Acoustic Waveform Stacking for Noise Reduction in Logging
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Solution Overview
Problem
Acoustic logging while drilling in subterranean formations faces challenges with noise interference, leading to poor signal-to-noise ratios, which affects the accuracy of compressional and shear wave velocity measurements.
Innovation Solution
The method involves grouping received acoustic waveforms based on measured borehole conditions such as standoff distance and azimuth angles, followed by waveform stacking to produce averaged waveforms, which are then processed using a semblance algorithm to improve signal-to-noise ratios and enhance the reliability of calculated slownesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic logging measurements are performed in noisy downhole environments, then measurement data can be obtained, but the signal-to-noise ratio deteriorates due to various noise sources
Solution Approach 1:
The patent segments the acoustic logging data by dividing waveforms into different groups based on borehole conditions such as standoff distance and azimuth angle. This segmentation allows for selective processing of specific waveform groups that meet predetermined criteria, thereby improving the signal-to-noise ratio by excluding noisy segments from the final measurement.
2Measurement precision
If waveform stacking is performed to reduce noise, then measurement accuracy improves, but processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-sorting waveforms into groups based on borehole conditions before performing stacking operations. By establishing predetermined criteria for waveform inclusion in advance and organizing data beforehand, the processing complexity is reduced while still achieving noise reduction and improved measurement accuracy through stacking.
Data Source
AI summary
A method for making acoustic logging measurements includes grouping received acoustic waveforms into one of a plurality of groups, each group being representative of a measured borehole condition (e.g., a range of measured standoff values and/or a range of measured azimuth angles). The waveforms stored in at least one of the groups are stacked so as to obtain an averaged waveform. The averaged waveform may be further processed, for example, via a semblance algorithm to obtain at least one acoustic wave slowness.