Strain-Field Surface Wave Dispersion Extraction for DAS Data
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Solution Overview
Problem
There is a lack of theoretical methods for accurately extracting surface wave dispersion curves from Distributed Acoustic Sensing (DAS) data, which are based on seismic strain or strain rate fields, limiting the application of DAS technology in surface wave dispersion imaging.
Innovation Solution
A method is provided for extracting surface wave dispersion curves using strain fields, involving data extraction, pre-processing, Fourier Transform, Frequency-Bessel Transform, and picking dispersion curves, tailored for single-component or multi-component DAS data with different source types, including active and passive sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional seismic observation methods are used, then surface wave dispersion curves can be extracted, but the observation cost is high and the application range is limited
Solution Approach 1:
The patent replaces traditional mechanical seismic observation instruments with Distributed Acoustic Sensing (DAS) technology that uses optical fibers to detect seismic strain fields. This substitution enables high-precision surface wave dispersion curve extraction while reducing observation system complexity and cost, as DAS uses existing optical fiber infrastructure rather than requiring complex seismic sensor arrays
Solution Approach 2:
The patent demonstrates that DAS technology can extract surface wave dispersion curves from various types of seismic observation data including active source data with known/unknown sources and passive source data. This multi-functionality allows a single observation system to serve multiple purposes: imaging shallow surface structures, detecting underground media properties, and analyzing seismic wave propagation characteristics
2Adaptability or versatility
If DAS technology is used to observe strain fields, then observation cost is reduced and application range is widened, but there is no clear theoretical understanding for accurately extracting surface wave dispersion curves
Solution Approach 1:
The patent introduces strain field theory as an intermediary between DAS observations and surface wave dispersion curve extraction. By establishing the theoretical relationship between measured strain components and surface wave propagation characteristics, the patent enables accurate dispersion curve extraction from DAS data, bridging the gap between the versatility of DAS technology and the precision required for seismic imaging
Solution Approach 2:
The patent transforms the analysis from the time-domain to the frequency-domain by applying Fourier transforms to the strain field data. This parameter change enables the extraction of dispersion characteristics by converting temporal-spatial information into frequency-spatial representations, making it possible to identify surface wave modes and their corresponding dispersion curves from DAS measurements
3Measurement precision
If Frequency-Bessel transformation method is used, then multi-mode surface wave dispersion curves can be extracted from array seismic data, but there is no theoretical method for extracting from single-component or multi-component DAS data
Solution Approach 1:
The patent segments the strain field data into different components (vertical normal strain, radial normal strain, tangential normal strain, radial shear strain) corresponding to different surface wave modes. By processing each component separately through the Frequency-Bessel transformation, the method can extract specific multi-mode dispersion curves (Rayleigh waves, Love waves) from DAS observations, making the complex extraction process manageable and theoretically sound
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 fills the gap in extracting surface wave dispersion information from DAS data, providing a powerful tool for imaging underground structures and offering practical value for Rayleigh and Love waves dispersion extraction.
Implementation Method 1
Transforming the strain components from Temporal-Spatial Domain to Spatial-Frequency Domain by Fourier Transform
Implementation Method 2
Transforming the strain components from the Spatial-Frequency Domain to Frequency-Phase Velocity Domain by Frequency-Bessel Transform to obtain a surface wave dispersion spectrum of the strain components
Data Source
AI summary
A method for extracting surface wave dispersion curves based on strain fields is provided. The method includes: extracting strain data from seismic observation data; pre-processing the strain data according to types of the seismic observation data to obtain strain components; transforming the strain components from Temporal-Spatial Domain to Spatial-Frequency Domain by Fourier Transform; transforming the strain components from the Spatial-Frequency Domain to Frequency-Phase Velocity Domain by Frequency-Bessel Transform to obtain a surface wave dispersion spectrum of the strain components; picking surface wave dispersion curves according to the surface wave dispersion spectrum. The embodiments fill the gap in extracting surface wave dispersion information from DAS data, and provide a powerful tool for extracting surface wave dispersion information suitable for single-component or multi-component DAS data, which has important theoretical significance and practical value for the development of surface wave dispersion imaging methods based on DAS observations.