Saddle Coil EM Inspection for Quadrant Casing Defect Localization
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Solution Overview
Problem
Conventional electromagnetic (EM) field testing tools miss localized defects in well casings due to their circumferentially averaged sensitivity, failing to detect asymmetrical corrosion or metal loss that can compromise well integrity.
Innovation Solution
An EM inspection tool with a triaxial transmitter and triaxial receivers, configured to operate at multiple frequencies and spacings, provides quadrant-based localization of defects by analyzing multi-frequency, non-collocated induction measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional EM field testing tools are used, then the measurement process is simple, but the measurement precision is insufficient to detect localized defects
Solution Approach 1:
The EM inspection tool is divided into multiple triaxial receiver pairs, each sensitive to different spatial quadrants of the casing. This segmentation allows the system to detect localized defects in specific quadrants while maintaining overall system functionality, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent transitions from conventional single-axis or bipolar measurement configurations to a triaxial measurement system that operates in three-dimensional space. By adding spatial dimensions (radial, tangential, and axial directions), the system achieves superior defect localization capability without proportionally increasing complexity.
2Reliability
If conventional EM field testing is performed, then the inspection process is straightforward, but the ability to detect asymmetrical corrosion is insufficient
Solution Approach 1:
The patent employs an asymmetric measurement configuration with triaxial receiver pairs positioned at different spacings from the transmitter. This asymmetric arrangement creates distinct sensitivity patterns for defects in different quadrants, enabling reliable detection of asymmetrical corrosion that would be invisible to symmetric conventional tools.
Solution Approach 2:
The triaxial receiver pairs act as intermediaries that translate complex electromagnetic field interactions with localized defects into measurable signals. By positioning receivers at multiple spacings and orientations, the system mediates between the electromagnetic field and the detection system, making localized defects detectable despite the inherent difficulty of the measurement task.
3Measurement precision
If multi-frequency, non-collocated induction measurements are obtained, then defect localization accuracy is improved, but the data processing complexity increases
Solution Approach 1:
The system employs multi-frequency electromagnetic excitation, applying periodic signals at different frequencies to the casing. This periodic action at multiple frequencies creates distinct response patterns that encode spatial information about defects, enabling accurate quadrant localization while managing data processing complexity through frequency-domain analysis.
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
Enables early detection and precise localization of defects in well casings, ensuring well integrity by identifying metal loss or gain in specific quadrants of the casing.
Implementation Method 1
The triaxial transmitter is configured to emit a respective one or more primary time-varying magnetic field signals in the plurality of casings... each of the respective one or more primary time-varying magnetic field signals induces a corresponding one or more secondary time-varying magnetic field signals in the plurality of casings
Implementation Method 2
the one or more secondary time-varying magnetic field signals are detected by one or more of the plurality of triaxial receivers. The method also includes obtaining, using the EM inspection tool, induction measurements of the plurality of casings
Data Source
AI summary
Techniques and apparatus for determining quadrant-based locations of casing defects based on multi-frequency, non-collocated, induction measurements are described. An electromagnetic (EM) inspection tool is operated inside of a well including multiple casings. The EM inspection tool includes a triaxial transmitter and multiple triaxial receivers, each being located at a different spacing from the triaxial transmitter. The triaxial transmitter is configured to emit primary time-varying magnetic field signals in a radial direction, a tangential direction, and an axial direction. Each respective primary time-varying magnetic field signal induces corresponding secondary time-varying magnetic field signal(s) in the radial direction, the tangential direction, and the axial direction that are detected by one or more of the triaxial receivers. Induction measurements of the casings are obtained using the EM inspection tool, and a quadrant of a casing in which a defect of the casing is located is determined based on the induction measurements.