Local FK Transform for DAS Signal Noise Suppression
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Solution Overview
Problem
The existing methods for improving the signal-to-noise ratio of DAS data in seismic exploration are inadequate, as they either fail to completely eliminate noise or risk harming effective signals, and there is a lack of fidelity processing methods using local FK transform.
Innovation Solution
A method and apparatus that utilize local FK transform to suppress random noise in DAS data, adaptively removing partial FK spectral components based on scanning energy under different apparent slowness, thereby improving the signal-to-noise ratio without reducing fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency wavenumber domain filtering or median filtering is used to improve signal-to-noise ratio, then noise suppression is achieved, but effective signals may be harmed and noise cannot be completely eliminated
Solution Approach 1:
The patent divides the seismic data processing into local segments using sliding windows, applying FK transform independently to each segment. This segmentation allows adaptive noise suppression while preserving local signal characteristics, resolving the contradiction between noise reduction and signal fidelity.
Solution Approach 2:
The patent applies different processing strategies to different local regions of the data based on their specific characteristics. By making the filtering adaptive to local conditions rather than uniform across the entire dataset, it achieves better noise suppression while maintaining signal integrity in each local region.
2Measurement precision
If conventional filtering methods are applied to DAS data, then some noise reduction is achieved, but the processing complexity increases and complete noise elimination is not realized
Solution Approach 1:
The patent extracts and removes specific FK spectral components that correspond to noise in the frequency-wavenumber domain, while preserving the signal components. This selective extraction approach achieves effective noise reduction with controlled processing complexity.
Solution Approach 2:
The patent transforms the data from the time-space domain to the frequency-wavenumber domain using FK transform, changing the parameter representation to make noise separation more effective. This parameter transformation enables more efficient noise suppression compared to conventional filtering methods.
3Ease of operation
If optical fiber is laid in suspended mode in the well, then installation is simplified, but coupling with well wall is poor and signal-to-noise ratio is low
Solution Approach 1:
The patent uses FK transform as an intermediary processing step that bridges the gap between the suspended fiber configuration and the desired signal quality. By transforming to the frequency-wavenumber domain and selectively filtering, it compensates for the poor coupling conditions while maintaining the installation simplicity of suspended mode.
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
The method effectively suppresses noise in borehole seismic data collected by optical fiber DAS, significantly improving data quality and ensuring the integrity of seismic data for subsequent processing and interpretation.
Implementation Method 1
obtaining an intermediate signal through FK transform
Implementation Method 2
performing two-dimensional FFT inverse transform on the intermediate signal with the partial FK spectral components removed
Data Source
AI summary
A method for improving DAS signal-to-noise ratio by means of local FK transform. The method includes: acquiring seismic wavefield data; segmenting the seismic wavefield data into a plurality of pieces of local data, wherein each piece of local data has the same dimension as the seismic wavefield data; processing each piece of local data by means of the following steps: performing FK transform to obtain an intermediate signal, removing some FK spectrum components from the intermediate signal according to scanning energy which corresponds to the intermediate signal under different apparent slowness, and performing two-dimensional inverse FFT on the intermediate signal, from which some FK spectrum components are removed; and combining all the processed local data, so as to obtain new seismic wavefield data.