Real-time Cement Bond Logging via Correlation Noise Filtering
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Solution Overview
Problem
The challenge in cementing oil or gas wells is accurately measuring the quality of cement bonding between the wellbore casing and the Earth formation during the cementing process, as background noise from cementing tools interferes with acoustic measurements, leading to biased estimates of cement bond indices and attenuation values.
Innovation Solution
The method involves transmitting and receiving acoustic signals, filtering the data, identifying magnitude and attenuation values, and applying correction rules based on correlation coefficients to accurately determine bond indexes in real-time, even in noisy environments, using a computer model to refine the attenuation values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic logging is performed during cementing operations, then real-time cement bond quality can be measured, but tool noise and background interference bias the measurement results
Solution Approach 1:
The patent converts the harmful tool noise and background interference into useful information by calculating correlation coefficients between the noisy acoustic signals and expected cement bond signatures. The correlation analysis allows the system to distinguish between signals caused by actual cement bonding and those caused by tool noise, effectively transforming the interference into a diagnostic parameter for measurement quality assessment.
Solution Approach 2:
The patent introduces correlation coefficients as an intermediary parameter that mediates between the noisy acoustic measurements and the true cement bond conditions. By computing correlation coefficients between the acoustic signals and reference profiles, the system creates a intermediate representation that filters out noise while preserving the essential bonding information, enabling accurate measurement despite the presence of tool noise.
2Measurement precision
If correction rules based on correlation coefficients are applied, then measurement accuracy improves, but processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing correlation coefficient thresholds and correction rules before the actual measurement process. The system uses pre-computed reference acoustic profiles and predetermined correlation thresholds to guide real-time corrections, avoiding the need for complex real-time calculations while maintaining high measurement accuracy through rule-based processing.
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 precise, real-time assessment of cement bonding quality, reducing the impact of tool noise and improving the accuracy of cement bond log generation, thereby enhancing well integrity and reducing costs.
Implementation Method 1
an acoustic transmitter and one or more acoustic receivers are used to collect data relating to the quality of a wellbore annulus cementing operation
Implementation Method 2
receiving acoustic signals, filtering the received acoustic signals, identifying magnitude and attenuation values
Data Source
AI summary
Aspects of the subject technology relate to systems and methods for identifying the quality of cement bonding of an exterior surface of a wellbore casing to an Earth formation. Methods of the present disclosure may allow for bond indexes to be identified in real-time as a cementing operation is performed even when tools that perform the cementing operation generate acoustic noise that interfere with measurements used to evaluate cement bonding quality. These methods may include transmitting acoustic signals, receiving acoustic signals, filtering the received acoustic signals, identifying magnitude and attenuation values to associate with the received acoustic signals, and comparing trends in the magnitudes with the identified attenuation values. These methods may also include correcting attenuation values associated with measured data based on a set of correction rules such that bond indexes can be identified. Such correction rules may be associated with data generated by a computer model.