ICA Decomposition of Acoustic Waveforms for Cement Bonding Assessment
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Solution Overview
Problem
Current methods for evaluating cement-bonding quality in plugged and abandoned wells face challenges in accurately interpreting sonic logs and reliably identifying cement bonding losses due to mixed signals from casing, formation, cement, and borehole fluid, which are not effectively separated by existing filtering techniques.
Innovation Solution
The system employs independent component analysis (ICA) to process variable density log (VDL) data in the time domain, decomposing waveforms into multiple components associated with local structure variances of the well structure, allowing for the determination of independent components and subsequent transformation into the frequency domain for further analysis and confirmation of patterns and features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If acoustic measurements are processed using conventional filtering techniques, then the processing time is reduced, but the measurement precision deteriorates because mixed signals from casing, formation, cement, and borehole fluid are not effectively separated
Solution Approach 1:
The patent applies Independent Component Analysis (ICA) to decompose the mixed acoustic signal into multiple independent components, each representing different physical sources (casing waves, formation waves, cement bonding conditions, borehole fluid effects). This segmentation separates the previously mixed signals into distinct components that can be individually analyzed, thereby improving measurement precision without requiring extensive manual processing time
Solution Approach 2:
The patent introduces an intermediary processing layer that transforms the raw mixed acoustic signal into a set of independent components through ICA. This intermediary representation serves as a bridge between the raw data and the final interpretation, allowing for more accurate identification of cement bonding conditions by isolating the relevant signal components from interfering sources
2Adaptability or versatility
If the acoustic signal is transmitted through tubing to evaluate cement bonding, then the ability to assess plugged and abandoned wells is improved, but the signal quality deteriorates due to high impedance contrasting the tubing and fluid that confines the energy
Solution Approach 1:
The patent extracts the useful signal components from the confined acoustic energy within the tubing by applying ICA to separate the independent components representing different physical phenomena. This extraction process isolates the cement bonding information from the tubing-confined energy, enabling accurate evaluation despite the impedance contrast and energy confinement
Solution Approach 2:
The patent transforms the acoustic signal from the time domain to the frequency domain and applies ICA to change the parameter representation of the signal. This parameter transformation allows for better separation of the mixed signals and improved identification of cement bonding conditions, overcoming the limitations imposed by tubing confinement
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
This approach enables reliable evaluation of cement-bonding quality by accurately identifying local structure variances and confirming patterns and features, effectively distinguishing between different well structure conditions such as free pipe, casing collar, and cement bonding conditions, improving the accuracy of well integrity assessment.
Implementation Method 1
transmitting an acoustic signal from a well inspection tool into a well structure
Implementation Method 2
One or more return signals is detected, as part of the method, using at least one receiver of the well inspection tool
Data Source
AI summary
A method and system to be used in well inspection. An acoustic signal is transmitted from a well inspection tool into a well structure and one or more return signals is detected using at least one receiver. At least one processor is used to generate variable density log (VDL) data that includes multiple waveforms in a time domain from the one or more return signals. A number of independent components to be used based on variances in the VDL data is determined and the multiple waveforms are decomposed into multiple components associated with one or more local structure variances of the well structure using independent component analysis (ICA) and the number of independent components. Characteristics of the well structure is determined based in part on patterns or features associated with one or more independent components from the multiple components.