Randomizing Pulse Module for NMR Residual Magnetization Removal
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Solution Overview
Problem
Nuclear magnetic resonance (NMR) data sets obtained during well logging often contain inaccuracies due to residual magnetization, which affects the interpretation of formation properties such as porosity, as existing methods only partially suppress remnant magnetization, leading to inaccuracies in NMR data analysis.
Innovation Solution
Incorporating a randomizing pulse module that outputs a randomizing pulse sequence to effectively remove net detected residual magnetization, allowing for accurate NMR data analysis by ensuring the magnetization sums to zero, thereby aligning with the on-resonance magnetization model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If refocusing pulse sequences are used to measure NMR data, then relaxation times can be measured, but residual magnetization accumulates and causes measurement inaccuracies
Solution Approach 1:
A randomizing pulse is applied periodically between refocusing pulse sequences to disrupt and remove accumulated residual magnetization. This periodic intervention prevents the build-up of steady-state magnetization that would otherwise contaminate subsequent NMR measurements, thereby maintaining measurement accuracy throughout the logging operation.
Solution Approach 2:
The residual magnetization, which is normally a harmful artifact degrading measurement quality, is converted into a manageable condition by applying a randomizing pulse that selectively removes it. The harmful steady-state magnetization build-up is transformed into a controlled reset process, allowing accurate NMR data acquisition to continue without degradation.
2Productivity
If multiple refocusing pulse sequences are applied, then more NMR data can be collected, but residual magnetization builds up and reduces data quality
Solution Approach 1:
The randomizing pulse is inserted at regular intervals between refocusing pulse sequences, enabling continuous high-rate data collection while periodically clearing residual magnetization. This maintains measurement precision across multiple sequences without sacrificing productivity, as the randomizing pulse operation is brief and does not significantly extend total measurement time.
3Device complexity
If no randomizing pulse is applied, then the measurement process is simpler, but residual magnetization causes errors in porosity determination
Solution Approach 1:
The randomizing pulse acts as an intermediary element between refocusing pulse sequences, serving as a bridge that removes residual magnetization without significantly complicating the overall measurement system. This single additional pulse component effectively eliminates porosity measurement errors while maintaining relative simplicity in the pulse sequence design.
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
The use of randomizing pulses ensures accurate NMR data sets by eliminating residual magnetization, improving the accuracy of porosity determination and other formation properties, reducing errors associated with steady-state magnetization build-up.
Implementation Method 1
nuclear magnetic resonance (NMR) operation
Implementation Method 2
remove a net detected residual magnetization
Data Source
AI summary
In one aspect, a nuclear magnetic resonance (NMR) system includes a transmitter to output a main refocusing pulse sequence and at least one subsequent refocusing pulse sequence into a zone of interest, a randomizing pulse module to output a randomizing pulse into the zone of interest to remove a net detected residual magnetization, and a receiver to output an NMR data set from the zone of interest. In another aspect, a method of generating a nuclear magnetic resonance (NMR) data set includes outputting a main refocusing pulse sequence and at least one subsequent refocusing pulse sequence into a zone of interest, outputting a randomizing pulse from a randomizing pulse module into the zone of interest to remove a net detected residual magnetization, and sensing the NMR data set from the zone of interest.