Open-Loop NMR Transmitter Distortion Correction
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Solution Overview
Problem
NMR systems face distortion issues in RF pulse sequences due to downhole conditions such as fluid impedance and temperature variations, leading to inaccurate NMR measurements, which are exacerbated by the complexity and noise introduced by closed-loop feedback systems.
Innovation Solution
An open-loop system that uses a sensor to measure parameters like temperature and quality factor to generate an input signal that corrects for distortions in the electromagnetic signal transmitted by the NMR logging tool, improving data accuracy without introducing noise or increasing system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If closed-loop feedback is used to correct RF pulse distortion, then measurement accuracy is improved, but system complexity and noise increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction signals in lookup tables before actual NMR measurements are performed. The system characterizes the borehole environment in advance, determines the appropriate RF pulse correction signals, and stores them for later retrieval during measurement, eliminating the need for complex real-time feedback processing while maintaining measurement accuracy
Solution Approach 2:
The patent uses copying by creating lookup tables that store pre-computed correction signals based on characterized borehole conditions. Instead of performing complex real-time calculations or using feedback loops, the system copies the appropriate correction signal from the lookup table based on matched borehole parameters, significantly reducing system complexity while preserving measurement precision
2Measurement precision
If closed-loop feedback is used to correct RF pulse distortion, then measurement accuracy is improved, but noise is introduced
Solution Approach 1:
The patent eliminates noise-generating feedback loops by performing all correction signal calculations in advance. The system characterizes the borehole environment beforehand, computes the necessary RF pulse corrections, and stores them in lookup tables. During actual measurements, the system simply retrieves pre-computed correction signals without introducing feedback-related noise
Solution Approach 2:
The patent avoids noise by copying pre-computed correction signals from lookup tables rather than generating them through real-time feedback processing. This approach retrieves stored correction data based on matched borehole parameters, eliminating the noise that would otherwise be introduced by feedback circuitry and real-time signal processing
3Object-affected harmful factors
If downhole conditions vary, then RF pulse distortion increases, but measurement adaptability decreases
Solution Approach 1:
The patent prepares for varying downhole conditions through preliminary characterization and creates lookup tables covering a range of borehole environments. When actual measurements are performed, the system quickly matches the current borehole conditions to the pre-characterized data and retrieves the appropriate correction signals, enabling rapid adaptation to different conditions without real-time complex processing
Solution Approach 2:
The patent handles varying downhole conditions by changing parameters in advance - characterizing different borehole environments and storing correction signals for various parameter combinations (fluid impedance, temperature, pressure). During measurement, the system adjusts by selecting the appropriate pre-computed correction signals based on matched parameters, enabling adaptability without real-time complex adjustments
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 approach mitigates distortions in NMR logging data, providing more accurate petrophysical property measurements by calibrating the NMR system based on measured parameters, thereby enhancing the precision of NMR data acquisition in downhole environments.
Implementation Method 1
measuring a parameter indicative of a property of the transmitter using a sensor in the wellbore
Implementation Method 2
applying the input signal to the transmitter to transmit the EM signal corrected for distortions
Implementation Method 3
Nuclear magnetic resonance (NMR) is used as a tool in a number of different technology areas to investigate different types of mediums. NMR can occur when the medium is subjected to a static magnetic field, B0, and to an oscillating magnetic field, B1
Data Source
AI summary
A method and system for transmitting an electromagnetic (EM) signal in a wellbore to improve an open loop system. The method comprises measuring a parameter indicative of a property of a transmitter using a sensor in the wellbore and generating an input signal for the transmitter based at least in part on the measured parameter to correct distortions exhibited by the output signal of the transmitter. The method comprises also comprises applying the input signal to the transmitter to transmit the EM signal corrected for distortions. The system comprises an antenna, a transmitter, a sensor, and a controller. The controller is configured and operable to generate an input signal for the transmitter based at least in part on the measured parameter to correct distortions exhibited by an output signal of the transmitter; and apply the input signal to the transmitter to transmit the EM signal corrected for the distortions.