnets. This compact nested configuration allows multiple detection elements to be integrated within a constrained radial dimension while maintaining their independent functionality
3Adaptability or versatility
If the radial dimension of the probe is increased to accommodate multiple magnets and antennas for multi-azimuth detection, then circumferential detection capability is improved, but the downhole detection may be affected and cost increases
Solution Approach 1:
The patent resolves the radial dimension constraint by utilizing the axial dimension more effectively. Multiple main magnets are positioned at different axial locations (above and below the shielding layer), and antennas are arranged around these magnets. This axial distribution allows multiple azimuth detection channels to be created without proportionally increasing the radial dimension, maintaining compact probe geometry suitable for downhole deployment
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves the circumferential detection capability, allowing for three-dimensional stratum information acquisition (radial, axial, and circumferential) while maintaining cost-effectiveness and unaffected downhole detection.
Implementation Method 1
the magnet can form a static magnetic field for polarizing spinning hydrogen protons
Implementation Method 2
the antenna can emit a radio frequency field for turning the spinning hydrogen protons, after the radio frequency field is removed, the spinning hydrogen protons start to precess along the static magnetic field, thus generate nuclear magnetic resonance inductive signals
Data Source
AI summary
The present invention provides a multi-azimuth nuclear magnetic resonance logging instrument and an antenna excitation method, the nuclear magnetic resonance logging instrument includes: a probe framework and a shielding layer arranged in the probe framework; a plurality of main magnets are provided above and below the shielding layer, respectively; central axes of the main magnets are parallel with each other, and distances between the central axes of each of the main magnets and a central axis of the probe framework are the same; a distance between central axes of any two main magnets is not smaller than a first preset value; and an antenna is provided at outer side of each main magnet, and a plurality of the antennas are fed independently. In the present invention, circumferential recognizing capability of the nuclear magnetic resonance logging instrument can be improved and three-dimensional (radial, axial and circumferential) stratum detection can be achieved.