Multi-Attribute Acoustic Characterization of Multiple Casing Strings
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Solution Overview
Problem
Existing cement evaluation tools in the oil and gas industry are limited in their ability to assess cement bonds between multiple casing strings, typically relying on single attributes of acoustic waveforms and failing to characterize the second and third interfaces effectively, which is crucial for ensuring well integrity and preventing fluid flow paths.
Innovation Solution
A method and system that utilize multiple waveform attributes from the acoustic spectrum, including amplitude, frequency, and phase variations, to evaluate and characterize cement bonds between multiple casing strings, allowing for a more direct and accurate assessment of cement bond quality by analyzing the different densities at casing-cement interfaces and annular regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing cement evaluation tools use only one system of sonic/ultrasonic sensors and analyze only one attribute of the acoustic waveform (such as amplitude), then the device complexity is reduced and ease of operation is improved, but the measurement precision and reliability of cement bond characterization are insufficient, particularly for multiple casing strings
Solution Approach 1:
The patent divides the cement evaluation process into multiple independent analysis dimensions by using multiple sensor systems (active acoustic, passive acoustic, ultrasonic) and analyzing multiple waveform attributes (amplitude, frequency, phase, wavelet transforms) separately, then integrating their results to achieve comprehensive cement bond characterization across multiple casing strings
Solution Approach 2:
The evaluation system is designed to perform multiple functions using a unified framework: it can evaluate cement bonds at multiple interfaces (casing-cement, cement-formation), characterize materials in annular spaces, detect fluid flow paths, and assess cement quality across different wellbore configurations, all through the integrated multi-attribute analysis platform
2Reliability
If existing tools are limited to characterization of the first casing-cement bond only, then the device complexity and data processing requirements are reduced, but the reliability of overall well integrity assessment is compromised due to inability to evaluate second and third interfaces
Solution Approach 1:
The patent extends the evaluation from a single interface (first casing-cement bond) to multiple interfaces (first, second, and third interfaces) by adding spatial dimensions to the analysis. The system uses multiple sensor systems operating in different physical dimensions (active acoustic waves, passive acoustic signals, ultrasonic waves) to characterize cement bonds at each interface simultaneously
Solution Approach 2:
The patent introduces material density as an intermediary parameter that mediates the relationship between acoustic wave propagation and cement bond quality. By analyzing how acoustic waves interact with materials of different densities at each interface, the system can reliably characterize cement bonds across multiple casing strings without requiring direct physical contact with each interface
3Measurement precision
If multiple waveform attributes (amplitude, frequency, phase) are analyzed to improve cement bond assessment accuracy, then measurement precision is improved, but the data processing complexity and time requirements increase
Solution Approach 1:
The patent applies wavelet transforms and other signal processing techniques to decompose the acoustic waveforms into their constituent frequency and phase components before analysis. This preliminary decomposition allows for more efficient processing of multiple waveform attributes by organizing the data into meaningful frequency bands and temporal patterns, reducing the overall processing time
Solution Approach 2:
The patent replaces traditional time-domain analysis methods with frequency-domain and time-frequency domain analysis methods (Fourier transforms, wavelet transforms). This substitution allows for parallel processing of multiple waveform attributes and enables more efficient extraction of cement bond characteristics from the acoustic signals
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 more accurate and comprehensive cement bond quality assessments, improving well integrity by identifying potential fluid flow paths and ensuring effective zonal isolation in complex wellbore configurations, including vertical, horizontal, and nonlinear wellbores.
Implementation Method 1
transmitting acoustic waves into the formation and recording acoustic waves returning from the formation
Implementation Method 2
wave reflection and refraction occur at interfaces that correspond to changes in the acoustic impedance of the medium
Implementation Method 3
wave reflection and refraction occur at interfaces that correspond to changes in the acoustic impedance of the medium
Implementation Method 4
extracting one or more acoustic attributes, including instantaneous acoustic attributes, from the acoustic data
Data Source
AI summary
Methods, systems, and computer program products for characterizing materials in a wellbore having multiple casing strings uses well completion data and instantaneous frequency, instantaneous phase, and/or amplitude attributes, including waveform amplitude or instantaneous amplitude, of an acoustic waveform to determine material densities, acoustic velocities and acoustic travel distances for the materials between the various stages of casings.