Replaceable Thermal Neutron Absorbing Sleeve for Detector Saturation
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Solution Overview
Problem
Pulsed neutron logging tools experience unwanted noise and reduced effectiveness due to thermal neutron radiation, which saturates detectors and interferes with the measurement of gamma rays and thermal neutrons.
Innovation Solution
Incorporating a thermal neutron absorption layer between the gamma ray detector and thermal neutron radiation to absorb neutrons, reducing interference and enhancing the tool's effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pulsed neutron generator is used to transmit neutrons into a formation for measurements, then the ability to detect gamma rays and thermal neutrons is improved, but thermal neutron radiation saturates detectors and creates unwanted noise that reduces measurement accuracy
Solution Approach 1:
A thermal neutron absorbing sleeve is introduced as an intermediary component between the pulsed neutron generator and the detectors. This sleeve absorbs thermal neutron radiation before it reaches the detectors, preventing saturation and reducing unwanted noise, thereby resolving the contradiction between enabling neutron transmission for measurement and preventing thermal neutron interference with detector accuracy
2Measurement precision
If thermal neutron absorption material is added to reduce thermal neutron radiation, then detector saturation is reduced and measurement accuracy is improved, but the device complexity increases
Solution Approach 1:
The thermal neutron absorbing sleeve is designed as a thin tubular component that can be easily integrated into the existing pulsed neutron tool structure. This thin-film approach provides effective thermal neutron absorption while minimizing the increase in device complexity and maintaining a compact tool design
3Object-affected harmful factors
If a thermal neutron absorbing sleeve is added between the neutron generator and detectors, then thermal neutron interference is reduced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The pulsed neutron tool is segmented into distinct functional components: the neutron generator, the thermal neutron absorbing sleeve, and the detectors. This segmentation allows the absorbing sleeve to be manufactured separately using standard techniques and then assembled into the tool, simplifying the overall manufacturing process while effectively addressing thermal neutron interference
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 thermal neutron absorption layer improves the accuracy and efficiency of pulsed neutron logging tools by minimizing detector saturation and enhancing the measurement of both gamma rays and thermal neutrons.
Implementation Method 1
a thermal neutron absorption layer configured to absorb neutrons from thermal neutron radiation
Data Source
AI summary
A downhole system may include a downhole tubular having a body portion formed between a central bore and a radially outer surface of the downhole tubular, a neutron generator housed within the body portion and configured to emit neutrons, and a gamma ray detector housed within the body portion and configured to detect gamma rays formed via interactions between the emitted neutrons and a downhole formation. The downhole system may also include a sleeve disposed about the radially outer surface of the downhole tubular. The sleeve may be axially positioned over at least a portion of the gamma ray detector. Additionally, the downhole system may include a thermal neutron absorption layer disposed between a radially outer surface of the sleeve and the gamma ray detector.