Fiber Scintillator Borehole Logging Gamma Interference
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Solution Overview
Problem
Conventional borehole logging methods face challenges in accurately estimating parameters such as density and porosity due to interference from gamma rays originating from outside the volume of interest, such as the borehole.
Innovation Solution
The use of a formation evaluation tool featuring a coherent assemblage of joined fibers, which are sensitive to gamma rays and neutrons, surrounded by a further scintillation media with different characteristics. This configuration includes photodetectors to differentiate between light scintillations from the fibers and the additional scintillation media, allowing for enhanced detection and estimation of formation parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional scintillation detectors are used in borehole logging, then gamma rays from outside the volume of interest (such as from the borehole) can be detected, but the accuracy of parameter estimation deteriorates due to interference from these non-target gamma rays
Solution Approach 1:
The scintillation detector is segmented into multiple scintillation media with different characteristics (e.g., different densities, atomic numbers, or light emission properties). Each medium responds differently to gamma rays from various directions or energies, allowing the system to distinguish between formation gamma rays and borehole gamma rays through comparative analysis of signals from different segments.
Solution Approach 2:
Different regions of the scintillation detector are assigned different local qualities or properties. For example, the detector may have varying scintillation material compositions, densities, or geometric arrangements in different zones, enabling each region to be optimized for detecting specific types of radiation while rejecting others, thereby improving the ability to discriminate against harmful gamma ray interference.
2Measurement precision
If a coherent assemblage of joined fibers with different scintillation characteristics is used, then light collection and energy resolution are improved, but the device complexity increases
Solution Approach 1:
The detector employs a nested structure where multiple scintillation media are arranged concentrically or in layered configurations around a central axis. This nesting allows different scintillation materials to be integrated in a compact, organized manner, improving light collection efficiency and energy resolution while managing the inherent complexity through systematic spatial arrangement rather than random or dispersed configurations.
Solution Approach 2:
The detector uses composite scintillation media comprising multiple materials with complementary properties. By combining materials with different densities, atomic numbers, and light emission characteristics, the system achieves superior energy resolution and detection capability. The composite structure allows each material to contribute its strengths, creating a synergistic effect that improves measurement precision while the integrated design manages structural complexity.
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 improves the accuracy of parameter estimation by minimizing interference from non-target gamma rays and enhancing light collection and energy resolution, leading to more precise geological and petrophysical data.
Implementation Method 1
The scintillation media is sensitive to at least one of neutrons and gamma ray radiation
Implementation Method 2
Optical detector units are optically coupled to at least one end of each elongated scintillator member so as to detect optical signals from each elongated scintillator member
Data Source
Figure 1~2B
Figure 3~4
Figure 5A~6
AI summary
One general embodiment according to the present disclosure may be formation evaluation tool for detecting radiation in a borehole in a volume of an earth formation. The tool may include a detector including a monolithic scintillation element comprising a coherent assemblage of joined fibers, wherein the fibers are made of an optically transparent scintillation media. The fibers may be at least one of i) gamma ray responsive; and ii) neutron responsive. The coherent assemblage of fibers may be a continuous mass, may be heat-joined. The fibers may be solid. The scintillation media may comprise at least one of i) organic crystalline scintillation materials, ii) amorphous glass, and iii) nanostructured glass ceramics. The coherent assemblage of fibers may be asymmetric. The coherent assemblage of fibers may surround a further scintillation media having different scintillation characteristics than the scintillation media. The scintillation element may be azimuthally sensitive.