Movable Gamma Ray Source Shielding for Downhole Logging
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Solution Overview
Problem
Downhole gamma ray inspection tools face challenges in shielding the gamma ray source, leading to health, safety, and environmental concerns due to excessive radiation exposure, particularly near openings associated with the collimator, which delays operations and requires personnel to be at a distance.
Innovation Solution
A downhole logging system with a gamma ray source and collimator that includes a movable source package with shielding material, allowing the source to be aligned with the collimator only when in use, reducing radiation exposure by using a linear actuator to transition the source between shielded and un-shielded positions, and a clamp-on shield with uniform thickness to manage radiation levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gamma ray source is positioned near the collimator opening for effective radiation direction, then the gamma ray scanning capability is improved, but radiation exposure to personnel increases creating safety hazards
Solution Approach 1:
The source is made movable relative to the collimator opening through a deployment mechanism. The source can be positioned near the opening for scanning operations and retracted to a shielded position when not in use, dynamically adjusting the radiation exposure level based on operational requirements
Solution Approach 2:
The gamma ray source is extracted from a permanently fixed position and placed on a movable platform or carriage that can be deployed to the collimator opening only when needed. This separates the source from the fixed tool structure, allowing controlled exposure during operations while maintaining shielding during transport and storage
2Object-affected harmful factors
If the source is permanently shielded during transport and storage, then radiation safety is improved, but the time required to deploy and prepare the source for scanning operations increases
Solution Approach 1:
The source is pre-positioned in a shielded container or recess that provides automatic shielding upon insertion into the tool. The deployment mechanism is pre-configured so that when the source is inserted, it automatically engages with the deployment system, reducing the time required to prepare for scanning operations
Solution Approach 2:
A rapid deployment mechanism is implemented that can quickly transition the source from the shielded transport position to the operational position near the collimator opening. This dynamic system minimizes the time the source is in transit while maintaining safety during storage and transport
3Object-affected harmful factors
If heavy shielding material is used to protect personnel from radiation, then radiation exposure is reduced, but the weight of the logging tool increases
Solution Approach 1:
Instead of providing continuous heavy shielding, the system uses dynamic positioning to bring the source close to the collimator opening only when scanning is required. This eliminates the need for heavy permanent shielding, reducing overall tool weight while maintaining radiation safety during transport and storage through the deployment mechanism
Solution Approach 2:
Shielding is applied locally at critical positions such as the source container and retraction position, rather than providing uniform shielding throughout the tool. This localized approach reduces overall weight while maintaining adequate protection during non-operational phases
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 system effectively reduces radiation exposure to within safe limits, allowing for safer operations and reducing the dose field around the tool, enabling more efficient and secure downhole inspections.
Implementation Method 1
a gamma ray source positioned within a logging tool, the gamma ray source to emit radiation into an area surrounding the logging tool
Implementation Method 2
detect backscatter radiation from the area
Implementation Method 3
a collimator associated with the gamma ray source, the collimator to adjust an opening to direct a flow of radiation into the formation
Implementation Method 4
The source receptacle includes a first shielding material, the first shielding material being movable from a first position blocking the aperture
Implementation Method 5
reducing radiation exposure by using a linear actuator to transition the source between shielded and un-shielded positions
Data Source
AI summary
A downhole logging system includes a gamma ray source positioned within a logging tool. The system further includes a collimator associated with the gamma ray source, the collimator having an opening to direct a flow of radiation into the formation. The system also includes a radiation detector operable to detect backscatter radiation from the area. The system further includes a motor to rotate the collimator in either a continuous or stepping fashion for scanning a borehole and an actuator associated with the gamma ray source. The actuator moves the gamma ray source between a first position and a second position, the first position being misaligned with the opening and the second position being aligned with the opening.