Well Casing Thickness Measurement via Acoustic Wave Correlation
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Solution Overview
Problem
Conventional technologies for measuring well casing thickness are inaccurate for casings thicker than 1 inch, particularly in oil fields with active tectonic movements, as they rely on low-frequency acoustic waves that are limited by casing diameter, affecting the reliability of cement bonding evaluations crucial for oil field safety and economy.
Innovation Solution
The method involves using a correlation between measured and model waveforms to estimate casing thickness, independent of cement and fluid impedance, by comparing waveforms recorded with a transducer configuration that accounts for casing curvature and radiation patterns, allowing for accurate measurements of casings thicker than 1 inch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If low-frequency acoustic waves are used for casing thickness measurement, then the measurement can be performed on casings of various diameters, but the measurement accuracy deteriorates for casings thicker than 1 inch
Solution Approach 1:
The patent changes the fundamental measurement parameter from low-frequency acoustic wave travel time to high-frequency acoustic wave reverberation spectral analysis. By using high-frequency waves (above 100 kHz) and analyzing the spectral characteristics of reverberations within the casing wall, the system achieves accurate thickness measurements for casings thicker than 1 inch while maintaining adaptability to various casing diameters.
Solution Approach 2:
The patent utilizes mechanical vibration principles by analyzing the reverberation frequencies of acoustic waves bouncing within the casing wall. The reverberation spectrum contains frequency peaks that are directly related to the casing thickness, allowing precise measurement through spectral analysis rather than simple travel time measurement.
2Ease of operation
If conventional acoustic wave methods are used, then the measurement process is simple, but the reliability of cement bonding evaluation deteriorates in areas with active tectonic movements
Solution Approach 1:
The patent replaces the conventional mechanical/acoustic travel time measurement system with a high-frequency spectral analysis system. By substituting simple time-of-flight measurement with sophisticated spectral analysis of reverberations, the system achieves reliable cement bonding evaluation even in challenging tectonic conditions while maintaining operational simplicity through automated analysis.
Solution Approach 2:
The patent introduces spectral analysis as an intermediary process between acoustic wave transmission and thickness determination. The reverberation spectrum serves as an intermediate representation that contains encoded information about casing thickness and cement bonding quality, allowing reliable evaluation through pattern recognition in the spectral domain.
3Device complexity
If low-frequency acoustic waves are used, then the equipment requirements are minimal, but the accuracy of thickness measurement for thick casings deteriorates
Solution Approach 1:
The patent employs high-frequency mechanical vibration (acoustic waves above 100 kHz) that resonate within the casing wall structure. By analyzing the vibration spectral characteristics and reverberation patterns, the system achieves precise thickness measurements for thick casings without requiring complex additional equipment beyond a capable acoustic transmitter and receiver.
Solution Approach 2:
The patent accounts for the curved geometry of the casing by analyzing reverberations that propagate along the curved wall surface. The spectral analysis method naturally accommodates the cylindrical geometry, extracting thickness information from the reverberation patterns that are influenced by the casing curvature without requiring complex geometric corrections.
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 enhances the accuracy of well casing thickness measurements and cement bonding evaluations, ensuring the safety and economic efficiency of oil field operations by reducing reliance on low-frequency waves and improving data correlation analysis.
Implementation Method 1
an acoustic transmitter and an acoustic receiver are operated within a wellbore that includes a well casing
Implementation Method 2
a measured waveform associated with an acoustic signal returned via the well casing
Data Source
AI summary
Systems, methods, and software for determining a thickness of a well casing are described. In some aspects, the thickness of the well casing is determined based on results of comparing a measured waveform and model waveforms. The measured waveform and model waveforms are generated based on operating an acoustic transmitter and an acoustic receiver within a wellbore comprising the well casing.