Eddy Current Pipe Thickness Restoration via Deconvolution
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Solution Overview
Problem
Existing electromagnetic induction tools for downhole corrosion detection in well casings face challenges in accurately locating corrosion defects due to the 'ghost effect,' which causes double peak responses, making it difficult to determine the true location and magnitude of defects, especially in multiple pipe scenarios.
Innovation Solution
A true thickness restoration algorithm is implemented to reduce the ghost effect by using 1D and Fourier transform-based methods to deconvolve and adjust the thickness estimation results, providing accurate and independent vertical resolution for defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate transmitter and receiver coils are placed at different positions along the depth, then better characterization of outer pipes is achieved, but double peak effect occurs making true defect location difficult to ascertain
Solution Approach 1:
The patent applies preliminary action by performing deconvolution processing on the measured response data before defect location identification. The system pre-processes the double peak response data using deconvolution algorithms to separate the transmitter and receiver peak effects, thereby recovering the true defect location information before final analysis. This preliminary processing step eliminates the information loss that would otherwise occur during standard interpretation.
2Measurement precision
If larger transmitter-receiver distances are used, then better characterization of outer pipes is achieved, but double peak effect becomes more pronounced
Solution Approach 1:
The patent introduces an intermediary processing step (deconvolution algorithm) between the measurement process and defect interpretation. This intermediary computational method acts as a mediator that separates the overlapping transmitter and receiver peak effects in the measured response, allowing the system to maintain large transmitter-receiver distances for outer pipe characterization while still accurately determining defect locations through mathematical separation of the double peak signal.
3Device complexity
If standard inversion algorithms are used on double peak responses, then processing is simplified, but thickness estimation errors increase
Solution Approach 1:
The patent applies preliminary deconvolution processing to the measured response data before applying standard inversion algorithms. By pre-separating the double peak effects through deconvolution, the system enables the use of simpler standard inversion methods while achieving accurate thickness estimates. The preliminary processing step transforms the complex double peak response into a form that can be accurately interpreted using conventional inversion techniques, thereby maintaining low processing complexity while eliminating thickness estimation errors.
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 algorithm effectively reduces errors in thickness estimation, accurately identifying defects at their true depth and magnitude, enhancing the accuracy of pipe characterization and enabling more precise inspection of outer pipes.
Implementation Method 1
The transmitter generates a primary field that induces eddy currents inside the metallic pipes
Implementation Method 2
the receiver records secondary fields generated from the pipes. Those secondary fields bear information about the electrical properties and metal content of the pipes
Data Source
AI summary
Apparatus and methods to investigate a multiple nested conductive pipe structure can be implemented in a variety of applications. An electromagnetic pulsed tool disposed in the multiple nested conductive pipe structure in a wellbore can make a set of log measurements and provide a measured log at different depths in the multiple nested conductive pipe structure. A test setup or library can provide a set of small defect log measurements. Processing circuitry can process the set of log measurements to generate thickness estimations of the multiple nested conductive pipes and processing circuitry can process the set of small defect log measurements to generate small defect thickness estimations. Processing circuitry can solve a system of equations involving the thickness estimations and the small defect thickness estimations to generate thickness variations for the multiple nested conducted pipes over the different depths. Additional apparatus, systems, and methods are disclosed.