Multi-Sized Gamma Windows for Cement and Casing Flaw Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gamma ray scanners for cement and casing flaw detection in multistring completions suffer from sinusoidal background interference due to off-centered rotation, leading to low count rates and difficulty in visual representation of flaws, which conventional image processing methods fail to adequately address.
Innovation Solution
A gamma ray scanner with multi-sized windows, diametrically opposite to each other, receives gamma rays simultaneously to determine first and second gamma counts at different alignments, suppressing background contrast using a gamma contrast range derived from these counts to generate a clear visual representation of flaws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the tool is rotated with an off-centered rotation axis to adapt to completed wellbores, then the tool can be positioned away from the center of the wellbore, but a sinusoidal background is generated in the scan which degrades visual representation and makes flaw detection difficult
Solution Approach 1:
The patent applies asymmetry by using two windows of different sizes (first window larger than second window) positioned diametrically opposite each other. This asymmetric configuration allows the tool to compensate for off-centered rotation effects. The larger window captures more gamma rays when positioned away from the wellbore center, while the smaller window captures fewer gamma rays when positioned closer to the center, creating an asymmetric response that counteracts the sinusoidal background interference and maintains measurement precision.
Solution Approach 2:
The patent changes the geometric parameter of the detection windows by using two windows of different sizes rather than identical windows. This parameter change (window size differentiation) transforms the detection system's response characteristics, enabling it to differentiate between signal variations caused by cement/casing flaws and those caused by off-centered rotation, thereby resolving the contradiction between positioning flexibility and measurement precision.
2Measurement precision
If post-processing methods are used to mitigate sinusoidal background influence, then the visual representation can be improved, but additional processing steps and complexity are introduced
Solution Approach 1:
The patent implements preliminary action by designing the window configuration and data acquisition process to inherently compensate for off-centered rotation effects before visual representation is generated. The asymmetric window sizes and the specific method of acquiring and comparing gamma ray counts from windows of different sizes pre-process the data to minimize sinusoidal background interference, eliminating or reducing the need for additional post-processing steps.
Solution Approach 2:
The detection system performs self-service by using its own asymmetric window configuration to automatically compensate for off-centered rotation. The system's inherent design (different sized windows) provides the correction mechanism, eliminating the need for external post-processing methods and reducing overall system complexity while maintaining measurement precision.
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 suppresses sinusoidal background interference, enhancing the clarity of flaw detection in cement and casing by adjusting contrast in specific areas, allowing for accurate flaw identification even with off-centered rotation.
Implementation Method 1
a single scintillating crystal to receive gamma rays returned from a formation and a wellbore
Data Source
AI summary
A detector to determine flaws in cement and casing associated with a formation using a visual representation of gamma rays received simultaneously through at least two windows that are of different sizes and that are diametrically opposite to each other in a rotating shield including a single scintillating crystal, where the visual representation is to indicate the flaws and includes a background with at least part of a contrast that is suppressed based in part on a gamma contrast range obtained from at least first gamma counts from gamma rays received at a first degree of alignment of the two windows with respect to an azimuth that is associated with the formation and second gamma counts from the gamma rays received at a second degree of alignment of the two windows that is offset from the first degree of alignment.