Acoustic Cement Bond Evaluation Using Waveform Attenuation
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Solution Overview
Problem
Current methods for evaluating cement bonding to well casing in hydrocarbon wells are insufficient, leading to potential fluid leakage and safety issues due to inadequate assessment of cement integrity.
Innovation Solution
A methodology and system that collect and process waveform data to derive amplitude-based and attenuation-based bond indices, using models to prepare quality control plots, enabling reliable cement bonding evaluation through downhole tools and systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional cement bonding evaluation methods are used, then the evaluation process is simple, but the measurement precision and reliability of cement bonding assessment are insufficient
Solution Approach 1:
The patent replaces traditional mechanical/cement-based bonding assessment with acoustic wave-based evaluation. Downhole tools emit acoustic waves that propagate through the cement sheath, and receivers detect wave characteristics (amplitude, frequency, travel time) to quantitatively assess bonding quality between casing and formation, achieving precise measurement without complex mechanical intervention.
Solution Approach 2:
The patent utilizes changes in acoustic wave parameters (amplitude attenuation, frequency spectrum, travel time) as the cement bonding quality changes. By monitoring these parameter variations, the system quantitatively evaluates bonding strength, transforming a qualitative assessment into a precise parameter-based measurement system.
2Reliability
If downhole tools are used for cement bonding evaluation, then the reliability of wellsite operations is improved, but the device complexity increases
Solution Approach 1:
The downhole tools are designed with multi-functionality, serving both as drilling/Logging tools and as acoustic emission/reception systems. The same tool string that performs primary well functions also contains acoustic sources and receivers for cement bonding evaluation, eliminating the need for separate dedicated bonding assessment equipment and reducing overall system complexity.
Solution Approach 2:
The evaluation system utilizes the wellbore environment itself (casing, cement sheath, formation) as the test medium. The acoustic waves naturally propagate through these structures, and their interaction with the bonding interface provides self-diagnostic information about bonding quality, eliminating the need for external testing apparatus.
3Loss of information
If quantitative bond index logs are generated, then the loss of information is reduced, but the processing time and device complexity increase
Solution Approach 1:
The system performs preliminary processing of acoustic wave data during the logging operation itself. Bond indices are calculated in real-time or near-real-time as the tools traverse the wellbore, and quality control plots are generated concurrently with data acquisition. This preliminary action prevents information loss and eliminates the need for extensive post-processing, reducing overall time loss.
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
Facilitates accurate cement bonding evaluation across a wide range of logging conditions, ensuring reliable wellsite operations by providing quantitative bond index logs and quality control measures, effectively preventing fluid leakage and ensuring safe operations.
Implementation Method 1
a downhole tool is lowered into the well on a logging operation. The downhole tool includes a source that emits an acoustic wave
Implementation Method 2
The technique also may include calculation of waveform amplitude, waveform attenuation
Data Source
AI summary
A technique facilitates cement bonding evaluation including collecting waveform data and pre-processing the waveform data. The technique also may utilize processes which provide a time window position for the pre-processed waveform data and calculation of waveform amplitude and/or attenuation. Additionally, the technique may include deriving an amplitude-based bond index and/or attenuation-based bond index through the use of a model or other suitable waveform data processing technique which enables preparation of quality control plots with respect to the processing results.