Downhole NMR Array Antenna for 3D Signal Detection
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Solution Overview
Problem
Nuclear magnetic resonance logging tools lack the capability for signal detection in circumferentially multi-directional sensitive regions, limiting their ability to perform comprehensive three-dimensional scanning.
Innovation Solution
A radio frequency antenna receiving device with an array antenna system that includes multiple antenna units, each corresponding to different circumferentially sensitive regions, allowing for selective signal reception and amplification, and connected to an antenna interface circuit, receiving and amplifying circuit, analog-to-digital conversion circuit, and control circuit for comprehensive signal collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single antenna surrounds the magnet to perform 360° excitation, then there is no detection blind region around the wellbore, but the measured signal can only be an average signal of signals in the 360° stratum without circumferential multi-directional detection capability
Solution Approach 1:
The single antenna is segmented into multiple antenna units (at least four) arranged in an array, with each unit responsible for detecting signals from specific circumferential directions. This segmentation allows the system to maintain 360° coverage while achieving direction-specific detection precision by assigning each antenna unit to monitor a particular angular sector.
Solution Approach 2:
The detection capability is extended from two dimensions (radial and axial) to three dimensions by adding circumferential angular resolution. The array antenna configuration enables the system to resolve signals not only in radial and axial directions but also in circumferential directions, achieving true three-dimensional scanning capability.
2Adaptability or versatility
If multiple antenna units are used to achieve circumferential multi-directional detection, then three-dimensional scanning capability is improved, but device complexity increases
Solution Approach 1:
Multiple antenna units share common functional circuits including the receiving and amplifying circuit, analog-to-digital conversion circuit, and signal collecting circuit. This multi-functionality approach allows each antenna unit to utilize the same signal processing resources, reducing overall device complexity while maintaining three-dimensional scanning capability.
Solution Approach 2:
The patent merges the signal processing functions for multiple antenna units into shared circuits. The receiving and amplifying circuit, analog-to-digital conversion circuit, and signal collecting circuit serve all antenna units collectively, consolidating what could have been separate independent systems into a unified structure that reduces complexity.
3Productivity
If traditional radial and axial detection is used, then device structure is simple, but comprehensive three-dimensional scanning capability is limited
Solution Approach 1:
The detection space is segmented into multiple circumferential sectors, with each antenna unit monitoring a specific angular range. This segmentation enables comprehensive three-dimensional scanning by dividing the 360° circumferential space into manageable sectors that can be detected independently and then combined.
Solution Approach 2:
The system transitions from two-dimensional detection (radial and axial only) to three-dimensional detection by incorporating circumferential angular resolution. This dimensional extension is achieved through the array antenna configuration that provides sensitivity in the circumferential direction while maintaining radial and axial detection capabilities.
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
Enables three-dimensional signal detection in axial, radial, and circumferential depth dimensions, enhancing the capability of nuclear magnetic resonance imaging by allowing for multi-directional signal detection and reducing device size and energy consumption.
Implementation Method 1
Nuclear Magnetic Resonance (NMR) phenomenon was discovered in 1946... After the radio frequency field is removed, the spin hydrogen proton begins to precession along the static magnetic field and thereby a nuclear magnetic resonance sensing signal is generated
Implementation Method 2
a receiving and amplifying circuit for amplifying the echo signal
Implementation Method 3
an analog-to-digital conversion circuit for converting an analog signal into a digital signal
Data Source
AI summary
Provided is a radio frequency antenna receiving method and device for a downhole three-dimensional scanning nuclear magnetic resonance imager. The device comprises: an array antenna for receiving an echo signal, an antenna interface circuit, a receiving and amplifying circuit for amplifying the echo signal, an analog-to-digital conversion circuit, a signal collecting circuit and a control circuit, which are sequentially connected; the array antenna comprises N antenna units, where N≥4; four ports of the control circuit are respectively connected to the antenna interface circuit, the receiving and amplifying circuit, the analog-to-digital conversion circuit and the signal collecting circuit so as to control them, and the control circuit is connected to a logging ground acquisition system; the antenna interface circuit selects one antenna unit in the array antenna. The method and device of the present invention can perform signal detection in a circumferentially multi-directional sensitive region.