Rotatable Collimator Sleeve for Azimuthal Gamma Ray Logging
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Solution Overview
Problem
Traditional downhole logging tools lack azimuthal resolution due to fixed collimation of the radiation source and detector, requiring multiple runs to evaluate different formation areas, which is time-consuming and costly.
Innovation Solution
A downhole logging tool with a rotatable sleeve around the radiation source, allowing for adjustable apertures to inspect different regions of the formation, combined with compressive sensing techniques to reconstruct azimuthal information from reduced acquisition data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the source and detector are fixed collimated, then the instrument structure is simple, but azimuthal resolution is lost and multiple runs are required
Solution Approach 1:
The patent applies dynamics by making the collimator sleeve rotatable around the radiation source, transforming the fixed collimation system into a dynamic one. The sleeve can be rotated to different angular positions to direct gamma rays at various azimuthal angles, enabling the instrument to inspect different regions of the formation without requiring multiple separate runs. This dynamic adjustment resolves the contradiction by providing azimuthal resolution while maintaining a relatively simple instrument structure.
Solution Approach 2:
The collimator is segmented into a modular sleeve structure that can be independently rotated. This segmentation allows the collimation function to be separated from the main instrument body, enabling flexible angular positioning. The sleeve acts as an independent component that can be adjusted to different orientations, providing azimuthal coverage without complicating the overall instrument design.
2Measurement precision
If the source and detector are rotated to inspect different regions, then azimuthal resolution is achieved, but acquisition time increases
Solution Approach 1:
The patent applies partial action by using a limited number of discrete angular positions for the collimator sleeve rather than continuous rotation. The sleeve can be positioned at specific predetermined angles (e.g., 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°), which provides sufficient azimuthal coverage for most logging applications. This partial sampling approach reduces acquisition time compared to continuous rotation while still achieving meaningful azimuthal resolution.
Solution Approach 2:
The patent changes the operational parameter from continuous angular rotation to discrete angular positioning. By defining specific angular positions for the collimator sleeve, the system achieves azimuthal resolution with fewer measurement steps. This parameter change from continuous to discrete operation significantly reduces the time required to acquire azimuthal data while maintaining measurement precision.
3Adaptability or versatility
If multiple runs are performed to evaluate different formation areas, then complete formation inspection is achieved, but operational cost increases
Solution Approach 1:
The patent applies universality by designing a single instrument that can perform multiple inspection functions by rotating the collimator sleeve to different angular positions. The same gamma ray source and detector assembly can inspect formation properties at various azimuthal angles without requiring separate instruments or multiple logging runs. This multi-functionality reduces operational costs by consolidating what would otherwise require multiple separate operations into a single versatile tool.
Solution Approach 2:
The dynamic rotatable collimator sleeve enables a single instrument to adapt to different inspection requirements by changing its angular orientation. This dynamic capability allows the instrument to cover the entire azimuthal range of the formation in one logging run, eliminating the need for multiple runs and reducing operational costs while maintaining comprehensive formation inspection coverage.
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
Enhances azimuthal resolution and reduces acquisition time by allowing for efficient data collection and reconstruction of formation characteristics with fewer measurements, thereby decreasing operational costs.
Implementation Method 1
Some gamma ray instruments send gamma rays into a formation and detect those that are scattered back
Implementation Method 2
The tool also includes a sleeve positioned around the radiation generation source, the sleeve including at least one aperture for forming a pathway for a radiation beam
Data Source
AI summary
A downhole logging tool includes a radiation generation source operable to emit radiation into a formation surrounding the tool and a radiation detector operable to detect backscattered radiation from the formation surrounding the tool. The tool also includes a sleeve positioned around the radiation generation source, the sleeve including at least one aperture for forming a pathway for a radiation beam, emitted from the radiation generation source, to enter the formation, the sleeve being rotatable about an axis of the tool to change a position of the aperture to distinctly inspect different regions of the formation.